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this post was submitted on 17 Mar 2026
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Asklemmy
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Nothing happens, the controller will open the circuit and prevent the current from flowing.
Optimal solution is biting the bullet and getting batteries, the controller will prevent them from being overcharged, and you will need stored energy on an island.
You could try gravity storage like the other person mentioned but it's less efficient. During the day the solar panels power a pump/motor to move water/heavy object up high, and at night the water/object moves back down and powers a generator. There's a lot more loss since you're going:
solar energy>electrical energy>rotational energy>hydraulic energy/potential energy>rotational energy>electrical energy
and each transition will have losses due to friction and heat.
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 and pump will likely need maintenance at some point though. But they won't be using rare minerals or lithium.
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.
Google pumped storage. This is what most grid scale energy storage is. It's the concept behind hydroelectric dams as well
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 divide 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.
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.
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.