You probably know why to buy a solar system. But do you know how?

While solar energy pays for itself and then some, it’s still too big an investment to make blindly. So here are some facts to help you make that investment wisely and safely – with an installation that performs as promised and gives you decades of trouble-free, dependable service.

Choose the type of system

More than 90% of U.S. solar installations are roof-mounted and tied to the power grid. Electricity they generate during daytime lowers your electric bills and sends excess power back to the utility company for credit. At night, you use power from the grid. If your roof isn’t pointed to produce enough solar energy, a ground mount system can be. Whether it’s for pumping water from a well or powering a small hunting cabin, a stand-alone off grid system lets you declare your independence from the power company. And adding battery backup storage to your system can keep the lights on and key appliances running as long as the sun keeps rising. (Milestone performs all these types of installations and has installed more battery backup systems within 200 miles of our offices than anyone else.)

Research the solar panels

Solar panels differ widely in quality, from high-output, world-class modules to outright pieces of junk. So go online, check the specs and particularly the reviews to be aware of what you’re getting. (Milestone installs modules made by REC, Europe’s leading brand and California’s number-one choice – and, for slightly more, Panasonic, arguably the world’s most powerful and efficient solar panels, with the world’s best warranty protection.)

Shop for value, not just price

Just one cheap cell in one cheap panel going bad can slash your whole system’s power output. Cutting costs with one cheap central inverter cuts your warranty protection by 60%. Cheap electricians without solar experience can make wiring mistakes that create fire hazards. Rooftop solar systems are supposed to last for 25 years or more. With cheap components and cheap, inexperienced and unskilled labor, they won’t.

Choose a certified installer

Installing a solar system safely and properly involves working with unusually high-voltage DC circuits and understanding things like temperature-corrected conductor selection, proper fusing and grounding, and proper string sizing. Most licensed electricians – even master electricians – without solar training and experience aren’t up to it. For an installer who is, look for NABCEP (North American Board of Certified Energy Practitioners) certification. Earning it calls for relevant real-world construction qualifications such as mechanical, structural and electrical engineering, as well as a track record of successful installations. (Five West Virginia solar installers have employees with NABCEP PV Installer certification. Milestone’s founder has earned two – for PV Installation and PV technical sales.)

Avoid site-unseen bids

No, that’s not a misspelling.

It takes more than reading a filled-out online form to know what kind of solar installation to recommend. So make sure that any installer you consider will make a free visit to your property to conduct a thorough site evaluation. (Milestone does.)

Compare multiple bids and ask multiple questions

Reading an installer’s bid can tell you not just how much the job will cost, but also how they’ll approach it. If there’s anything you don’t understand, ask – because the answer you get will also tell you a lot about how they work. If answers are evasive, or if they indicate the sales reps don’t understand specifics, that’s a red flag. Also, ask about the company’s business model. If they’re a high-volume outfit, for example, they may hurry the work to move on to the next job on time. If they’re smaller, they’ll take the time to make sure everything’s done right and take the time for extra quality steps, like flashing all roof penetrations to prevent damaging water leakage, at no added cost to you.

Check references

Ask the installer for names and contact information of customers with the type of installation you want. Then, make sure to talk to or visit them – preferably both.

Compare after-installation service

Will the installer come back 45 days after installation to make sure everything’s working as it should? What will they do if a problem develops later? (45 days after installing your solar array, Milestone follows up to make sure it’s performing every bit as well as promised. And in the unlikely event of a problem later on, we’re happy to answer questions and trouble-shoot on site.)

Compare the warranty protection

What’s important about a warranty is not just its terms, but also the health of the company that issued it. Down the road, if the company goes out of business, you’re out of luck. Some installers have bought up deeply discounted solar panels from dying companies, and your warranty protection could die with them. (Panasonic Solar’s warranty covers module workmanship and performance for 25 years. In addition, as West Virginia’s only Authorized Panasonic Solar Installer, only Milestone gives you an extended warranty, covering shipping and installation labor for 25 years.)