Tel Aviv, Israel [UPI] Installing a residential solar energy system has become a little easier over the past few months, thanks to a company whose Web site lets customers compare contractors’ bids. You still have to do your homework: Does your state have a tax incentive plan? How much sunlight does your roof get? Do you want regular photovoltaic panels installed, or do you want to put in shingles made of solar material? … For consumers, the service is free.