A Massachusetts homeowner turned to social media after being confused by two different system sizes on the same $49,000 solar panel proposal: 17.6 kilowatts DC and 15.1 kilowatts AC.
Here's what to know
The homeowner took their questions to Reddit's r/Solar forum, where they asked, "Should I be calculating cost per DC or AC kw? This would be a 40 panel roof installed project in Massachusetts
In the Reddit thread, the original poster was seeking "quote feedback" on their $49,000 estimate for a system with a 17.6-kW DC size, a 15.085-kW CEC-AC rating, 40 JAM54D41 MB panels, and 40 IQ8MC-72-M-US [240V] inverters.
Solar panels generate DC electricity, and the inverters convert it to AC for home use.
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People replying to the thread clarified that the price-per-watt calculation should use the DC system size. Based on 17.6 kW, the proposal comes out to about $2.78 per watt, which is much more favorable than using the lower AC rating.
One comment wrote, "for system pricing, you look at installed kWdc, so panel wattage x quantity." Another user similarly added, "DC is what you paid for so that's the number to use, works out around $2.78/watt, which is decent for MA."
What can be done?
For comparing solar bids, the 17.6-kW DC figure offers a more consistent benchmark, while the installer's annual production estimate provides a better idea of what the $49,000 system might actually produce on a Massachusetts roof.
As the discussion shows, going solar is one of the best ways to save money on home energy, and homeowners comparing bids can use EnergySage to get free solar installation estimates and compare quotes. With EnergySage's help, the average person can save up to $10,000 on solar purchases and installations.
EnergySage's solar map shows the average cost of a home solar panel system by state, along with details on solar panel incentives for each state.
Plus, adding battery storage to a solar setup is one of the best ways to protect your home during outages, save money on energy, and go off-grid. For a 40-panel setup like the one in the Reddit post, homeowners can explore EnergySage for information about home battery storage options, including competitive installation estimates.
Where can I learn more?
These stories take a closer look at the costs, savings, and incentives that can shape a solar quote like this one.
• Energy experts helped 60,000 homeowners slash prices by $9,000 on rooftop solar installations.
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