← Energy H61-02 · Module 2 of 7 · Pages: 22 · Worksheets: 6

Solar panels

How much electricity panels give at your latitude, how to choose the site, tilt and size, from a small henhouse kit to a whole-house system

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Solar panels

In short

  • 1 kWp of panels gives roughly 850–1,100 kWh a year in the UK and Ireland and 1,200–1,700 kWh in most of the US.
  • In December the same panel gives roughly 5–8 times less than in July at UK latitudes (about 2 times less in the southern US).
  • Best is south-facing, tilt 35–40° (30–35° in the southern US); for winter in an off-grid system 60–65°.
  • Shade on part of one panel drags down the output of the whole string. Check shade in December.
  • A panel in daylight always produces voltage. A string has hundreds of volts DC: connection is done by a qualified electrician.

What's inside

Chapters

  1. What the panel label says
  2. How much electricity the sun gives
  3. Site, orientation and tilt
  4. Roof, ground or carport
  5. Small 12 V systems for the homestead
  6. A house system: grid-tied, hybrid or off-grid
  7. How many panels and how to connect them
  8. Buying and installing
  9. Maintenance through the year
  10. Common mistakes
  11. Printable checklist

Worksheets

  • Panel size and string voltage
  • Monthly production
  • Comparing quotes
  • Roof sketch and shade check
  • Production log
  • Solar panel calendar

Fields and checkboxes can be filled in with Adobe Acrobat Reader (desktop and mobile), and the calculator adds up by itself. Filling in may not work in some browsers. A print version comes with the screen PDF.

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