Solar 101: How to evaluate solar contractors for rooftop projects


From pv magazine International

The first articles in our Solar 101 series, (Is my roof ready for solar?) and (Attaching your solar system to your roof) examined how the age and physical characteristics of a roof affect the design and payback of a prospective solar system. We also discussed the design constraints resulting from wind, dirt, and precipitation. And, in Working the angles to maximize your solar system’s output, we looked at the relationship between a panel’s latitude, pitch and azimuth to its solar electricity output.

Now, we’ll look at how to find a solid solar contractor to build your solar power system.

A well-designed solar system should last 20 or 30 years, or longer. The mounting hardware, which attaches directly to your home, will typically require drilling holes in your roof. But don’t fear. This guide for choosing the right contractor should help ease your concerns.

Experience counts

One rule of thumb: Find someone experienced. Installing solar panels, like anything else, involves doing a set of similar actions over and over. Experience represents more than just the labor of attaching solar panels and the required electrical gear. For instance, experience usually indicates:

  • Better pricing from hardware distributors
  • Knowledge of local permit and utility requirements
  • Solar hardware expertise, optimized hardware to meet customer needs.

Recent research by the U.S. Department of Energy’s Berkeley Lab suggests that more experienced contractors offer better pricing.  This chart from their annual Tracking the Sun report doesn’t explicitly break down experience, but it does show how pricing can vary by contractor.

Experienced solar contractors have a truck filled with various odds and ends leftover from prior solar jobs. These little components often mean the difference between finishing a project in a day or two, versus two or three days with several trips to the local hardware store mixed in.

The question then becomes “how do we find an experienced solar contractor?”

Local connections

First off, ask your friends. And as strange as it may sound, knock on the door of someone who has already installed solar power and ask them. These folks have real experience with a contractor, and can give you a tip or two as you ask questions of prospective contractors.

If you know contractors who have done good work for you already, ask them who they would hire to install a solar system on their roof. Roofing and electrical contractors often have pre-existing relationships with solar contractors because their businesses have a lot of overlap. Your HVAC contractor may also have a good working relationship with a solar contractor. And finally, local professional engineers (specifically structural and electrical) will have knowledge of the local solar contractors because they have to sign off on solar design drawings.

Another technique is to reach out to your local town hall to learn who the local permit office likes to deal with. Be sure to ask which solar contractors always seem to submit the right paperwork. This question may be more important than it appears, because paperwork is a huge part of a solar installation.

And one last technique: Call your local contractor supply houses. Again, the supply houses have relationships with contractors that buy the most hardware from them. For this call, come prepared with a few key questions: Who pays their bills on time, who’s been in business the longest, and who is most organized?

Cold calling

One way to vet a contractor is to simply call them and see how they follow up with you. Their follow-up will give you an idea about the quality of service you might receive later in the process.  Be sure to call an actual local contractor, and not a sales organization that will simply hand the lead off to a contractor.

A few items to consider when the contractor representative shows up:

  • Is the person who arrives at your door deeply knowledgeable, or just a sales rep plowing through leads?  This can be tough for a lay person to determine. Do some research and be ready with  some technical “gotcha” questions. Also, talk to the rep casually, and try to find out a bit about their company.
  • Try to get ballpark price estimates before the representative visits. Compare these rough local prices to the quote you’re given. Sales organizations typically add a chunk of money on top of whatever the contractor charges. And be warned: Some contractors will charge you based on how much your house appears to cost, irrespective of the system’s cost.

After reaching out to locals and others in the know, the next place to go is Google. But beware: Companies – and especially sales organizations – specialize in placing themselves high up the Google search results.

Contractors, on the other hand, specialize in building things. Many good builders lack grammar and/or web development skills. Look the other way and evaluate them on attributes that matter: reliability, knowledge, experience, and work product.

The one place that this author regularly sends people is SolarPowerWorldOnline’s Top 500 list. You’ve got to be smart, however, about using this list.

First, make sure you choose your own state because the default list is national. Second, recognize that companies pay a fee to get on the list. And third, consider that the companies near the top of the list are likely the largest national companies.

Second path

A second path to follow without cold calling is to use EnergySage. Contractors submit their profile to the company, must have at least 10 installations with positive reviews, and are regularly re-vetted.

Here’s the key value kicker from EnergySage: After you submit your address, you will get a few quotes from contractors who  know very well that they are competing with at least two or three other contractors. This will likely force these contractors to work their numbers to be competitive.

Contractors pay commissions to EnergySage – about $1,000 if the customer ends up installing. However, that commission is comparable to what a door-to-door salesperson might make.

Of course, you should also consider the largest national companies, with Sunrun, Sunnova, and Tesla being the big three these days. These companies all have unique offerings, and also some similar products, so research each of them and their offerings to know which might best fit your needs.

Sunrun and Sunnova are best known for their solar lease products. In essence, you rent your rooftop to them in exchange for a “free” solar power system. Tesla’s main business is to sell you a system that you fully own, whether it be standard solar panels or their new Solar Glass roof product. Both Sunrun and Sunnova will also sell, but their system costs typically don’t compete with Tesla’s pricing model.

The compromise: You will likely get the cheapest price for residential solar hardware from Tesla, but there also will probably be less personal interaction and system optimization.

A small local company might not be able to provide the lowest hardware prices, but will likely put more effort into customizing a design to fit your specific application. And always keep one eye open. Some mid-sized companies will quote twice as much as their competitors.

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