Rebates and price subsidies for installed solar panels are ways to help reduce greenhouse gases. In practice they are expensive and inequitable. They are examples of government directed expenditure with all the economic inefficiencies that this brings. It costs a lot to administer rebates and it may be better for the environment to spend money on hot water heaters or wind turbines or insulation or … than on solar panels.
It is inequitable because a person who has the capital to spend on solar panels is subsidised by an increase in electricity prices of those who cannot install panels.
There is another simple economically sound solution for governments who want to encourage green investment. Instead of giving rebates give the equivalent money to people who produce fewer greenhouse gases but require them to invest the money on ways to reduce greenhouse gases. These people will choose the most economically sound investment. It is equitable because those who produce the fewer greenhouse gases are the ones being subsidised.
This approach will deliver at least twice the reduction in greenhouse gases for the same amount of money when compared to rebates and subsidies.