Solar panels are not only great for the environment, but they can save you money. The price for solar panels has decreased and the efficiency has improved. Congress has also extended a 30 percent federal tax credit for installation through the end of 2019.

With all these pros, solar panels are a no-brainer. They pay for themselves over time. Yet it is still important to consider the following questions before pulling the trigger.

Where does your roof slant?

Roofs facing south are positioned right where the sun hits. They produce solar power more effectively than roofs facing north where the sun doesn’t hit. Ruling out north-facing roofs is very common. After a south-positioned roof, the most desirable angles are west and then east.

Does your roof get shade?

A roof can be facing south, but if it gets shade from trees, hills or buildings then it can be a problem. Solar panels need maximum exposure to the sun for ideally five hours a day and shade hinders that.

How big is your roof?

Every 100 sq feet requires 1 kilowatt of solar panels. For example, a 5-kilowatt system would need 500 sq ft on your roof.

What angle is your roof at?

Solar panels require a roof angel of about about 30 to 45 degrees, but can be less with the help of tilted racks. Make sure your roof is not too steep or it will have trouble getting sun on the far side.

What type of roofing do you have?

The type of roofing you have is important to determine how the solar panels will be installed. Asphalt shingles or corrugated metal roofs are very simple to install solar panels. Slate or tile roofs can be more complicated.

Wood roofs are a fire hazard. When it comes to solar panel installation, this will be determined based your jurisdiction.

How old is your roof?

Roofs should have at least 30 years of life left for solar panels to be installed. Things will get more expensive if you have to temporarily remove the panels to replace your roof.

What size solar system do you need?

Solar panel salespeople will sometimes try to sell you larger systems based on optimism. Figure it out yourself by using the NREL’s PVWatts® Calculator