Posted on

What to do with old solar panels

Using old solar panels

In my last post, I shared my brother’s journey to upgrade his off-grid home from the multi-decade-old original solar system to a new one that meshed with his needs in the modern age. But what did he do with the old panels?

The trouble with utilizing ancient solar panels is that they’re so much less effective than new ones that it often makes more sense to just replace them than to add them into a larger array. The panels don’t have to end up in the trash, though.

Instead, Joey came up with a clever hack that takes advantage of the panels with almost no supporting equipment. What’s the solution? He uses the old panels to pump water from his spring up the hill into a pair of large tanks. The result is free water pressure combined with enough storage to carry him through the dry summer and fall.


The setup

Water tank below a spring

The system starts when water gravity-flows from Joey’s spring into a 500-gallon tank. On the right, you see the original spring box, which he’s bypassed.

Inside the plastic tank is a float switch and a pump intake. The switch turns on the pump when water reaches a certain level then turns it off when the water drops to another level. Zero management!

Cooler turned into a pump box

Of course, the pump is fueled by the sun. That doesn’t happen quite by magic, though. Instead, Joey made a pump house out of an old cooler that keeps everything dry while also channeling noise away from the house. A more traditional electric box connects the solar panels and pump.

Water storage tanks

Water is pumped up the hill through pex tubing and into two 550-gallon tanks connected together. Then the water gravity-flows back down whenever Joey turns on his faucet.

The hill just happens to be high enough to provide 30 PSI!


What would he change if he had to do it over again?

Cat on a spring box

Joey installed his old solar panels on swivel mounts. Now, he wouldn’t bother — solar panels are so cheap, he doesn’t see the need to add fancy infrastructure to soak up every last bit of sun.

Otherwise, his water system is running perfectly! It’s even cat-approved.

2 thoughts on “What to do with old solar panels

  1. Good thinking, although he might have tried going with a ramjet water pump You can’t beat gravity as an efficient energy source.

    One of the arguments against going “all solar” is the disposal problem of spent panels..but a quick “orders of magnitude” estimate shows that it’s not really a problem– I forget the exact numbers, but given the total panel area required to power the whole country and a panel size of ~36x50x2 in, and a need to replace them every 20 yrs, the total voume going into the dump is dwarfed by the total annual US production of waste…..

    We don’t really even have a landfill problem, except locally near large metro areas. We produce something like 1000 cu miles of waste per century now, but with a total area of 19M sq mi, that’s nothing…and dumps are now required to have a plan to restore the land to park/recreational/natural area when filled up…The ultimate in recycling, so to speak.

    1. I don’t think Joey’s impetus was necessarily wanting to prevent waste so much as frugally wanting to use up the resources he had on hand…

Leave a Reply

Your email address will not be published.