Depending on where you live, buy solar panels power can dramatically lower or even eliminate your electric bill. It can also boost the resale value of your home, and many states offer incentives like rebates that make going green even more affordable.

You’ll save the most by buying panels in cash rather than leasing them. That’s because a cash purchase has the shortest payback period and provides the best long term cost savings, especially if you’re able to install your system on an area of your house with direct sunlight exposure.

Shine a Light on Savings: A Step-by-Step Guide to Buying Solar Panels

The Nerds explain how solar works: Solar panels are made of photovoltaic cells that convert sunlight into electricity. When the sun shines, it hits the cells and triggers electrons to escape their bonds. The electrons create a flow of electricity, which is switched to alternating current by your solar system’s inverter. From there, it’s used up by your appliances or sent back to the grid.

Solar is intermittent: It can’t produce electricity at night, when the sun isn’t shining or during cloudy weather. There are energy storage solutions to help offset this, but they’re expensive.

When choosing a solar company, you should compare prices as you would for any big-ticket item. Nerds recommend using a comparison tool like EnergySage, which compiles customer reviews, certifications and Better Business Bureau profiles to help you find reputable installers. You should also research solar companies’ warranty policies, because not all manufacturers and installers offer the same equipment quality or services.