Shade and Panel Layout: Why a Little Shade Costs a Lot

Shade is the biggest thief of solar output. Even a shadow from a vent pipe or power line can cut a panel's output a lot.

1. Why a small shadow matters

Panels are made of cells wired in series. Shade one cell and the current through that group drops. Bypass diodes let current skip the shaded section, but you still lose that part of the panel.

2. Strings

Panels in series share the same current. One shaded panel can pull down the whole string. Panels in parallel are less affected, but run at lower voltage.

3. Check your shade

• Look at the site at 9am, noon and 3pm, in winter if you can. Winter shadows are much longer.
• Trees grow. Plan for a few years from now.
• Watch for chimneys, vents, aerials, poles and neighbouring buildings.

4. Layout tips

• Keep shaded areas off the array if you can.
• Put panels with different shade on separate strings or separate MPPT inputs.
• Optimisers or microinverters can help on shaded grid-tie roofs. Ask your installer.

5. Quick summary

• Small shadows, big losses.
• Check winter shade.
• Group panels by shade and direction.

In Australia, any work on 240V AC wiring, including connecting an inverter, battery or solar system to a switchboard or fixed wiring, must be done by a licensed electrician.

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