Installing a solar power system in your home is a green initiative and good for the enviroment. Doing this entitles you to what are called 'Renewable Energy Certificates' or in short RECs. These certificates are like any other commodity and are traded similarily to shares on the stock market.
For example, when installing a 1.5kW solar power system you automatically get 31 certificates. Though as of right now the government is offering five times more certificates to people who act now. In the case of a 1.5kW system you will receive 155 certificates! At todays rate of $36 per certificate that would mean you will get a rebate of $5580. This is a great insentive to buy a larger system and in the long run save you money, not to mention save the enviroment.
I have found that at the moment the sweet spot is a 2kW system, that is what most people are having installed.