How many solar panels does a pool pump need?
A variable-speed pool pump uses about 4 kWh a day while the pool is open. The season length decides the rest. In a typical city that is about 1 extra panels (0.4 kW), or $1,000–$1,500 added to the system price.
| City | Extra kWh a year | Extra kW | Extra panels | Added cost |
|---|---|---|---|---|
| Seattle, WA | 0 | 0.0 | 0 | $0 |
| Portland, OR | 240 | 0.2 | 1 | $600 |
| San Francisco, CA | 0 | 0.0 | 0 | $0 |
| Los Angeles, CA | 600 | 0.4 | 1 | $1,100 |
| Phoenix, AZ | 840 | 0.5 | 2 | $1,400 |
| Las Vegas, NV | 600 | 0.3 | 1 | $1,000 |
| Denver, CO | 240 | 0.1 | 1 | $400 |
| Salt Lake City, UT | 360 | 0.2 | 1 | $700 |
| Dallas, TX | 840 | 0.6 | 2 | $1,700 |
| Houston, TX | 840 | 0.6 | 2 | $1,800 |
| Minneapolis, MN | 360 | 0.3 | 1 | $800 |
| Chicago, IL | 480 | 0.4 | 1 | $1,100 |
| Detroit, MI | 480 | 0.4 | 1 | $1,200 |
| Atlanta, GA | 600 | 0.4 | 2 | $1,300 |
| Miami, FL | 1,440 | 1.0 | 3 | $2,900 |
| Charlotte, NC | 600 | 0.4 | 2 | $1,300 |
| Washington, DC | 480 | 0.4 | 1 | $1,100 |
| New York, NY | 480 | 0.4 | 1 | $1,100 |
| Boston, MA | 360 | 0.3 | 1 | $800 |
Assumes 0 months with average temperatures of 18 °C or more, 4 kWh a day. South-facing roof, $3.00/W. Rough planning figures.
What the table doesn't show
A variable-speed pump uses a third to a half of the energy of an old single-speed pump. Replacing the pump often saves more than adding panels.
Pool pumps run in the day, when panels produce, so almost all of the extra solar is used directly: the best case under net billing.
Also: How many solar panels does an electric car need? · How much solar does a heat pump need?