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Choose panels

In Panels, pick a panel from the list or search every panel on the California Energy Commission list. Each card shows the power, size, area, efficiency and type; the panel is shared with the roof editor.

The panel sets how much power each spot on the roof makes and how many panels fit, so it’s worth choosing before you lay out the roof.

Pick a panel

  1. Open Panels

    In the calculator, open Panels. The list shows common panels; Cali-Graf default marks the default one.

  2. Search if it’s not there

    Type in Search all CEC modules — a brand and a wattage are enough, like “REC 405”. The search covers every panel on the California Energy Commission list.

  3. Choose it

    Click the panel. Rows and Cards switch how the list looks. The info button on a card opens all its specs — see Equipment details: specs, temperature, warranty.

What the card shows

Power

Rated power at standard test conditions (STC), in watts — the number in the panel’s name.

Size and area

Length × width, used to lay out the roof.

Efficiency

How much of the sunlight on its area the panel turns into power at STC. Higher efficiency fits more watts on the same roof.

Type

The cell technology; “Bifacial” panels also use light reflected onto their back side.

STC is a lab test. Power at PTC in the panel’s details is closer to what a panel makes outdoors — the calculation models real conditions hour by hour anyway.

Shared with the roof editor

The panel is the same in the roof editor — changing it here changes the design. A panel of another size after the roof is laid out needs a new layout — see Change the panel after the roof is laid out.

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