441 Are PV Optimizers Worth the Money (e.g. SolarEdge)? 

not sure but in general our 2022 solar panels and inverters show such string behaviour that 1 partly shadowed module kills the production from about 2500 Watt to 250 Watt and then 30 minutes later the same for the next string which is twice as big from 4500 W to 450 W caused by leaf tree. Each day the same time this can be observed where we moved from 1 bing string inverter to 3 smaller one phase and double string inverters which lead to 6 strings and therefore a much longer usage time of the full power . Our roof is now split into 6 strings instead 1 or 2 and the benefits are significant if you check the inverters string by string and not the inverters in general even though that will show the same effect . If you add a timelapse camera you can mark the lines of the shadow when the shadow is too big for the diodes and the power will be lost. I am not sure about the optimizers but the 4 different Growatt inverters we have had in the past 3 years for tests (like SPH series, 3000-S String, Mic 3000, Min 3000 and Mic 4600). But they also come at a price, which means the price of the purchase of 3 smaller versus 1 bigger but also the lower production cause 6 strings instead of 1 big one means lower string voltages and too low voltages means that the inverter will start later than the 6 times bigger one. 3 Watt is not enough for a 4,6 kW inverter, but 18 Watt sure. Not sure what the shadow optimizer inverter will cost or how big the benfits will be they can gain but it is not that easy. I had played a lot with the simulators like that pv sol premium which Valentin Software offers for free for 30 days but I was able to gain more and more Watt hours by the right inverter size and amount strings and of cause the sting cabling cause our strings are build up vertical cause a tree is spending shadow from 4 pm in the evening which is now not so much wanted than 30 years ago. But it took quite a long time to find solutions for each roof, one with the chimney and the tree shadow and a lower angle while the other has a steeper angle but also its own issues caused by a GAUBE of 7 m widthspan . Gaube looks nice but 22 years later more or less useless nowadays cause a 7 m long segment of the south roof is lost and also causing shadows in the morning and the evening on one or the other side. Hope to see the update video soon, but I guess it will take till spring. Meanwhile we will simply add more panels and another inverter which will help a lot to get the 20 kWp in Spring and maybe in 2 years the 30 kWp as maximum using the roof area better with small microinverters around the 2 chimney and lower areas where the greenhouse is which has a steel roof too. Gets a lot of shadow but 5,5 m width and 2 m depth will offer a spot for 5 big 525 Wp panels that can produce during summer full till 4 pm before autumn and winter will start the time of long shadows no one wants. 3 kWp here and 4 kWp there can make 5000 kWh even in shady situations if the microinverters can proctect these modules close to the chimneys. The Min series from growatt with 2 mppt has helped us a lot like the Min 4600 we could get for 600€ , but the smaller ones like the 1000 W inverters are getting expensive about 350€. Unfortunatelly the cheap chinese GMI inverters or the SGB or many others we have all tested are not really working fully and throttle caused by overheating. Only the more expensive western ones get it done right but at a higher price, lot higher price of about 360€ per 500W - but at least without throttling. Maybe hoymiles might be able to deliver a better performance and having the EU certificates like VDE AR 4015

@@typxxilps Your situation seems to be quite complex! I do not know the products you use. But the inverters must have built-in shadow management. Otherwise, they can react completely wrong (as it is the case at the beginning of your comment). If you need more and more small inverters, optimizers or microinverters might be the better choice, at least for the shortest strings. But still: If a shaded panel does not produce energy, an optimizer will not fix it.

Micro inverter and Optimizer The solar equivalent of Batterizer see EEVBlog

Hi, Andreas! It's been sad for me to see that you don't number you videos any more. It is a killer feature of your channel! Numbers make it so easy to navigate through your vids and I go through them a lot! Let's say I need the video about A6 GSM module, I would simply type 66 in your channel's search and here I have it. I hope you consider keeping on with this tradition! Cheers from Prague =)

@@romanalexandrov2880 I still number my videos. Only the last few get their numbers later...

Thank you. You are ahead of time! This video is not published yet ;-)

@@AndreasSpiess Hi Andreas, Would it be possible to add diodes to old solar panels that do not have them integrated in the panels?

@@Conservator. As you see they have to be placed on the front side. So if you can remove the glad, maybe it is possible.

Interesting paper. Maybe one day they add a few transistors inside the panels to switch each cell accordingly. Because with the current fixed bypass diodes, most of the loss comes from the panel. Which is also lost for the optimizer...

@@AndreasSpiess Thank you for the reply. The bypass diodes are an "economic compromise". When one cell goes on the negative region, its voltage is around -17 times that of the other cells. When adding them up, this makes for a negative voltage that activates the bypass diode. This means that 18 (or around that) are the maximum number of cells you can still protect with a single bypass diode. If I'm not mistaken, space applications put one bypass diode per cell, to avoid this problem and maximize power production. I suppose it would make the PV modules too expensive to do so. :P Transistors would be too complicated.

could you help answer a (hopefully very simple for you) question - adding several higher power (much newer) panels in series with the old ones I should get less than rated from the new addition, but something proportional to the new panel voltage * old panel current right? thank you

@@tjunkieu2b Thank you for your question. I will try my best to answer it. I think you are right: as PV panels age, they produce less current (but not that much less). If you connect a newer panel in series with an old one, they will have the same current for a given point of operation, but they might have different voltages. Would you mind explaining a little more? Are you retrofitting stand alone/DC grid PV for grid injection?

@tjunkie Yes, but there are issues with mixed modules in a string, and if at all possible one should not do so, or you can significantly shorten the life of the lower power modules as they will be possibly passing more current through them than they are designed for. Best to have the same modules in each series string.

That is what I wanted to show in this video. Microinverters are a good solution for small strings.

My pleasure!

You are welcome!

Thank you for your kind words.

Enjoy your installation. Solar is a lot of fun!

I agree!

It feels always good to see that an idea was right ;-)

Thank you!

You are welcome!

You are welcome!

You are welcome!

I currently test optimizers in an arrangement of four panels directing towards south and in a steep angle. I plan to add another 4 panels in the same direction but a different angle. 4 panels are not enough for a string for the Huawei (not enough starting voltage. So I might end up with optimizers in this configuration. At least I will test them.

You are welcome!

Yes, she is still happy…

So you can be her hero ;-) I am glad that I was able to contribute.

I also forwarded your video to engineer and architect friends who are working with solar. You are the hero to all of us. Thanks again for your hard work.

20mA indeed is not a lot for solar power systems where we try to produce MWh. But in your case, maybe it would be of benefit to find a space for an additional panel. This often is the better way.

At least you have a working solar energy factory now. That is the most important fact!

You and I are here for the same thing. I frequently encourage Andreas to focus on real world projects because, building stuff well is often remarkably difficult. I also keep encouraging him to use MicroPython on ESP32 instead of C/C++ ESP32 because MicroPython is both quicker an easier to work with, yet often just a performant-from the user's perspective-for many, many projects.

@Daniel: I found out that "Solar" people often do not come from electronics. So they believe their suppliers.

@@AndreasSpiess It's "found out" not "fund out". Pro Tip: compose in Google Docs to get grammar checking "on the fly" (automatically).

@@AndreasSpiess that would explain a thing or two ;) then again installers have access to hardware and putting up a small system to test shading wouldn't take them long but I guess many of them don't care that much. Luckily we have people like you that are willing to spend the time to show and explain how things work without marketing BS and I'm trying to do my part explaining "basic" electrical stuff to my friends.

@@AndreasSpiess In the US most of these installers are going to be traditional roofing firms that have added solar to the list of the things they install. As such, will have very little training in the theories and such. I suspect that this would be true of most countries/installers.

Thank you!

Glad the video was helpful!

Did you have "shadow compensating" MPPT? Also, did you have adequate bypass-diodes on your panels?

The forecast of the „optimizer guys in your case would be that you lose the power of the whole string. So if you lost all power during the shadow phase, the chance is that your panels do not have bypass diodes…

Good luck with your system!

You are welcome!

Cool! Sleep well. It must be late!

My pleasure!

Many installers are also "cheated" by the suppliers. Keep in mind: This is a growing market with many new entrants without deep knowledge. I would inform your installer, not punish him.

Welcome aboard the channel! For small systems, microinverters might be a good solution because string inverters usually need a certain startup voltage. For your large system, a string inverter is a good choice.

My pleasure!

Glad it was helpful!

Solar panels are like tattoos: You always want to get another one ;-)

@@AndreasSpiess Can't really tell, I have no tattoo ;-)

@@PhG1961 Me too. But I know lots of people who have a few of them ;-)

It's so interesting to see the progression in the PV world. I also started in 2006, with three Sharp 165Wp panels on a Mastervolt Soladin 600 inverter. That system would seem like a toy nowadays.

@@SolarWebsite Mastervolt is a really good brand. We have 10 panels for a total of 2.2 KW with an Infinity inverter. This brand does no longer exist, but it's quite good, so far, never had any issues.

You are welcome!

You are welcome!

I agree!

Very much so: single panel plug and play solutions are up for grabs now.

Absolutely. Cost of microinverters for a 3 panel system will be less than a string inverter. In addition, it is easy to install. But if you are going for above 1.5kW power like 3kW or more, they become expensive

Thank you!

I added a simple "divided by the number of panels" in my Grafana board. Now I can compare the cells and see if one creates problems. The only thing is that I do not know which one it is ;-)

Pretty much everything I've read and watched about optimizers says they are a waste or worse in most situations. Unfortunately, since the US NEC 2017 & 2020 electric codes require Rapid Shutdown on a per panel basis, the math changes a bit. If you already have to put an additional RSD module on a panel, maybe putting on optimizers with RSD and monitoring instead makes more sense since you are no longer adding more connections or modules in the chain.

Thank you! These diodes seem to be the standard for the last 10 years.

Yeah its a good idea on paper, but an incorrect installation, a factory defect, or like in most cases a bad connector tend to start these fires. Connectors failing are one of the leading causes of fires and when adding optimizers you triple the amount of connectors in a system. Not to mention that not all systems are equipped with such devices and they can fail closed leaving the system still energized. So in the end you have to train for the worst case scenario and treat each as it is live. The real solution would be to integrate into the panel but I don't see module manufacturers wanting to do that.

I do not know how dangerous it is for firefighters. As always, you have to hold both ends of a "battery" in your hands to experience a shock. Reading through recommendations for firefighters in this case, they list various things. None of them related to be electrocuted by the panels.

So enjoy your project! We love it even if it does no more cover our full needs because of the weather and the low sun.

That is a pretty big roof considering it is just one side! You can place 10kW panels easily on it Depending on latitude, climate and shading, you will get 30-50kWh/ day on average

Thank you!

I agree. You only learn with making mistakes. If you get it right, you already knew it before ;-)

Microinverters are a good choice for small systems, I think.

Thank you!

You are welcome!

Having them in parallel isn't perfect either. A shaded solar panel can become a current sink without a blocking diode. Although counterintuitive because a solar panel is a diode, it's only a very weak one and reverse current can cause it to fail. Moreover, the thick cables will cost a lot more than having a mini inverter behind the panel and using classic 230 cabling.

@@matthewmaxwell-burton4549 I agree and value the response! I have a mix of different 18V max mppt panels just for testing. I actually wire them up in parallel with a Schottky diode in series of each panel. I know not 100% efficient but there is a best approach which each situation.

With small panels, maybe more arrangements are possible. If you work with higher power you have to take the capabilities of the inverter into consideration. I like if my inverter and battery use high voltages because it generally reduces loss and reduces the needed copper.

Thank you for the hint about the Australian video. I thought I had it included in my comment, but I forgot it. Now it is there. And good luck with your inverter and battery...

Single panel monitoring seems to be important for many people. Professional installers know that panels do not fail often…

The monitoring is a nice feature but not needed. Even without it, the panels will function the same. Even if you manage to find out that 1 out of 15 panels is defective, the cost of optimiser would have been much more than the cost you saved by getting 1 panel replaced

My pleasure!

Thanks for watching!

Agree. On my installation, one if the panels failed after three months. It was easy to detect as you get power per panel. Our system has 3.6 kWp facing South and 1.5 kWp facing West (both different inclined roof), on one giant string. Hard to say whether this works better than two independent MPPT.

If you value the additional features of optimizers, you did the right choice. I only did not like when salesmen use the "single leave" argument.

Exactly, this line of “optimisers are all about shade” is typical of string manufacturers. It totally misdirects from the many other benefits of MLPE like many safety features, panel level visibility, simpler fault detection and repair work, higher efficiency, dc coupled storage, the list goes on. Making it all about shade, which is a confusing topic and difficult to properly compare, makes it simpler to push the traditional dangerous string inverters with uncontrollable high voltage dc.

@@cybersax2 Solar panels hardly EVER fail nowadays. Quality control is so good.

@@BrentHeberAusNZ Ooh, dangerous string inverters! It's still the same amount of kilowatts coming down the string, which will still kill you, whether DC or AC. Who needs panel level visibility? What fault detection. Solar panels almost NEVER fail nowadays.Higher efficiency? Any proof of this?

Sorry for scaring your cat;-)

Thank you!

the inverter tracks to the maximum global mppt, but obviously can't step up or down single panel voltage

If you look at the U-I diagrams of the panels you see, that the panels adjust voltage according the current. This effect is used by the MPPT.

Indeed, Dave went a slightly different way with two independent systems (one string inverter and the other micro inverters).

In your situation, I would go with microinverters.

My pleasure!

Indeed, like with motors, displacement is best replaced with more displacement ;-)

@@AndreasSpiess The saying in the US is. 'There is no replacement for displacement' ... :->

I think they know these facts, too…

Microinverters are ok for small systems with only one or a few panels, I think (we call them "balcony power plants").

Most of them are not specialist. So they go with what they are told :-(

I also learned that it is good if you know the topic ;-)

My pleasure!

The tilt indeed has a big influence!

I would not look back because your PV works. This is for people who have to decide and I wanted that the are not cheated.

I currently play around with microinverters as a "balcony power station". They are fun for one panel and very easy to use.

Thank you!

I agree!

Definitively they are improving! And it is important that we know what it means for us ;-)

Glad it works. I did not say, it does not work. I said it is not needed...

@@AndreasSpiess Yes sorry I didn't want to imply that! One thing occurred to me though.. for most applications isn't the selling point of the optimiser to convert directly to 230V AC at each panel? Not applicable in your own case, but I could then understand that it would shift and break up total losses from a central inverter to each optimiser so not quite as bad!

@@tolsen4893 These "optimizers" are called "Microinverters" (also covered in the video)

@@AndreasSpiess Ahhhhh! Sorry that makes sense!!

Thank you.

Thanks, will do!

Thank you!

I did not want to condemn optimizers! I just wanted to show a false claim. In certain cases, they are good. However, if the bypass diodes kick-in, also the optimizers do not get energy from this part of the string... I cannot control the optimizers. It is done by the inverter.

The diodes are inbuilt to the panel. If the panel is largely shaded, the diodes will be activated even before optimiser can do anything. Even if the optimiser manages to salvage some power, it will be in few tens of watts which is miniscule when comparing panels of 300-500W. Keeping 10kW in a single string is a serious risk of safety and highly expensive due to high amount of current flowing. Even if you can do it, you must avoid doing it.

I agree.

Strange behavior of the inverter. Maybe you contact the Huawei support. That is a strange behavior.

You are lucky you are far away from Europe. Here, energy currently is a very hot topic ;-)

You are right. Keep in mind that after a few weeks, most users only check the power every month or so. And only for the whole plant and a whole day... The risk of having electronics in the heat and humidity of a roof stays forever...

I agree, for small systems without battery, microinverters might be a good choice, particularly if the panels point into different directions.

Thank you!

I think you did a valid decision. This video is only focusing on one wrong claim of the industry. Your microinverters still work. So let’s hope this will continue for the next 18 years.

You are welcome!

You are welcome!

Glad you liked it!

Indeed, these are two different topics. But I know that a lot of "Makers" these days added "Solar" to their topics. Also because they sometimes are asked by their colleagues about their opinion.

@@AndreasSpiess a lot are probably interested in building solar as well! Including me. Just not enough time! :-)

Research and open eyes are always good ;-)

You are right. If you optimize for winter, south and steep is best. I added a few of those, too.

Vielen Dank für die Blumen ;-) Ja, ich habe früher an Unis und Fachhochschulen unterrichtet.

You are welcome!

You are welcome!

You are welcome!

@@AndreasSpiess Dave from EEVblog did a video about a similar topic, ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-AbxHoQF4ADk.html - i suspect his older inverter was not equipped with global-MPPT.

@@AdityaMehendale I saw this video, too. It must be something like that. I assume bypass diodes would not have kicked in with this small shadow.

I agree! Injustice tried to do all possible errors ;-)

Glad you liked it!

You're welcome!

Thank you for sharing your experience. You were happy that they replaced the device free of charge! Here they usually are not allowed to go to a roof just like that ;-)

Glad you liked it!

You are welcome!

I divide the power by the number of strings. Then I see if something is wrong (which seems to be very rare). But if you want this feature, optimizers or microinverters are your solution.