it's weird, but legal for some reason. Giving back energy to the grid can cost money. Shy of just stacking a bunch of batteries, what could I do with the spare summer sunlight?
It's stupid, yes, but there is a reason. The electric company pays to maintain the infrastructure. They trim trees and fix downed lines, and they pay for it by selling you energy.
Now, if you don't buy energy, you aren't using the lines. That's acceptable, because they know you might buy energy in the future, so maintenance is still worth the investment. But if you're selling energy bsck to the grid, you're using the infrastructure and they have to pay you for running your meter backwards. Even paying you a reduced rate for the energy you produce is a losing proposition for them.
Also, bribery is legal, and energy providers have a lot of money. They can afford to buy politicians, so if there's a way they can make it illegal to lose money, then they will. And they have.
But if you're selling energy bsck to the grid, you're using the infrastructure and they have to pay you for running your meter backwards. Even paying you a reduced rate for the energy you produce is a losing proposition for them.
It's a bit worse than that, even. If there are too many people sending too much energy back to the grid, the grid can get overcharged and blow up. So energy companies have to dump the excess power somewhere to keep the grid stable.
There are a lot of potential solutions to this problem. (Before anyone says Bitcoin fixes this, no it doesn't.) unfortunately, energy companies are currently taking the laziest and least efficient solution - pay business owners to run their factories uselessly in order to drain excess power from the grid, and pass the cost on to consumers.
Indoor vertical gardens (LEDs), heat storage (insulated water tank) and any other method of storing energy you'd like to explore (batteries can be myriad of systems/devices - exploring these are good investment for your mind and maybe (if successful) for your home)
BTW, where are you that it's OK to charge you? In my state (US), it becomes refund for any energy to you DO use from the grid
Usually it's in places where it's so unusual to feed back power to the grid that the grid isn't adjusted to it, or the local regulations aren't updated for it, so you either have to make sure you don't feed back power or you need a completely different electricity contract with higher connection fees so household solar can't pay back enough to cover the fees. It used to be a problem in parts of Sweden a decade ago, but now it's mostly fixed here.
It's never been a thing up until recently, and this change happened in the middle of a political voting/reform cycle thing. I am expecting this to be rectified in the coming year
My sister overcools her house so she doesn't have to run the AC at night (but she lives somewhere hot enough for that to matter - I can just open windows most nights).
I charge my electric car on it (which I guess is stacking a bunch of batteries). I'll also cook during that time to use the energy on that.
Running an aircon or refrigerator would be the obvious choices, but you could for example also connect an small electrical oven and dry some fruits or mushrooms in it... or get all fancy and bake your own bread.
I'll second heating water. A water tank is a battery. Alternatively, if you want to get really techy with it, you can make a refrigerator that runs on ice.
Basically, it's the opposite of a water heater. When you have extra energy, you freeze water. When you don't have any extra energy, the ice you made keeps your food cold. How you freeze the water doesn't matter. Most efficiently is a heat pump like a normal fridge, though.