[Felz]

I'm not sure how South Australia works, but I think in general you pay for the cost of electricity generated (here going to zero) AND for the infrastructure required to get it to your house.

In part that's why rooftop solar is hazardous for a grid in high amounts- you don't pay the infrastructure price half the time, but the infrastructure still has to be there for you.

[cperciva]

Indeed -- so called "net metering" ignores the fact that the costs are driven by both consumption and capacity. Providing a 400A supply to a house is expensive even if you never draw any power, because the utility has to be ready to provide the power.

[ZeroGravitas]

The reason for net metering (other than it being a cheap hack to take advantage of just rewinding a standard power meter) is that the energy from the houses is valuable to the grid in lots of ways (e.g. in reducing peak generation and transmission demand).

It doesn't ignore those costs you mention, it just also doesn't ignore the benefits. In some jurisdictions the benefit exceed the money the householders are being paid (it varies depending on how dirty the grid is, when peak load happens etc.).

For whatever reason, like negative prices, this attack on net metering appears to resonate well with people who don't like renewables, but it's just a talking point from utilities who see the ability to increase their own profit by taking but not paying for that benefit via political shenanigans.

Apparently the idea that electricity can be differently valuable at different times of the day or year is something that ordinary people are insulated from, so paying an average seems normal, but getting paid an average seems crazy. But it's not something being argued against from a wider economic standpoint of efficiency, as it is literally a good thing, that's why people proposed it in the first place and continue to support it.