Aliexpress "120W" foldable solar panels

[hojnikb]

Anyone used one of these foldable solar panels from aliexpress?
https://www.aliexpress.com/item/1005004833781195.html?gatewayAdapt=4itemAdapt

I'm interested in how much output are these actually capable. I'm guessing 120W is a tad optimistic 

[Jackster]

Probably lucky to get half the rated output in perfect conditions...

[hojnikb]

Probably lucky to get half the rated output in perfect conditions...

I was thinking the same thing. Considering the rough area of the actual solar cells (i'd say about 0,4m2) and ~15% efficiency would yield 60W in good conditions. Guess i'll have to find out, they're cheap enough to try

[bidrohini]

I think it's better to purchase from dependable sources like sparkfun and dfrobot.

[hojnikb]

I think it's better to purchase from dependable sources like sparkfun and dfrobot.

Not exactly viable for us outside of US...

[bidrohini]

I think it's better to purchase from dependable sources like sparkfun and dfrobot.

Not exactly viable for us outside of US...

Yes, true. I am also from a country in south-east Asia. But here we have some official distributors of sparkfun and dfrobot. We can source products from them through distributors. You can check if there is an official distributor in your country.

[trobbins]

Considering the rough area of the actual solar cells (i'd say about 0,4m2) and ~15% efficiency would yield 60W in good conditions. Guess i'll have to find out, they're cheap enough to try

What tests have you done so far?  What testing are you capable of doing?  Do you have any standard cells or commercial modules, or a local meteorological station that reports insolation that you can then use on a sunny mid-day, along with Isc and Voc?

[hojnikb]

Considering the rough area of the actual solar cells (i'd say about 0,4m2) and ~15% efficiency would yield 60W in good conditions. Guess i'll have to find out, they're cheap enough to try

What tests have you done so far?  What testing are you capable of doing?  Do you have any standard cells or commercial modules, or a local meteorological station that reports insolation that you can then use on a sunny mid-day, along with Isc and Voc?

No, i don't have any standard cells unfortionally. My plan is to use this as electric scooter charger during summer days. I got the product, but currently can't really use it, because we don't see much sun these days. I'm planning on testing power output when there's good sun, along with voltages and current.

[trobbins]

Recharging any battery, and especially LiIon, requires very carefully designed and hopefully redundant protection against over-voltage and over-temperature - otherwise you risk a lot.

[hojnikb]

Recharging any battery, and especially LiIon, requires very carefully designed and hopefully redundant protection against over-voltage and over-temperature - otherwise you risk a lot.

My plan is to use CC-CV boost regulator like this https://www.aliexpress.com/item/1005005111717631.html?spm=a2g0o.productlist.main.1.1d1213d03Y2uol&algo_pvid=aacbcef2-9f66-4bf3-b425-fbfea926070b&algo_exp_id=aacbcef2-9f66-4bf3-b425-fbfea926070b-0&pdp_ext_f=%7B"sku_id"%3A"12000031700308508"%7D&pdp_npi=2%40dis%21EUR%2112.52%218.76%21%21%21%21%21%40211bf49716742915205774206d06eb%2112000031700308508%21sea&curPageLogUid=E4mtDPNxtn1I

and rely on BMS to do the cutoff, once the battery is fully charged. It's an electric scooter, so it has a pretty decent BMS built in already.

[uer166]

rely on BMS to do the cutoff, once the battery is fully charged

This plan couldn't be worse. BMS cutoff is above a safe cell voltage and is only to be useful in case of a catastrophic charger failure. Get a real charger with accurate CC/CV controls, and set it to exactly the correct voltage that the battery expect. In fact the one you linked is capable of doing it.

[hojnikb]

rely on BMS to do the cutoff, once the battery is fully charged

This plan couldn't be worse. BMS cutoff is above a safe cell voltage and is only to be useful in case of a catastrophic charger failure. Get a real charger with accurate CC/CV controls, and set it to exactly the correct voltage that the battery expect. In fact the one you linked is capable of doing it.

That's exactly what i'm planning on doing. Solar panels alone won't charge the battery anyway, since they have too low of an output voltage.

As for the charger; the one i ordered above does CC-CV, but doesn't do cutoff to my understanding. I dont think there are 10s charger boards out there that would do CC-CV and cutoff. Especially not ones that can run off a solar panel. If there are any, a link would be great.

[uer166]

Ah, by cutoff, you mean "stop charging". No BMS would do that unless you're abusing it. There really is no need here, you can keep the battery on CV indefinitely with little wear-out. One of the best things you can do is drop the CV setting to less than 4.2V, say do 4.1 or 4.0 instead. That will increase the cycle lifetime massively.

[hojnikb]

Ah, by cutoff, you mean "stop charging". No BMS would do that unless you're abusing it. There really is no need here, you can keep the battery on CV indefinitely with little wear-out. One of the best things you can do is drop the CV setting to less than 4.2V, say do 4.1 or 4.0 instead. That will increase the cycle lifetime massively.

Cool! I was thinkin of setting something like 40.5V or thereabouts. Original pack is rated for 42V, but original charger and BMS is "locked" to 41 to increase cycle life. So i guess setting to 40-40.5V would mean that charge rate when that voltage is hit would gradually taper off. Since i've left 1,5V before cells are actually full, i guess i should be good to go. It's not like its going to be plugged in with days on end.

As i've said, i'll post actual numbers when i get the board and when we get some actual sun over here 

[trobbins]

If there is a risk of overcharge to the point of thermal runaway (due to available PV power still being absorbed by battery even when all but one cell is full) then imho you need thermal protection and individual or group voltage sensing protection.

[hojnikb]

If there is a risk of overcharge to the point of thermal runaway (due to available PV power still being absorbed by battery even when all but one cell is full) then imho you need thermal protection and individual or group voltage sensing protection.

This is already built into the BMS already.