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603 Solar customers describe help with the whole solar project, from explaining system options to getting panels connected and running. The company says it designs and installs residential and commercial solar systems from Exeter, serving New Hampshire, southern Maine and northern Massachusetts. It names Zachary Haithcock and Sean Carlson as co-founders and says it has helped nearly 1,000 home and business owners switch to solar since 2018. Battery storage, EV chargers and generators are also advertised. Recent customers describe communication before and after installation. A June 2026 reviewer said Sean explained the process, answered calls and kept in touch; the installers cleaned up, and the system was working as expected. Another June customer praised fast communication and support through the post-installation stage. In May 2026, a customer said Emma and Steve explained owning versus leasing panels without pressure, followed by a smooth installation. Service extends to existing systems. A May 2026 customer said their original installer had gone out of business and their system had stopped working; 603 Solar serviced it and got it running again. An April 2026 reviewer said their panels had been producing for more than two years, exceeded projected production during the first year and came with quick help when questions arose. These are customer reports of individual systems. Roof layout and installation partners feature in older accounts. In a February 2026 review, a customer described a 16-panel array on a challenging roofline, said 603 Solar’s price was the lowest of three quotes and credited Grateful Electric with the installation. A May 2024 reviewer described panels on a stand-alone barn roof in Madison, underground conduit to the house and heavier power cables to allow future expansion. That customer said 603 Solar handled the electrical permit and coordinated the grid connection. A July 2024 Reddit commenter called the company reputable and its estimates accurate, but raised concern that it subcontracted all the work and had not been around long. That was the commenter’s assessment at the time. Other Reddit commenters recommended 603 Solar in 2022 and January 2025, including for the Seacoast area. Google reports a 5-star average from 170 ratings. BBB gives the company an A+ grade. Its New Hampshire electrical licence is active.
“603 Solar is a good bet”
“603 Solar in Exeter is a solid option. Locally owned (unlike GSS).”
“I've seen 603Solar around, too.”
“603 is a reputable company and seem to have accurate estimates. The biggest issue I see with them is they subcontract all the work, and they haven’t been around long.”
“603 Solar and Revision Energy would be my top solar recommendations for the area.”
“Hedderly is with 603 Electric, an install partner with 603 Solar, the contractor on the project.”
“Zach Haithcock, co-founder of 603 Solar, shows the breaker box for the new solar array to Dublin Energy Committee Chair James Finnegan.”
603 Solar is been amazing. They are professional, timely, and great communicators. We were blown away by how seamless and easy the whole process was.
STOP - See alert below!!! If you are checking reviews before buying a solar system you have found the right company. 603 Solar is: - Professional - Knowledgeable - Flexible - Zach delivers on his promises and no BS. ... Just like it used to be in the old days. 603 Solar has just installed a high quality system for us using high quality components. UPDATE During the first month, the system produced 3.6 MWh which if billed by Central Maine Power would cost between $880 to $970. In other words it equals a paycheck of approx $1,500 that I would have to earn BEFORE TAXES, ALERT Be on extreme alert if you are talking to "installers" or sales people from companies that are more interested in having you sign a contract than discussing the system. They may offer you a 30% rebate with some convoluted contract or lease agreement. CAUTION. The fine print is NOT presented up front. But it turns out that you only gain a few PERCENT (not 30%), and what happens if you end the lease early? Penalties? Bottom line - BS A solar installer should offer installations not convoluted attorney arrangements. Did this alert help you?
Outstanding Experience I had an amazing experience with 603 Solar. Everything was on time, communication was fast, and the support was excellent from the very first visit through post‑installation. The whole process was smooth, professional, and absolutely flawless. I highly recommend 603 Solar to anyone considering going solar.
Sean did a wonderful job of explaining everything from start to finish. He has always answered the when we called. He is constant communications with us throughout the process. I have personally done an unexpected visit to the office and gotten a walk-through of the facility. CUSTOMER SERVICE IS OUT OF THIS WORLD. The installers worked great and they cleaned up behind themselves. System is working as it should.
603 Solar are pros and make it easy. They know their stuff and use the best equipment on the market! The whole process was simple and easy and saves us tons of money in the long run!
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2 changes recorded — last scanned Sep 30, 2026.
