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What to do with surplus solar power in an island solution? (lemy.lol)

submitted 2 days ago by greenbelt@lemy.lol to c/asklemmy@lemmy.ml

30 comments fedilink hide all child comments

What happens if the sun shines onto your solar panels, and you have too much power. I guess you could cover the panels with a blanket in such a case, but that would be manual intervention ....

Do you need to consume all electric power you generate? Ways of wasting power include ... heating water or electrostatics.

Most people would put surplus power they produce into the grid, but this is connected to government / cooperate regulations and paperwork, some would like to avoid that.

An island solution with solar panels is not connected to the power grid at all...

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[–] daannii@lemmy.world 2 points 2 days ago* (last edited 2 days ago) (3 children)

I heard of an interesting green battery.

So you get an elevated water tank.

Excess energy is used to pump water into the tank.

This stores the energy as gravity force.

When you need more electricity than the panels are providing, water is allowed to run down into a ground level tank that rotates turbines on its way down.

A battery that won't ever go bad or lose its capacity.

Turbines will likely need maintenance at some point though.

I imagine it a bit like those old wooden water wheel mills.

Almost like we had good simple methods a long time ago. They just need a little updating.

[–] itsprobablyfine@sh.itjust.works 4 points 1 day ago

Google pumped storage. This is what most grid scale energy storage is. It's the concept behind hydroelectric dams as well

[–] ObM@lemmy.world 1 points 1 day ago (1 children)

It’s a nice idea but impractical. Energy = mass x gravity x height

Say 10 tonnes of water pumped into a massive 20m high tower… E =10000x9.8x20 Joules. ≈ 2 mega joules.

Theres 3600 joules to a watt hour so dive that and you get:

≈ 550 watt hours (0.55kWh) of storage (assuming perfect efficiency of the turbines). About the same a half a dozen big cordless tool battery packs.

[–] daannii@lemmy.world 1 points 1 day ago

You only use excess energy that would otherwise go nowhere. I'm sure there are ways to make it as efficient as possible. But even if it's not highly efficient, it's a low carbon footprint method that is more sustainable than lithium batteries.

But yeah there might be other ways of storing energy. Maybe winding mechanics. Idk.

[–] Xavienth@lemmygrad.ml 1 points 1 day ago

You don't actually get that much storage doing this unless you increase the scale by a couple order of magnitude. At which point you're basically describing building a dam in practical terms.