Microinverters Vs. String Inverter - Which one is better? | Solar System 

You are the first professional that I’ve encountered, that has dared to say DC optimizers are better then micro-inverters. And I could not agree with you more. If you go with a hybrid inverter like SolArk 15k or EG4 18k, you can add more batteries yourself (plug and play) for battery storage and you are not losing 10% of power going from DC-AC-DC-AC like you would if you have micro-inverters and battery storages because batteries take DC power. I’m a fan of Tigo optimizers which are rated for 700 watts, so no clipping. For my all electric home with minimal roof space, I’m going with DC optimizers and a hybrid inverter for the best bang for you buck and like you said, easy of adding panels or batteries later down the road. Thanks for sticking you neck out and making such an informal video knowing you are going to be chastised. Totally respect your bravery to go against the grain and to be open to criticism. Shows that you care about your customers

It's good to hear you (someone) talk about the long term considerations. My top concerns are how solar will last and what problems we, or my wife if I'm gone before her, will have to deal with in the future. So thank you for raising these things.

Thanks for being honest, transparent and putting customers 1st and not what other people think.

Probably the best microinverter video online. You've clearly been doing this for a long time and found lots of problems. Fantastic. Subscribed.

As a maintenance engineer, i entirely agree. A 25 year warranty on electronics in a rooftop environment is optimistic, and ultimately commercially meaningless if the company changes name every 5 or 10 years to duck their obligations.

My wife is going to start asking questions as to why I keep having coffee with Martyna. I appreciate the explanation and the recommendation. We should all 100% take this as fact, as you are a professional solar installer and deal with this every day, for years now. I am in IT Security and if someone asked me to setup a security posture for their home/business, I would hope they would take my recommendation as well, as I do this every day. I am not a professional solar installer, so when SolarTime recommended string inverters rather than micro inverters, I said yes please. One of the reasons I felt I didn't need to come back with my opinion or an extra explanation from them is they already showed me they weren't in it for the money, but in it for the quality and service to back up their warranty. If it's easier to service, easier to maintain, when things go wrong...I'm all for it. Keep fighting the good fight, you have an great argument!

Lot’s of good points. I have a 13 year old 4K, roof mounted Enphase system. I do have some shading issues and sometimes snow shading. I have been very happy with that advantage of micros. And I do like the rapid shutdown feature built into micros. When my system was installed, Enphase was selling the 2nd generation, D-380 micro. It was a short lived, 2 panel input, with 2 internal 190 watt micro in one box. They had a 15 year warranty. At that time everyone got per panel monitoring software free. So over the 12 yerars, I was able to see all but one D-380 micro fail. Enphase was great at sending out replacements with required cable adapters, and I am was able to replace the failed inverters myself. At the last failed D-380, they even set a replacement for the last still working D-380, which I thought was pretty good service. The latest replacements, look like the M-7 case, but have software that is compatible with my older “Envoy” monitor device. So all and all, I’ve had very little downtime, but my constant monitoring of my system, caught the failure’s right away. I can’t help but wonder how many systems have failed micros, that no one is noticing, especially since per panel monitoring became an option for the end user later on. Today, if I were to do it again and had the money and space, I would definitely go with a ground mount, hopefully in a place where shading would be limited, and a hybrid inverter like SolArk. With a hybrid, and even a small battery, you can use the power from the solar panels when grid down, which isn’t happening with micros like I have. Just my thoughts, and 13 years of experience.

Great video and review on the type of DC converter units and types. I have IQ8+ on my system and have had 2 fail and one replacement by my installer which filled bankruptcy "Solar is Freedom " and left their customers out in the cold!! I dealt with Enphase directly on the second unit and replaced it myself and Enphase did exactly what they said over the warranty and just plug and play and they did the reset through the app and working perfectly again 😊

Great advice. I recently installed a Solar PV system with a hybrid string inverter. Yes it is a single point of failure, but if it fails it is a simple job to replace it. Keep up the good work. I am really impressed with your risk analysis. I wish you and your dad continued success with your business. I love your honesty delivered so clearly with such integrity.

On string inverter system, it is also VERY usefull to have a ARC fault detection that isolate the load. THIS is what avoid fires due to numberous serie HV connections that each can fail. Breakers fail, fuse fail, MC4 fail, and bad connection from unthightened screw , all can lead to fire on HV. Where Micro Inverter DONT have any problem with that safety issue as these are all below 50V DC and the AC side is crossing zero every 8 milisecond to extinguish the arc. If a micro inverter fail.. it will very rarely cause fire, It just stop working. however, if a serie connection fail on one panel of a string setup during load without any ARC fault detection, it can become way more complicated and dangerous.

Fantastic video, this is one of the few "large picture" forward thinking conversations that isn't just a sales pitch. 😍 I appreciate your honesty and transparency. There are some excellent long-term concepts for homeowners to consider prior to investing in solar. ☀

Fantastic video! All of the points you speak to are the reasons I went with string inverters on my 14.2 kW system just installed 6 weeks ago. The SMA Sunny Boy inverters with Shade Fix provide an excellent solution to shading.

As a homeowner who opted for the LG branded solar panels with their microinverters in 2017. And found they have walked away from the business i can see your point! So far only 3 failed panels which were replaced a few years ago.... Time will tell!

About 6 years ago now, I was part of a "Solarize" campaign in the town. We found an installer, signed people up, and based on the total installed wattage got everyone discounts on the install. Part of my involvement was the technical side. I was solidly in the SolarEdge optimizer/string inverter camp. Another person on the board was sold on the microinverter. We both had our systems before the "solarize" program started, so none of the opinions mattered to us overall. Just so happened the installer offered both solutions. People chose which one based on which of us they liked it seemed. And then 85 homes were installed over about a year. The other guy had a microinverter on his system fail. What did he care, it was under warranty. All fixed. About 5% of the microinverter systems have had warranty work now. NOT ONE of the SolarEdge systems I know of has had any component failure. We did have one installer failure where a junction box wasn't properly set to drain and it corroded the cables inside. None of the inverter or optimizers failed. Just a couple cables due to the standing water in the junction box. My inverter is fed a steady voltage maintained by the optimizers. It's very efficient and lives in a climate controlled basement. The other thing I like by having DC to the basement is that if I want to add a battery pack, I'm not converting from DC to AC and then back to DC in the battery and then back to AC yet again to use it. DC charges the battery and I only get the AC loss when the power is converted. DC to DC conversion is FAR more efficient. In my mind, it's not only simpler, but single point of failure is in a very controlled environment and my options to expand later are FAR better served. Good on you for thinking about what happens down the road. People I sat with who heard my arguments understood the case I was making. Those that sat with the other guy never heard them. My understanding is that the microinverter solutions were also generally more expensive overall by a little bit. The only time a SolarEdge install cost more was when there were a lot of different roof facings and thus many more strings to manage.

Very enlightening ! Thankyou. Longevity was one subject that I had not considered because I took for granted that a 25 year warrantee would be valid for that length of time. The reality is only maybe! Yes you have changed my mind!

I thought this was super helpful. I’m still so early in the process, like a year or more before I’m ready to install solar, and I’m still trying to sort through all the options and variants, that I don’t know the trade offs at all. Thank you for this! Most helpful.

Interesting viewpoint! I designed and built my own 7.8kw system and decided on a SMA string inverter with Tigo optimizers. The biggest reason is because it was less expensive but it still gave me many of the benefits of microinverters. I also like not being so reliant on one manufacturer. With Tigo, even if one fails and I can't replace it, I can just remove it and it will still operate but without the monitoring and optimization. Also I have designed electronics that will work at 350 degrees F. It just depends on how much money you want to spend on higher quality parts and additional testing. The quality vs. cost tradeoffs are always a battle.

I'm old enough to remember when folks were hooking their panels up to forklift batteries and using 12v to run their cabin. This discussion is quite valuable. Thank you for getting brave.

That was a very good presentation. After reading the comments your viewer brought up some other concerns about battery storage as part of the system and the conversion losses. Thanks for putting out you view and thoughts.

Looking into solar now. We physically built our house, not subbed out or paid a general contractor. We made it handicap accessible for our future. Would like to do my own install. Just retired now and have done many different types of construction. The sales person started off with micro inverters are the way togo. Thank you for your time and assistance. I will be watching your other videos. Thank you Martin

Thank you for this great video! As someone who spends a lot of time in Europe, I've never understood where the hype for microinverters in the US comes from and why it is different than anywhere else in the world! String is much cheaper & hussle free for maintenance. I have a system with bypass diodes and a SMA Sunny Boy inverter (that has Shade Fix). It's perfect!

Excellent, thought-provoking presentation! Here's my question - What's the Mean Time To Failure (MTTF) of a high-quality micro-inverter compared to a bypass diode? In other words, what is the statistical probability that a system with high-quality micro-inverters will fail within the 25 year warranty period compared to the probability that a system with a high-quality, properly sized string inverter will fail? If both kinds of solar arrays are very likely to last 25 years without failure, then the entire system will probably have paid for itself by then, and after 25 years there's a good chance that new, more efficient technology will make it cost-effective to replace the whole system.

I think all systems need to be looked at under different circumstances. There are some areas and specific systems that micro inverters work better. There are also many systems that a string system is better. The problem I have seen in the solar industry is solar companies that get fixated on one type of system, or one brand of components used. To really be a consumer advocate, different products for different situations or customer preferences should be explored. Some solar companies don't push a different type or brand because they simply learned with that one type/brand and they don't know anything about other options. This makes them limited in my opinion. That's one thing I really admire about Solartime. You really can be assured that RIGHT type of system is being offered to the customer because they know about all types and brands of systems and can install many different types. I totally understand Martyna's preference on string systems because I share those preferences on most systems. (But of course, not ALL systems)

This was an outstandingly interesting talk - with only a little repetition. Congratulations and thank you Martyna. You have made me pause from implementing what I THOUGHT was going to be my solution - but it leaves me stuck for an alternative! I'm trying to work out a solution for a complicated small array that will have at least 3 strings (two - with different orientations - of thin film CdTe solar glass with 87Vmpp 116Voc & 0.78Aoc) and one of ~5 conventional roof-mounted panels. All strings subject to intermittent shade and with up to 25m cable run to battery/inverter. BUT: No hybrid inverters are available in UK with more than 2 channel MPPT tracking (no Powerwall 2+ here) so.......... ......I'd therefore been thinking about a microinverter system and arranging the solar glass modules into groups of 3 parallel or 4 in two series-parallel pairs to match the microinverter inputs. When I look at DC optimisers I see the same multiple points of potential failure as with microinverters and same potential future backwards-compatibility problems that you point to. I also see concerns about Tigo optimisers from an authoritative source (www.mcelectrical.com.au/tigo-optimiser-recall/) and that SolarEdge is excluded by our installation's short strings. What I really need - I am beginning to think - is a 6-MPPT Powerwall3 - but that's just vapour at the moment, and it may - like their glass tiles - never come over the horizon, trumpets sounding. So maybe what I will HAVE to make do with is two small hybrid inverters, though I don't yet know if their outputs and interaction with a single battery can be successfully managed in a domestic setting. See! I AM coming round to your way of thinking. What do you make of this slightly unusual dilemma?

I'm with you Martyna. I think a big iron central inverter is the way to go. Get a good brand name inverter, keep it in the shade and out of the weather, and it should last 10+ years. If / when it fails, an installer can swap in a new inverter in no time.

As an engineer who did some electrical engineering at University, I wholeheartedly agree with your views. I just came across your videos today: micro vs optimiser video. Love your work. I am now hooked.

Im an installer in Puerto Rico and I am 100% with you . Great info

You can not add panels to a string. You will need one that has the same Impp in order to work. There is a lot of FUD in your video. If you install optimizers and one fails, you also have to go on the roof and hopefully have the right map available. It has the same points of failures as with microinverters +1 (the central inverter). Comparing what happens when you put a phone (made to be used not in rain or full sun) out in the sun with a device that is designed for being out under a panel (so not in direct sun) is kind of useless. If you have shading issues, I think AC coupling micro inverters with a hybrid string inverters is an excellent solution and ready for the future.

I totally agree with you on string inverters. All inverters fail sooner or later and working at ground level is much simpler. I've had a string inverter system for 24 years. It was upgraded 8 years ago and I'm currently working to replace the SMA inverter with a Powerwall 3. The current inverter is maxed out so I hope to be able to add panels with the Powerwall.

What if Optimizers fail? You have to go up and replace it too. What I know is that Optimizers fails more often than Microinverters.

Good to hear information that I have believed for years. Electronics that are subject to extreme heat will always fail over a period of time.. Way before the whole PV system needs to be replaced.

I watched the video 3x. Wow, it's got me thinking now. Gr8 vid.

Great points on micro-inverters. I never thought about having to replace all micro-inverters because of compatibility on older failed models.Thank you. I installed a sol-ark string inverter and panels on my home. What annoys me is the NEC code requires panel level shutdown. So I still have Tigo units on each panel for the rapid shutdown stealing power from my system. I think the panel manufacturers are adding more circuits to the panels to combat the shading issues.

The single point of failure vs. multiple points decision is easy to decide. If you are in a plane flying across the ocean, and you have an engine failure, isnt it better to have four engines with one failing? You can still fly home on three engines. With a single large engine, when it fails, so do you. If one microinverter fails, I still have >90% of my power generation, and I can take my time replacing the failed unit. Yes, it is more difficult to replace a unit on the roof, but it is also not a major project. Finally, I would agree that if your plans are to expand your system in the future, it might be better to go the string inverter route.

Hm, I somehow fail to see how "supplier going out of business" applies only to microinverters. The same could happen to . Then what? The immediate consequences for the customer are even worse if your string inverter dies (no production at all vs. the few % loss that the single microinverter was contributing). Now, probably you'll see more microinverters die than string inverters, simply because there are more of them per installation. As a business, you'll have that factored into your pricing. I could imagine that instead of ripping out all microinverters for affected customers, it would have been cheaper just to compensate them for the loss in power production over the span of your warranty. Post warranty, this would even turn into revenue service calls. There are good technical reasons for micro- or string inverters, depending on the specific installation. That's why an engineer designs a solar system. Making a supplier that bailed on you the only decision criterion seems more knee-jerk than engineering.

You are absolutely correct. Have an Enpahse Microinverter system and tried to get an expansion by 4 more panels. The Installer never came around to do it. Now I understand. There are probably no compatible micro inverters available anymore.

Which would you go with? Estimated $3k difference going from Tesla String inverters (2) to a single SolarEdge with optimizers. Pretty decent sun exposure in ATX but some trees on the perimeter panels in the morning and evening. I'm leaning toward just string inverter but also like the panel level monitoring of the optimizer system.

Totally agree. Especially for the future and durability. A basic string has less electronics and connectors so less can break. Also adding a battery is more efficient ( dc to dc ). Great video.

I like the way you explained bypass diodes - very clear 🙂

my degree is in IMET specializing in solar/wind (hate wind). i have done a few installs. one, the only one that was a failure is where the customer went with what the salesman told her and not with the math i showed her from a storage/use/available hours and such. her salesman told her 400W would be enough to run 800 watt reefer and an icemachine and fan. you can do the math on the reefer and know she did not have the charge power during sun to run the thing, never mind that night. all my installs have been to industry (commerical) standard, soldiering points where that is the standard, and torque standard on panels and such. the point is i'm a professional as you are. the trackers only add 25% more power and ROI usually is not worth it. you are correct on the fail points. industry standard is to have as few as possible, and to have check points to isolate specific areas just for the points you state that you may have to pull 30 panels to find one bad inverter. you are doing it right. as for the install i spoke of, she later called the school i was in, and talked to the dean and asked if what i had stated was correct and he said yes, the salesman had not sold her the correct system as she did not have the power required for an uncooled home with a reefer pulling 800 watts an hour. she continued to bad mouth me for a long time which actually was a good thing as people would call and i was able to educate them to get the right system. good video i like you a lot for being such a strait forward honest person

Great video. Thanks! I'm researching for a new system and my number one concern with microinverters is the potential EMI from all those switching supplies. As a corollary, I have concerns with such power supplies in the presence of radio transmitters (example a solar backup option at a mountain top communication site); Intermodulation is a real thing with switching power supplies and I have to ask what steps have the micro inverter designers taken to ensure compatibility with the electrical surroundings. The same might be true for power optimizers though.

Thanks for the perspective. I've yet to make the choice which way to go.

Thank you for the information. Lots has changed in 4 years. I have an Enphase system. I watch a few of your test videos. I am amazed how well string inverters performed. Keep up the good work. You don’t talk over my head. You have embraced the k.i.s.s method( keep it simple silly).

Some thoughts to add since people may just not know. Where is the main "brain" or ECU on your car? You'd probably be surprised. Imagine trying to drive a Model T today, most people wouldn't. Just because "string was first" isn't a good enough reason for me. If that's how you feel, please think about it a little. We certainly don't have many still using "dinosaur" phones now. Even the basic flip phones are semi-smart and android. Technology has moved along so well, we actually brought the compact style of flip phones back. What happens if the company who makes the "optimizers" goes under? Do you lose panel-level tracking and hope it stays working? It's the same issue as any other company going under. Curious to know about that customer that wanted a few more KW, were you not a dealer for that brand? Enphase will still sell new looking IQ series inverters, that can talk to EITHER old Envoy-R OR new IQ systems... 1. The Kaco "rebranding" or "strategic removal" of themselves from the US market can happen with literally ANY large company. Look at LG for cell phones recently. Imagine they did that for their solar. SMA, MPP-Solar (Voltronic like the EG4 brand at times), none of the smaller brands are actually a "safe" bet. Any company can do this at any time, in any market. Happens all the time. 2. Enphase micros will actually produce power without a controller (I have the older M190 and M215 series and the IQ still do this to this day AFAIK), you just wouldn't get monitoring. If you add even a used Envoy controller, you can get system output without true-panel level monitoring, at worst. They all have a self-hosted site you can visit for information about the micros and power outputs. Enphase compatibility is pretty good. Envoy-R for M series micros, IQ Envoy for anything newer (IQ6,7,8 series). You can have two envoys running two different generations at one location. 3. You wouldn't need to "remove the whole system", you could have started an in-place upgrade or change to micros if that's what the customer wanted. You could have run a 240V line, and set up one IQ Gateway (Envoy), and had just that one panel on the Envoy system. 4. To those who haven't seen inside, the "electronics" inside micros or "optimizers" are usually potted, so completely sealed from weather and have great heat characteristics. If you don't want any electronics on your roof, don't get optimizers either. How do you think they shutdown the panel? It's a SSR or relay. 5. How many old cars are on the road? Think about the harsh environments the electronics on them go through. Dodge, along with Jeep, and even Audi, like to keep their ECU's UNDER THE HOOD, in the heat of the engine bay. Shaken around all day, anytime you're driving. Starting the car? Relays under the hot hood usually, pulling 50+/- Amps to crank it over. Most cars work 25+ years before having any serious electrical issues. They all have tens of feet of wire that "wiggles" all the time, over any bump (on a very very small scale). I'd expect well designed micros to be the same. If you live in an area with crazy shading like I do, you'll want micros. I've had multiple string inverters, and they work, but I get much more usable power from my enphase system than I ever do on my strings. They're both really good options, but let's not make it seem like one is worse than the other. IMO with the new rules for rapid shutdown, strings will be more complicated and have higher DC on their lines. An "optimizer" is just a dumber micro. It's all of the micro parts except the inverter, so we're already putting basically the same thing under the panels in the heat and weather. They're still doing line-level communications, and rapid shutdowns, just no inverting. We've gotten very good at breakers detecting AC voltage issues outdoors, we do it all the time in many situations (pool pumps, heaters, outdoor lights, outlets, etc). I have only old decommissioned enphase equipment and it's all been rock-solid. I've also heard nothing but good things of their warranty. I still have my strings, but with any big shading or clouds, enphase is always ahead in output, driving down the most important thing, my time to ROI.

I own a cheap Growatt and it works more than fine its a 1200 dollar Hybrid and happy with the string inverter .Regards from Holland

Point 1 - I don't think Enphase is going anywhere. They have a huge segment of the market and are profitable. And you could apply this logic to optimizers as well. If SolarEdge went out of business, I don't think you'd want your SolarEdge optimizers attached to another brand's inverter. Point 2 - Micro Inverters are not phones, they're rated for use at up to 140 degrees, again, you can say the same thing about optimizers, but those too are built to remain outside. Failure rates are incredibly low. Point 3 - This would depend on if each string has reached capacity. That capacity is based on which micro inverter was used. The combiner boxes that they attach to allow up to 4 generations of micro inverters from what I'm reading. Worst case scenario, you'd run a new string to a new combiner box, which is about $700. Enphase will still sell you the Enphase IQ7 generation which is ~5 years old now. Point 5 - I think customers would rather have more redundancy by losing just a single panel of production, rather than losing a central DC inverter, putting their entire system out of service until it's replaced

Nice Video Martyna, Just notice i took the risk and went with microinverters since my house the only way was installing those box in the front of the house and did not like the look on the other house I see since they only had 1 String Inverters and my configuration needed 2 Inverters. So i took the risk as anything in life. Hopefully i get a lot of years out of the 8 Microinverters on my roof. Live in Panama. 2025 will try to go with the battery when I get some financially breading room for that investment

I'm from the UK. On my roof fitted in 2012, is a standard 9 string panels wired up in a snail configuration so I have both plugs coming back under the tiles in the same place. Keeping the wiring to the minimum. And on my solar carport, I had built last year I tried the solar optimization units. I can get to these units easy, as the solar panels are the roofing material and if cat's decided to sleep on a panel it won't effect the rest! LoL. All items are good and like you say, you don't want to much sensitive products on a roof to replace if fails.

I had already come to the same conclusion myself. It makes no sense to me to have the most likely to fail devices up where I have a much higher risk of damaging my roof or being injured trying to replace it. Instead I invested in redundant hybrid inverters, will be less likely to be completely down if I do have a failure, that isn't also down when the grid is down. I completely agree with your conclusion.

Good day Martyna. This is my first time watching 1 of your videos & I'm very impressed. In South Africa we have power failures daily - sometimes multiple times throughout the day. Our appliances & smart home devices have & continue to suffer greatly. We've finally decided to get Solar but the info available out there is really overwhelming with so many opinions that takes you from pillar to post. It's not easy to swim against the current, but all i can say is keep on being bold & courageous & may God be the centre of your business always. Keep making challenging & thought provoking videos! kind regards Ian

Martyna thanks for making this video; it was a game changer. Sadly it also sent me back to the drawing board. Sure wished you worked in Virginia instead of Texas (although I have lots of family in Texas, so I forgive you :) ) Two years ago I started looking into solar for our new “forever house” and as you said everything I read or saw on RU-vid pointed me to microinverters. While I loved the integrated system that Enphase offers, I hated the DC to AC to DC to AC inefficiency. Eventually, I discovered Solar Edge's string inverters, but backed away from them when I learned about their maintenance reputation. Your video introduced me to other string inverter options. I’m looking for a 8Kw PV system with two inverters and probably 10K battery backup. You correctly pointed out that micro inverters have 20 or 30 points of failure, on the other hand, the Army taught me to limit single points of failure. Failure = 2 is 1 and 1 is none; so a single inverter doesn’t work for me. Any recommendations?

I think your logic of string vs micro inverters is wrong. If someone has either and the company that makes either goes out of business it’s going to cost you $9k plus to replace the bunch. You will still need to lift each solar panel and replace either optimizer or micro inverter. As far as the consumer, and I’m talking from experience, if I have the optimizer system with a single large inverter then I have a single point of failure problem. And the single point of failure is the large inverter. When that single inverter goes bad I’m back to paying $600 to $900 per month electric bill until the inverter is replaced. And my experience is expect to wait 3 to 4 months to get the inverter replaced. With micro inverters if one goes bad the system keeps operating but not at full capacity. So with optimumizers I’m out thousands of dollars if the single large inverter goes bad and with micro inverters I hardly would notice it.

I truly appreciate your commitment to string inverters and I had a very difficult time getting a contractor to install my panels with optimizers and 1 string inverter. I would like to add storage in the future and feel that I would get more efficiency charging batteries with dc than the ac/dc dc/ac conversion.

Thank you for speaking the truth. Too many people today seem to go with what they are told and don't really think about it. I have always liked the concept of micro-inverters but wondered about the reliability in an outdoor environment and the heat cycling they go through. Also, I wondered about the energy loss when they are used in a battery storage system going from DC to AC and then back to DC at the battery, then back to AC again. I'm wanting to build an off-grid system with grid charging as a supplement/backup. I want to slowly transition my house over to off-grid where the battery bank is kept at some minimum SOC by a charger off the grid and anything over that mark is supplied by solar. As I expand my solar array I will depend less and less on the grid. I also want a system that can be totally managed locally with no internet access required. Internet access should be an option, not a requirement. Thank you for your videos. I wish you great success in business.

I think your absolutely rite about string inverters. My only hope is that they increase the warranty period for them so that they can be more competitive with micro inverters. And you are absolutely rite, if the company that installed the system in the first place is not in business anymore, it will be very difficult to get the micro inverters replaced with someone else. I'll love to hear you talk more about warranties in future videos. GOD bless you. 🥰

Martyna, I believe you are right on the mark recommending string inverters over micro-inverters, and for all the reasons you have expressed. I've been using a string inverter for over 7 years with no issues. My system is broken into 4 separate strings of 2500 watt arrays, making a 10KwH system. If I lose a panel within one of the strings, I still have 75 percent left generating while awaiting repairs. Best of both worlds! One more thing: In my experience, over-sizing the string inverter -just a little- guarantees the longest life of the entire system. I find that a lot of folks who under-rate their string inverter (to their panels) causes clipping and excessive heat at the inverter. Bad idea in my opinion. Thank you for your continued valuable advice!

Electrical Engineer here ... Micro-inverters use electrolytic capacitors and these are particularly sensitive to heat, so there is NO WAY they will survive 25 years in the constant heat of summer, spring and autumn.

As you appear to realize, your opinions are the small minority view. I have a two year old Enphase micro inverter system that has performed well, with one glitch that was quickly resolved by the installer quickly after I reported it. I have been researching the issues again because I am thinking about expanding my system because of the disaster visited upon the state of Texas by governor Abbott and the Texas legislature with “retail electric competition” which appears to be increasing Texas electricity rates by about a third! So I am going to increase my solar production by about a half with more Enphase equipment including micro inverters and maybe more battery capacity. No way I would consider string inverters, which also need optimizers on the rooftop under each solar panel, which apparently are less reliable than my rooftop inverters. Thanks for your advice, but I’m totally convinced that you are wrong.

Thank you Martyna for the educational and honest video. I am just a customer looking for going solar in my house. I have 5 (very costly) quotes, all with the microinverters. I am looking for alternatives, so if you provide design systems in Virginia, please let me know.

Hi, a question about the micro inverter story you have at 8:30 ... if a company goes bankrupt... even a micro inverter company... I've talked to installers on this point on this very topic... you can use any other micro to continue producing AC to the home (and also you have only lost 1 or 2 out of 20-30 micros which is insignificant)... that's the benefit... the decentralized nature of the system. Yes app level detail may be gone if the company is bankrupt but the micros still work and produce energy since its AC energy... and they don't stop because they can't communicate... that's not how they work. And imo - you don't need to replace them all if only 1 or 2 failed. Unlike if for example - if a power optimizer goes bad from Solaredge or if they go Bankrupt (doubtful i admit) then we are left with a system that won't function since that's where they all talk together to the main inverter... the power optimizers need one working system... not the micros. Would like to know what you think on this. thanks for the video.

This video is useful and made me think differently, thanks for the effort and it's always nice to see a different point of view.

Congrats on a well balanced explanation of your view on string vs. Micro-Inverters, the long term lifetime of a solar panel system for the customers and the installers. I agree with you. Better to focus on modularity vs. compatibility.

From a solar company perspective, all of your salient points are spot on. However, from a customer perspective, I don't agree. I'd rather have 32 potential problems on the roof that will only knock out 1 32nd of our system's power, rather than a single source of failure. Yes, you don't need to up on the roof to replace a string converter, but I've seen a lot of systems that were down for long periods because the solar company was initially paid and just doesn't care anymore. That's the biggest problem with the solar industry right now...

Very educative , I use a string inverter Growatt in lagos Nigeria & had been thinking of either getting optimisers or micro inverters but some of your concerns have occurred to me as i mostly do the installation DIY . Thank you

Great video and I am convinced when I am ready and I will definitely call you for my project which will be all home solar. And request strings

Thank you for this video and sharing your extensive experience. Micro v string has been my dilemma for 6 months on a simple E/W arrangement with no shading whatsoever. I concluded that spending more money on REC Pure R panels was the better choice and letting them do their thing whilst coupled to a simple Growatt 2 MPPT string inverter at ground level is the best solution. K.I.S.S still applies.

Hi Ma'am you sound very responsible Business Executive in this era. 🙂 This is brilliant presentation. Thanks for giving and insight to Micro-Inverter vs DC Optimizers

Good presentation with several point worth considering. As a licensed engineer it should be noted for Enphase, the IQ7 & IQ8 are NEMA Type 6 Enclosures constructed for either indoor or outdoor use to provide a degree of protection to personnel against access to hazardous parts; to provide a degree of protection of the equipment inside the enclosure against ingress of solid foreign objects (falling dirt); to provide a degree of protection with respect to harmful effects on the equipment due to the ingress of water (hose directed water and the entry of water during occasional temporary submersion at a limited depth); and that will be undamaged by the external formation of ice on the enclosure. As for temperature, both are rated from -40 to 149 degrees Fahrenheit. So as long as they are installed per manufactures requirements they should operate normally. Cell phones on the other hand are rated from 32 to 109 degrees Fahrenheit so that is an apples to oranges comparison and not valid...

You hit the nail on the head! Thank you. If you want split phase AC, it is easier to convert DC to split phase AC once right?

Wow, thank you for your excellent video! It started out with a few weak arguments, that almost prevented me from seeing your main argument: who has the largest stand on a fair is no indication whatsoever of the quality of their products! I am researcher into wind energy and trust me on that one... In Europe string converters with optimizers are the standard solution today. But I was totally going with Enphase microinverters in Germany, especially because of their higher safety: sure 230 V is higher than 50 V, but it is way lower than 400-600 V and that does make a difference if something goes wrong, better efficiency and it is also rather elegant to have native 230 V AC going into my 230 V AC house... The main reason for microinverters was the 25 years warrantee: I am 63, so 25 years would likely last me a life time - always good not to have to exchange inverters when you are 80 or so! I intend to install 25 panels, plenty for a 1 person European household with A/C, and a chances are that in this 25 years 1 or 2 inverters will fail are real - but I then have the choice of exchanging these, or simply close my eyes to it and continue with 23 panels. Extreme temperatures are no problem in northern Germany, but electronics outside and exchanging inverters and getting them into the system would be. So, many thanks again for sowing doubts into what was already a foregone design choice!

This is the confirmation bias I was looking for 😄 - String inverter it is.

In conjuction with a battery ESS (Energy Storage System), the micro-inverter systems seem to be more specifically ideal in medium-to-heavily shaded areas with a ground-mounted solar array system with easy access to the back of the solar panels and micro-inverters. For most other conditions and situations, the string-inverter + power optimizer combo would be the better solution, especially long-term, as you explained very well in your video.

I'm planning a new solar installation for our home next year and considering the Mango Power M storage solution. Question: Since the Power M comes with its own hybrid inverter that will handle up to 18 kW of DC input, will I still need a separate string inverter? We plan to install 10-12kW of solar panels on both the east facing and west facing roof (5-6kW on each side). I'm hoping to use just the inverter that comes with the Power M since it also allows a generator connection and will simplify the installation process. Am I heading in the right or wrong direction with my thinking?

Hi, i 100% agree with you. My oldest PV system is 24 years old. Its build with a single inverter from SMA with two strings. Once after 14 years the inverter was broken and after a phone-call to SMA they sent a refurbished one for 300€. I only had to send back my broken inverter. That was so easy, i dont want to think, what happend, if i had to search for a defect on my roof. By the way, the Panels are from the no longer existing company SIEMENS-Solar and running for 24 years now, with an output of 90% from the beginning! Warranty was 20years in those early days of solar industry 🙂

I use string inverters because I can easily attach any amount of battery storage, and we can live off-grid if necessary. Microinverter systems shut down if the grid goes down, unless you have some additional equipment installed to handle it - and that puts the system cost up a lot, and processing AC is just more inefficient than DC.

I am now seriously planning to install a pv+battery system . (I plan to do as much diy as possible--the wife does not want me on the roof, but I told her that I will use a harness. She keeps saying it's dangerous and reminds me that I'm in my mid-60s.) For fault tolerance I have decided on three hybrid inverters (most likely the EG4 12kKpv paralleled) for our all-electric home. Each inverter will receive at least a fraction of the total PV strings.

I prefer Victron, Dc coupled, dc mppt 150, 250 or 450 vdc from the roof, transformed down to 48vdc which goes to either into a 48vdc inverter or storage batteries. Nice video btw.

Thanks for sharing your thoughts and ideas. Very interesting perspective. I’ve been watching and thinking about the various systems but found your perspective on this well thought out and thoughtful from the installation perspective. Wishing you and your family the best.

I was thinking of going the microinverters route when I go solar in a few years but you made some very excellent points about replacing a single central string inverter vs multiple points of failure in a microinverters system. Also the fact that what happens if enphase goes belly up within their 25 year warranty period whereas a string inverter is more easily replaced from a different manufacturer. Thanks to your thought provoking video I am converted to going with string inverter.

I've been studying up on solar systems and reading about solar panels, optimizers, inverters, etc. (FYI -- I have no practical working experience with any of these things. I only just started studying them.) Earlier, when I realized that optimizers and microinverters were used at the panel level (on the roof) I thought to myself, "oh oh, not good". Why? Because for electronics to survive hostile environments, especially heat, they have to be very well designed (plus, there're all those interconnections). This means parts have to be almost military grade to be reliable. It's not impossible (think electronics inside a car parked in the desert, such as the computers under the dash, or heck, even a radio). It's not impossible, but having this stuff on a roof under a solar panel in Las Vegas running everyday at 160 plus degrees? Insane. Even though optimizers or inverters at the panel level seem like a (technically) great way to go, I've been envisioning the worst possible failure scenarios. Having only just panels on the roof, with all the electronics on the ground seems like a better bet, but I think optimizers (at least) have to stay with the panel (I believe I'm right about this ... they can't be remote from the panel can they?). And if optimizers have to be there, then I guess microinverters might as well be there too. But like I said ... this stuff has to be really well designed and practically mil spec to survive that environment for any length of time. Anyway, probably the best way to go would be to have these items incorporated straight into the panels themselves (I think some panels already do this). Get away from separate components -- have the panel contain everything. Optimizers and microinverters both have transmitters now, and can be diagnosed from a computer in the house. So in the case of failure, you diagnose from the ground which panel is bad, then you go up there and replace just that single panel (with all the support electronics inside). But what about older solar designs? Got me. I guess you've just got to go up there and fix them at great time and expense.

Really appreciate your practical approach, experience and honesty. Have just come across your channel (and now subscribed) while researching a solar system for our own home. I can certainly see your logic regarding a string system. I am a little confused regarding what I was thinking of doing which is to use REC Alpha Pure RX panels and a Tesla Powerwall 3 for battery storage. With regards to the REC panels I thought that as the particular model of panel I was wanting to use has a microinverter built into them that I was stuck with a microinverter setup. So if I did want to go with the string system are these microinverters removed or bypassed at the time of installation?

The problems you point out about micro inverters is no different than string inverters both can fail and the company can Go out of business. If you have 1 string inverter and it failed your system is down until it's replaced when you have 30 micro inverters If one fails you still have 29 panels working and as far as trying to find the bad one as long as the inverters are mapped properly that's easy and one last thing yes you have 30 points of failure but the odds are very low that All will fail at the same time If you only have one string inverter only one needs to fail and you are down. You are very right about getting inverters from quality manufacturers but there is never a guarantee for any manufacturer about changing product designs at any time.

I have an enphase 36 panel system on 3 circuits which was installed 5 years ago also net metering. Knock on wood has been trouble free. I decided to have a free standing system not a roof mount. It keeps it cooler, and has a lot easier access to each panel. I would suggest only installing micro inverters on a free standing and not not on the roof. Also I installed 0000 aluminum wire on the hundred and fifty foot run to the service. What I have learned is that technology changes rapidly and by the time you buy and install the newest system it's behind what's available now. Systems have to be repairable and upgradable.

You bring up some good points but question, i was told that optimizers medels are have compatability lists and would not work with all string inverters? Also do optimizers suffer from the heat as well?

I did buy a string inverter system, with battery backup. I think you should call it "Solar talk over Coffee" or "Coffee talk Solar"😂😂😂 Love your videos and honest opinions.

so there are a number of things that made me want to go with microinverters... they have panel level monitoring of production, so if a panel or inverter were to fail, I would be able to see it immediately and be able to replace that panel or micro... if you had string inverters, you wouldn't be able to do this unless you had power optimizers at which point the cost is about the same as microinverters, but still with a central point of failure... additionally, the warranty on enphase is 25 years whereas most central inverters is 15 years if you are lucky, simply because microinverters are handling a smaller load on each one which is going to be less wear and tear compared to a central inverter (unless you oversize)... additionally, although having a single point of failure is nice for maintenance purposes, it is not great for continued production--if your central inverter goes down, you make no more power until you replace it... if a microinverter goes down, all the other microinverters are still creating power... on top of that, I have a ground mount system, so replacing a microinverter on this system would not be difficult as you can access the backside of the array... although replacing a central inverter may be easier than replacing a microinverter say on the roof, the additional cost of having a central inverter which is not even expected to last as long as the microinverters will add to the cost and make it so that the microinverter solution is often times more economical that being said, you make great points regarding replacement of string inverters, as there are more options that are more easy to replace on a system... and if enphase were to go belly up, you are correct that the 25 year warranty wouldn't mean anything

i am from malaysia ..n installing solarpanel...according to your speach ...string inverter if the instaler was very high place ...

I've had a 4.35 system installed recently with a solis hybrid inverter. One question on my mind: how would you check a string system to make sure that all panels are actually working? People say check generation, but generation can be affected by many factors like weather. How do you troubleshoot to find which panel is dead?

Thanks! Gonna stick with 10 year warranty string inverters. :)

Having separate system independent parts are what I have already decided to do. But you have nailed the coffin shut for me. Intendant units are the way to go.

micro-inverters were created before the battery revolution that has happened past couple years( Powerwall like batteries & lifepo3). Not sure it makes sense anymore to take DC from the solar panels, convert to AC, then convert again to DC to charge the local battery backup system. Power companies are paying less and less every year for individual homeowners to feed the grid with their solar power. Just get a whole home backup battery and a ford lightning to charge up, and keep all the power you generate for an emergency.

I have used Enphase microinverters for eleven years with no problems.🇬🇧

Nice to have someone realize the value of bypass diodes. Going with a simple string myself though having to bodge together RSD for parallel arc fault as there don't seem to be many options for 600Vdc AF breakers.

I'm facing this same issue now. I had my original installer upgrade my system. From 19 to 24 panels. What they didn't do was upgrade my inverter so I have serious clipping. Now that I have raised a stink about the work and design and that my string inverter wasn't upsized, I may get some relief. I agree with your point on the string vs micro battle and I'm thinking that they'll want to replace my current set up (Sunpower panels, SMA 6K inverter) with a micro inverter system (IQ8+). All I have asked was to upgrade my string inverter because I think they're seeing a sales potential of installing 24 micro inverters. What caused the whole issue was that I wasn't getting any production due to an arc fault issue. Upon discovery (nov 2022) of this issue, I was instructed to reset the faults until someone came out to fix it...that was July 27 2023. Long time, no? POOR POOR Service. So now I'm in limbo waiting for some decision whether Sunpower or the original installer, Photon Brothers, will fix the workmanship and design oversight. It seems like a long time to have this resolved but I think the majority of the problem could be quickly remediated with an upgraded string inverter, not the installation of 24 micro inverters. Also, when the arc fault issue was addressed, the 3rd party repair company sent out by Sunpower didn't reinstall my critter guard and now there are gaps that will need to be addressed as well.

Nice video. My recently installed system includes Hoymiles microinverters. I am now thinking about ordering a spare microinverter to ensure compatibility in case one needs to be replaced in the future. Your argument for string is compelling. if my microinverter system fails, I may convert it to string. For now, I am hoping for the best regarding longevity.

Your thinking isn’t far off from mine with one difference. I am looking to build my system with a ground install. The cost of replacing a roof that is supposed to be every 10 year is already expensive, but to have a roof system removed and then re-installed after a roof replacement is a big added cost in that labor. But to the point I am planning on doing a battery storage with a sting system.

Hi... Just watched your video, thanks it was very informative. So I was sitting on the fence trying to decide between Microinverters and String Inverters, now i can say I'm still on the fence. The reason for my statement is I purchased a 5 KW solar system when my house in Mexico was being built. The current system has a String inverter and at full capacity. So to add capacity the original installer wants to add a net new 6KW inverter. I have been advised by another company to leave the old system and just add new Enphase Micoinverters for the net new capacity. How would others handle this. Add a new String Inverter? Can you have two string Inverters? Or just add Microinverters Enphase that claim you can do add on KW as required. Opinions please.

Great video and well reasoned. I very much like that the discussion was based on reliability and practicality of service

What about the rapid shut down requirement still in effect? Or per panel monitoring? For a basic string install, without panel monitering, someone should invent an MC4 compatible pigtail or splice that would have a plug-in for a wattage tester routed to the frame of the panel. This way you'd still have to go on the roof with a wattage meter but not have to lift or disconnect any panels to check each. Maybe take 3 minutes each to troubleshoot a problem.

heating issue is everywhere with solar technology especially inverters, what r your thoughts or experience about the IP65+ rated inverters?