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Solar Shed mega hobbyist. Finally a HN topic I can contribute to. I've spent last few years trying to build out my solar shed mainly to have auxilary power to

Solar Shed mega hobbyist. Finally a HN topic I can contribute to. I've spent last few years trying to build out my solar shed mainly to have auxilary power to charge weed whacker, leaf blower, power lights, power a camera, etc. Just basic 12v power. The number one lesson is to 4x your power needs. 4x your watts and 4x your battery amp hours. Don't cheap out on charge controllers. There's never enough sun light to fully charge your batteries and your panels are never at the right angle to maximize sunlight. Especially in less solar friendly areas like Michigan. Lead acid is fine if you over compensate with panels. Lead acid will last longer in the cold than LiFEP04. Die hards will say you cant charge LiFEP04 in winter but I do. I accept the fact that my batteries will degrade faster. When you can build your own packs, its a lot easier to find which single set of cells went out and cheaper to replace. Its a risk I accept. If you are starting out, get a 200 Ah/hr LiFEP04 battery and 400 watts solar. Its a very good starting point for 12v and gives room for expandability. Avoid foldables. Avoid Harbor Freight. Avoid Jackery Solar Panels. You need Quality Panels. If you wanna learn more, check out Will Prowse https://www.youtube.com/@WillProwse https://www.youtube.com/@WillProwse

carapace 3y ago
> Avoid Harbor Freight. Why? I'm just starting out with solar power and I got a 100W panel set (4 x 25W with a charge controller) and 35Ah battery from HF just to try it out and so far it seems fine.
- tiahura 3y ago
  The cheap junk on Amazon is much better.
  - eyegor 3y ago
    This is not generally true. Amazon is plagued by drop shippers now and as a result most of their solar junk is many years old warehouse stock. Harbor freight tends to be better. Ex: https://youtu.be/W-fgI6Kyy2I https://youtu.be/W-fgI6Kyy2I
- naikrovek 3y ago
  every single thing I have ever purchased from Harbor Freight has yard test ceased to function or physically broken after the first serious use. every. last. thing. ~25-30 things between myself and my family & friends. all of us have had the same results. sure, they'll often replace the thing free of charge, but that just addresses the money - my time is valuable, too, and going back and forth to HF all the time just got really old. no more.
  - naikrovek 3y ago
    I have no idea at all how I made that typo, or how I missed it as I proofread multiple times.
serf 3y ago
>Die hards will say you cant charge LiFEP04 in winter but I do. lots of marine-use lifepo4s have heaters on board and they're not a lot more expensive, and it's not too hard to diy something to an existing pack, either -- although of course it constitutes yet another draw.
VygmraMGVl 3y ago
Heads up, the danger with charging LFP at low temperature is that you will begin lithium plating. While this is a driver of degradation of LFP batteries, it's also a safety risk as lithium plating can lead to dendrite formation, internal shorts, and thermal runaway (i.e. fire). Contrary to popular belief, LFP is not immune to thermal runaway. While LFP batteries do release less heat than Nickel based cathode chemistries, they can still cause a building to burn down when you have 200Ah or more.
Scoundreller 3y ago
> Die hards will say you cant charge LiFEP04 in winter but I do. I think an issue in Michigan could be depleting your lead acid batteries and then freezing too, no? But should be fine if they get some occasional trickle charging and no real draw (gotta clear the snow off the panels here and there over winter)
rambambram 3y ago
> Avoid Jackery Solar Panels. Can you explain? I bought the solarpanel seen in the article and also have their Explorer 240 portable power station. So far I used it only slightly and it seems to work. Any specific things I have to keep an eye on with Jackery stuff?
xinayder 3y ago
I was about to ask how's the cheap solar charge controller working out then I read that it's not as good. I had one of these back home to power my hydroponics system, using a 20W solar panel. It worked "well" until there were cloudy days that the charge controller couldn't simply provide enough output to charge the battery. We used a normal car battery for that. After a few days the battery was dead because it wasn't being charged, so we decided to scrape it and run our hydroponics connected to the grid instead. If you're feeling adventurous, there is a MPPT chip that you can use for your electronics projects (though the only time I tried it I managed to burn the chip and couldn't find it anywhere in local stores, buying from AliExpress would take months to arrive) is the LT3652, though it's rated for 2A only. I believe you can find bulkier chips for higher PV wattage. EDIT: > The number one lesson is to 4x your power needs. 4x your watts and 4x your battery amp hours. Don't cheap out on charge controllers. I have installed a PV system on my home back in 2019 and the rule of thumb we found out as well is, if you're building a PV system for a house and use inverters, you should also not go cheap on inverters (i.e. go for cheap chinese brands). We have a Fronius inverter and it works wonders, much better than the other cheap brands and it has a lot of interfaces you can use it to retrieve data from. Another useful thing, if you buy an inverter rated for, say, 2kWp, you can safely overdesign your system to provide at least 20% (I don't remember the exact percentage) more power than the peak wattage your inverter supports. Reason for this is that because you can't predict clouds and bad weather, having a few extra panels will compensate the performance loss and will make sure you're always running at peak performance. It will also help a lot during off-peak hours. Of course, the extra panels won't magically bring you to peak performance if you have a very cloudy, dark day. But if you have some clouds, you can get a very big performance hit and you can compensate that by having more panels than your inverter is designed for. So, for example, if the inverter is designed for 2kW, you can build your system to produce 2.4kW. Another suggestion is to split your arrays in as many strings as your inverter suggests. They will operate like if they were independent systems, so if you have cloud covering one string, bringing its output power down, it won't affect the other string (assuming the cloud is only covering one of the strings). If they were under the same string, any shade on any of the solar panels would severely affect the output of that string.

carapace 3y ago

> Avoid Harbor Freight. Why? I'm just starting out with solar power and I got a 100W panel set (4 x 25W with a charge controller) and 35Ah battery from HF just to try it out and so far it seems fine.

tiahura 3y ago
The cheap junk on Amazon is much better.
- eyegor 3y ago
  This is not generally true. Amazon is plagued by drop shippers now and as a result most of their solar junk is many years old warehouse stock. Harbor freight tends to be better. Ex: https://youtu.be/W-fgI6Kyy2I https://youtu.be/W-fgI6Kyy2I
naikrovek 3y ago
every single thing I have ever purchased from Harbor Freight has yard test ceased to function or physically broken after the first serious use. every. last. thing. ~25-30 things between myself and my family & friends. all of us have had the same results. sure, they'll often replace the thing free of charge, but that just addresses the money - my time is valuable, too, and going back and forth to HF all the time just got really old. no more.
- naikrovek 3y ago
  I have no idea at all how I made that typo, or how I missed it as I proofread multiple times.

serf 3y ago

>Die hards will say you cant charge LiFEP04 in winter but I do. lots of marine-use lifepo4s have heaters on board and they're not a lot more expensive, and it's not too hard to diy something to an existing pack, either -- although of course it constitutes yet another draw.

VygmraMGVl 3y ago

Heads up, the danger with charging LFP at low temperature is that you will begin lithium plating. While this is a driver of degradation of LFP batteries, it's also a safety risk as lithium plating can lead to dendrite formation, internal shorts, and thermal runaway (i.e. fire). Contrary to popular belief, LFP is not immune to thermal runaway. While LFP batteries do release less heat than Nickel based cathode chemistries, they can still cause a building to burn down when you have 200Ah or more.

Scoundreller 3y ago

> Die hards will say you cant charge LiFEP04 in winter but I do. I think an issue in Michigan could be depleting your lead acid batteries and then freezing too, no? But should be fine if they get some occasional trickle charging and no real draw (gotta clear the snow off the panels here and there over winter)

rambambram 3y ago

> Avoid Jackery Solar Panels. Can you explain? I bought the solarpanel seen in the article and also have their Explorer 240 portable power station. So far I used it only slightly and it seems to work. Any specific things I have to keep an eye on with Jackery stuff?

xinayder 3y ago

I was about to ask how's the cheap solar charge controller working out then I read that it's not as good. I had one of these back home to power my hydroponics system, using a 20W solar panel. It worked "well" until there were cloudy days that the charge controller couldn't simply provide enough output to charge the battery. We used a normal car battery for that. After a few days the battery was dead because it wasn't being charged, so we decided to scrape it and run our hydroponics connected to the grid instead. If you're feeling adventurous, there is a MPPT chip that you can use for your electronics projects (though the only time I tried it I managed to burn the chip and couldn't find it anywhere in local stores, buying from AliExpress would take months to arrive) is the LT3652, though it's rated for 2A only. I believe you can find bulkier chips for higher PV wattage. EDIT: > The number one lesson is to 4x your power needs. 4x your watts and 4x your battery amp hours. Don't cheap out on charge controllers. I have installed a PV system on my home back in 2019 and the rule of thumb we found out as well is, if you're building a PV system for a house and use inverters, you should also not go cheap on inverters (i.e. go for cheap chinese brands). We have a Fronius inverter and it works wonders, much better than the other cheap brands and it has a lot of interfaces you can use it to retrieve data from. Another useful thing, if you buy an inverter rated for, say, 2kWp, you can safely overdesign your system to provide at least 20% (I don't remember the exact percentage) more power than the peak wattage your inverter supports. Reason for this is that because you can't predict clouds and bad weather, having a few extra panels will compensate the performance loss and will make sure you're always running at peak performance. It will also help a lot during off-peak hours. Of course, the extra panels won't magically bring you to peak performance if you have a very cloudy, dark day. But if you have some clouds, you can get a very big performance hit and you can compensate that by having more panels than your inverter is designed for. So, for example, if the inverter is designed for 2kW, you can build your system to produce 2.4kW. Another suggestion is to split your arrays in as many strings as your inverter suggests. They will operate like if they were independent systems, so if you have cloud covering one string, bringing its output power down, it won't affect the other string (assuming the cloud is only covering one of the strings). If they were under the same string, any shade on any of the solar panels would severely affect the output of that string.