This gets into the other billing problem with domestic solar. In rough numbers, half of your electric bill is for energy, the other half is to pay for all the

This gets into the other billing problem with domestic solar. In rough numbers, half of your electric bill is for energy, the other half is to pay for all the grid and capacity. Billing is purely on energy consumption. The effect of this is that low electric users get subsidized by high electric users. When someone installs a domestic solar system they reduce their payments, but they still depend on the grid infrastructure. The system reaches its ultimate perversion when a grid tied domestic user achieves a negative bill. Not only have they been paid for their energy, they have been paid for the utility having a grid. You can solve this economic distortion by a couple of ways: • split billing into a grid-tie fee and an energy consumption charge: This accurately covers the solar houses, but it also raises the bills of the poor and cuts those of the wealthy (generally larger consumers). • only pay domestic solar producers half what you charge for power: This works out asymptotically for a huge producer where the grid portion vanishes, but it doesn't work for people reducing their consumption but maintaining a grid tie or selling a little bit. • put a surcharge on each watt of solar capacity: This works out accurately, but feels abusive. 1 watt of solar panel is going to make about 100 wHr of power a month. If grid-tie privilege includes a surcharge to cover the grid portion of 100wHr then this 1 watt solar panel user will end up paying the same for the grid as he did before. If a domestic solar installation is a net producer, it will end up getting paid for the energy and the grid fees will cancel. Even before we get to a point where the power company may say "no thank you" to a domestic user that wants to sell power at 1pm on a sunny day, we still need to straighten out the billing. The current system ends up with the utilities (and by extension all grid users) subsidizing solar installations by forgiving their grid costs. I'm in favor of that now, but in a future where our carbon emissions are under control the distortions will need to be smoothed out.