by the way, you almost kill the rest of solar videos in terms of domestic application as your layout, explanation & calculation are so organized, clear & easiest to understand!!!
Your videos are getting better, ah... but your calculation is scaled impractically high. Very few people install storage and solar for a 10kWh/day load based on winter loading. Let alone with 3 zero-sun days worth of buffer. Its usually just too expensive to do that. Among other things, 2/3rd of the system's output will wind up being curtailed (thrown away) 8 months out of the year from over-production. Literally thrown away due to over-production. Between roughly mid-March to mid-November or so, only roughly 3kWp (p = installed nameplate) of solar is needed to handle 10kWh/day in consumption, for example. That's less than 1/3rd the amount of solar you specified. And instead of 30kWh worth of batteries to cover 3 days of poor weather most people will only cover 2 days. You get the 3rd day just from solar accumulated over the prior 2 days. 20kWh of storage rather than 30kWh. Even a bit less. 15 kWh of storage for 10kWh/day of consumption is far more typical (a 2 day buffer inclusive of solar accumulated over those 2 days). For winter most people who live off-grid make due with less power, and they use a supplemental generator. The reason is simple... no amount of solar and battery is going to cover you across a week-long storm. You need to have the supplemental generation anyway. The goal is thus to minimize fuel consumption during winter rather than eliminate it entirely. Eliminating it entirely is almost impossible in most locations. -Matt
great vid as always, but one thing i think was missed: you originally used the lowest sun producing month of December to start your calculations, but then when you broke down your load, you included 3 hours of AC. AC wouldn't be used in winter time, so if it's being used in summer time you'd have way more sun, meaning less panels. so maybe there needs to be a different calculation because AC sure used a LOT of energy :)
Right, you might save some because you wont be using AC. You will also be a lot more indoors, and use more power that way. But still, you got a valid point.
Central air and the pool in summer uses 5 times as much electricity as my natural gas furnace in winter. I keep a 10,000 btu window air conditioner in the basement that could be installed in minutes just in case.the only issue is that even then I would not be able to run that air conditioner while using the well pump or running the pool.
I currently have have 9 270w panels on the ground. I run two rack batteries down to 85% overnight and they charge up in a few hours in the morning even with part shade on some panels. I will be putting 12-14 270w panels on my shed roof and eventually I will be using a total of eight 48v rack batteries. Plus grid connect for back up power on extended cloudy days as I have a larger grid connect system as well. I personally go the other way around and size the inverter I require then the batteries for extended days, I go for at least 5-7 days back up and not 3. Then I size the solar array to suit. There will be excess produced so I can run my electric got water system off solar on a timer a as well during the day. Fully off grid I would the same. Always buy more than you calculate to create a buffer. I'm the example in the video I would buy 4 batteries and also a bigger inverter/charger and more panels. Nothing wrong with oversizing. The argument for cost is irrelevant. This is someone I wouldn't penny pinch on
I subscribed as most of my questions are in his video library I recently from a single 100 watt Renology panel cheap charger controller on the roof of my 4x4 suv One year later i peiced together 5000 watt pure sine wave with auto selection up to 48 volt also three large 400 watt panels that seem to produce 49.5 volt on cloudy days my smaller panel is 215 watt also puts out ,49.5 Volts with a smaller capacity ~ i can't afford to blow up my dreams now ( On roof of my 23' travel trailer only two fit currently thanks in advance for any suggestions or comments
I live in a snow belt in a semi-rural area of 20 acre lots. When the power goes off we are low on the list because of low population density. All I want is to live comfortably when the power goes off. I do have natural gas which never goes out but running just one of my two trifuel portable generators 24 - 7 is not a good idea considering wear and tear and fuel cost. I am installing 12,000 watts of battery backup so that I only have to run generstors a couble hours a day when the power is down. Next year I will put in 2400 watts of solar to run some of my usage year round which Which should cover the solar cost in 4 years and the battery backup in another 6 years. Basically it will be an insurance policy to be able to live comfortably during outages that will pay for itself over time.
7 mths ago I tossed up a 2kw panel/10kwh battery system and your numbers if you do the work yourself is almost identical to my experience. About 10yrs it will return my money, just about when I expect to start to replace parts. The comfort of having it to be a backup when the Grid goes down is very nice.
Sizing based on battery size is over sizing. On a daily basis, you do not need to generate battery capacity energy. Maybe generate daily requirement including loses. This would reduce cost of PV array. Array may be adjusted ups to reduce recovery time after days of autonomy.
In general, whatever you need comfortably to make it through the night with a bit of a buffer, I have 10kwh of batteries for a 2kw set of panels....and it is really close to the number...15kwh for 5kw of panels in my real world experience would be a tad undersized....I would advise 20kwh of storage tbh.
Personally I have the Grid for a backup to my Solar and still run my 240v AC outside unit off the Grid, if I was off grid and using a generator for a backup....I would prob triple my system, but that is me.
I know the headline limits the possibilities of expanding the solar, but I guess you could expand the size of the panels if you bought one less battery ? In that case the likelihood of running ‘uninterrupted’ during 3 cloudy days in December would increase … am I right? Is the likelihood higher or lower ? What’s your opinion on this ‘total cost’ approach?
Hi! I love your videos but I'm confused by this one. The reference table gives us KWh/square meter/day. That's not the same thing as "sun hours", is it? I wish you had gone into more detail on that point.
It's beginning to make sense ( please correct me if I error ~my 100 watt modified sine wave is 12 volt only so 2~ 100 Ah batteries wired series parallel gives me 12 volts at 200 Amp gives me ,117% just shy of our safety margin?
I need help with the system I'm trying to build. I have and know the info for how much I use monthly for power. Just need help starting and figuring out how much of what I need pls help
I’m a bit confused. You can’t charge the batteries while they’re on use or load. So how can the batteries be charged during the day if I’m using the batteries to power my house?
Why not charge while consuming power? Of course it's possible. It's like a water tank. Rain from the gutter enters at the top and water drains from the bottom 😉
The battery has 3 days of autonomy. That means on day 1 you will use 5kwh, day 2 5kwh, and day 3 5kwh. Then the battery will get recharged from 0 to 100%. This is the worst case scenario for off-grid purposes.
Obviously it would not be that neat more likely you will have random days of full and partial recharge. But the spare power would just sit in the battery bank (just like cash savings in a money bank) waiting for the rainy days.
@@grahamjohnson4702 It gets thrown away. The charge controllers will curtail the solar, reducing the power output from the panels to exactly match your real-time loads once the battery is full. Excess power that the panels COULD have been producing is thrown away. So it will be able to keep the battery full until sun-down, but it can't use the extra power unless there is a load there to soak it up. This is how renewable energy works. You either have more than you need, or less than you need, but never exactly what you need. Always better to have more than you need. Instead of throwing it away, some people are able to leverage the extra energy by adding extra real-time loads to the system to soak up the extra energy. For example, a little crypto-currency farm (Mining monero, for example... but to be honest nobody ever makes enough money that way for it to be worth doing). If you have access to the grid you just push the excess to the grid. If you don't you can use the excess energy to heat water in your water heater, or heat a sand-battery for overnight home heating purposes, and so on and so forth. At least up to a point. So there are plenty of use cases for the extra energy instead of throwing it away, but those uses have to be constructed. Most people don't bother beyond heating up a tank of water or a sand-battery to help with overnight home heating needs. Theoretically... well, actually in practice, some greenhouses generate extra heat and inject it into the ground during summer and the heat then reduces winter operating costs. It can actually radiate back into the greenhouse over the entirety of winter. -Matt
Hello Sir. I want clarification, pls help me. my country, all the seven days getting sun light. (Not 3 sunny days as said in the video). So I have a doubt in the panel and battery calculation. If am using 300Ah/12 volt battery+ 760 Watts solar panel, can I connect 900watts load with lead acid battery.
Amp-hours is not really a measure of energy storage. Its amp-hours x volts. Presuming LiFePO4 batteries, you don't buy 12V batteries for this. You buy 48V (which is actually 51.2V nominal for LiFePO4, 16s) batteries. 5kWh of storage winds up being ONE 100Ah 48V LiFePO4 battery. That would be ONE EG4 LL or EG4 LifePower4 rack-mount battery. Around 100lbs. I'll reinterpret your other question as "How much solar to produce 5kWh/day". The answer is roughly 1.5kWp worth of solar panels in summer, and roughly 2.5kWp in winter. kWp = nameplate installed solar panels. Of course it depends on many factors, in particular where you live in the world, but those are rough numbers that work almost anywhere. Generally you just multiply the nameplate by 2 to 3 for winter and by 4 to 5 for summer to get the energy/day. 1 kW solar panel = 2 kWh to 3 kWh/day in winter and 4 kWh to 5 kWh/day in summer. Roughly. Something like that. Depends on where you live. So choose which setup you want. 1.5kWp worth of solar with 300W panels is roughly 5 panels. 2.5kWp worth of solar with 300W panels is roughly 8 or 9 300W panels. The 1.5kWp setup will be able to produce 5kWh/day of energy for roughly 240 days out of the 365-day year. A 2.5kWp setup will be able to produce 5kWh/day of energy for roughly 300 days out of the 365-day year. And less for the remaining days (winter storms, excess cloudiness, etc). -Matt
How do i maximise the inverter with 2 MPPT trackers without affecting the Voc. Have a LuxTek 5kW inverter (5SNA). 2 strings of PV modules one with 600W JA Solar panels and another with 450W panels. Worried about inverter max voltages.
PV1 has 1265W and 150.6V PV2 has 1765W and 155.5V Inverter is LuxPowerTek SNA5000WPV. Need more PV capacity but concerned about MPPT voltage limits on Inverter. Please advise
@@hamiltonkpasipamire7454 if the inverter can handle it, parallel the panels. BUT the inverter has to be able to handel the SCC short circuit of all panels. if a panel has 33Voc 30V mpp and 22A Scc 20A mpp (600W) and the inverter can handle 150V 25A you could put them all in series. because 4 times 33V open circuit is 132V => plus 10% safety magin => 145,2V open circuit is below 150V inverter capabilitiy. for the current nothing changes because in a serial string the amps keep the same like the individual panel. thats 22A short circuit. 10% safety margin => 24,2A is below 25A inverter capability. if the inverter can handle 80V but 50A you could put 2 panels as series strings and then parallel them with another series twin of panels. so you had 66V open circuit including 10% safety => 72,6V => below 80V. and the two paralleled twin strings would double the amps to 44A short circuit => below 50A inverter capability. still you need to take into consideration the battery voltage level. like 12V, 24V or 48V. you can all-parallel the panels, if 1.: the inverter is capable ( 22+22+22+22 = 88A short circuit) AND the battery voltage level is about +/- 33% BELOW the mpp maximum power point voltage of the panel. that would be about 18V for a typical 12V system. so panels rangeing from 17 to 21V mpp would fit well for a 12V with all paralleled panels. on a higher voltage stage like 24V you could never get a single watthour in your battery. so putting two in series for a string of 36V is the minimum. you can stack as many 36V strings in paralel as the inverter can handle. but you could also put 4 panels into a single string of 72V mpp. but always look for the open circuit voltage and take that into account with you calculations. a single 18V mpp panel might produce 21V open circuit. also never chose an inverter below the short circuit rating. it might fry.
You don't need to find how many batteries. If you buy an inverter which has a rating of 5kVA and 48V that means you need 4 batteries connect them in series simple. The Battery input Voltage is already mention when you buy a Solar Inverter. If it says 24V you need two batteries in series, 36V you need three in series and so on.
@@geoffreykaila depends, now if average sunshine hours in a day is 4 and the maximum PV wattage that can be connected to the inverter is 5000 watts, so that means your solar panels will generate 5000 watts * 4 hours (average sunshine) = 20,000 Watt-hours , Now since the inverter has a battery voltage input of 48 Volts and if we take 4 batteries each having voltage of 12V and 200Ah we connect 4 of them in series the total voltage will add up to 48 Volts , 200Ah, here the total energy of the battery will be 48V * 200Ah = 9,600 Watt-hours. So the total energy generated from our panels is 20,000 Watt-hours as compared to the total Energy of the battery which is only 9,600 Watt-hours which is clearly sufficient to charge the battery bank. 20,000 Watt-hours (Generation from Solar ) > 9,600 Watt-hours ( Total Energy of the Battery Bank). Hope this helps!! Cheers!
I design from the battery backwards and but as many batteries as I can. Then the inverter charger and then as many panels as I can fit. I didn't calculate anything. Just go as big as possible.. my inverter charger has AC in for charging even the sun doesn't shine