diy solar

diy solar

Can I use a 5yr old 35volt 250watt panel to charge USB devices?

chrishdunn

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Feb 13, 2022
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Hi, I'd really like to get into solar energy and want to start off in a low key DIY way. The following panels have come up for sale locally (south coast of UK) ...

Used panels all factory tested 250 watts in good condition 35 volts. 100cm x 170cm. 5 years old. £35

I'm thinking of getting one panel and mounting on my shed roof. I'd like to use it to charge up my USB devices (phones and USB portable phone battery/recharger etc).

I've seen some solar panel controllers with USB sockets for about £10 .... could I use something like this and avoid using a battery as part of the system?

Amy advice greatly appreciated.
 
You could, but I would add a small, old, car/motorcycle battery to "stabilise" the lot.
Say the panel gives you 180Wh for most of the day. Your average USB charger will probably draw some 18W - likely less, but for argument's sake.
You can power 10 of them at the same time.
Now, if you actually wanted to do that, the USB socket(s) on the controller would fry, it would be better to add more ports... from the battery.
 
For that use just about any battery you could scrounge up would work, no matter how small or worn out. A used car battery, a battery from an old UPS, etc. While normally they wouldn't work for solar your demand is so small it doesn't matter.
 
Another candidate for EcoFlow, Bluetti, or Jackery.

That is a far cry, price wise, from what the OP is asking about.

I don’t see why the original idea won’t work and cannot understand why there would be a problem with boards frying etc. The solar charge controller should be rated to handle 40V but that’s not hard to find at a low price point.

Yes, it’s very overpowered for the intended application but should work fine. Your USB devices should be fully charged early in the solar day.

Sounds like a good way to get started with solar at minimal investment, @chrishdunn

Give it a go and report back.

One warning, this may lead to an insatiable desire for bigger and better systems. ?
 
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