What to know before you read a quote
Two things decide what a solar array is worth: where it sits and what is on the datasheet. These guides cover one each - how to get a defensible production figure for a specific roof, and how to read the specification sheet the installer attached to the quote.
Neither is a sales page. They explain the arithmetic well enough that you can check somebody else's, which is the only useful kind of guide.
The guides
Where the data comes from
Every specification on the site is read from a manufacturer datasheet. Nothing is modelled or estimated, and a panel that does not publish a figure is left out of the average rather than filled in.
Browse the catalogueOne page per brand, computed from that brand's own modules: what they build, at what efficiency, on what cell architecture and under what warranty.
All manufacturersTwo residential systems are covered in the same detail: usable capacity, continuous power, round-trip efficiency and what inverter each one needs.
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