Introduction
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Electricity
The flow of sunlight is measured in Watts and can be thought of as raindrops, measured in the following way:
| Unit | Example of usage | Analogy | Analagy example of usage | |
|---|---|---|---|---|
| 1 Watt (W) | 1 LED night light | one raindrop per second | a light drizzle of rain | |
| 1 Kilowatt (kW) | a microwave | 1,000 raindrops per second | a downpour of torrential rain | |
| 1 Kilowatt-Hour (kWh) | electric oven for 24 min | the total amount of raindrops collected in one hour | the amount of water in a jacuzzi hot tub | |
| 5 Kilowatt-Hour (kWh) | electric oven for 2 hrs | the total amount of raindrops collected in five hours | the amount of water in a swimming pool |
Common electric usage
The amount of electricity you use will vary throughout the day, depending on which items you use and for how long.
For comparison, the following table lists the actual kW and kWh we use.
| Electric item | Size | Remarks | kW usage | Annual kWh |
|---|---|---|---|---|
| Microwave oven | 2.2 cu.ft. | 5-10 min/day | 1.5 - 1.8 | 25 - 50 |
| Dishwasher | 24" x 24" x 35" | 1 kWh per 60 min cycle | 0.6 - 2.5 | 48 - 60 |
| Clothes washer | 27" x __" x __" | 1-2 kWh per 30 min load | 1.2 - 3.0 | 96 - 108 |
| Clothes dryer | 27" x __" x __" | 2-5 kWh per 60 min load | 2.0 - 6.2 | 312 - 360 |
| Oven | 5.0 cu.ft. | 300 - 425 °F | 5.0 - 9.6 | 850 - 950 |
| Heat pump + AC | 1.5 tons | 68 °F | 0.5 - 1.5 | 1100 - 1500 |
| Water heater | 40 gallon | 30 amp, 120 v, 1 hr/day | 0 - 4.5 | 1600 - 1700 |
| EV wall charger | 32 amp | 40 amp breaker | 1.0 - 7.7 | 400 - 2000 |
| Stove | 5 elements | 2 kWh x 3 hrs/day | 1.2 - 3.0 | 2000 - 2200 |
| Refrigerator | 27 cu.ft. | runs 24/7 | 0.5 - 1.1 | 1450 - 2900 |
| =========== | ||||
| 6400 - 8300 |
Once, for an hour, we were washing and drying a load of laundry while using the oven and stove--all at the same time. That "maximum usage" of 11.5 kW turned out to be good to know since our Powerwall+ is able to supply a maximum output of 5.7 kW, which required the remaining 5.8 kW to come from the Grid.
So, we learned to use heavy appliances at different times--until we added a second Powerwall. (That issue is no longer a problem since a Powerwall 3 can output 11.5 kW)
Luxury electrical usage
| Electric item | Size | Remarks | kW usage | Annual kWh |
|---|---|---|---|---|
| Space heater | ||||
| Heat pump water heater | ||||
| Jacuzzi | ||||
| Steam room |
30-year comparison
See the Google Sheet that details the enormous savings that comes from converting to electric:
