Low-Power Device Guide
A lot of questions we receive here are as to what you can charge and how far the energy will reach. I thought this would be worth a separate, more in-depth analysis.
What adjustments would living off a single 420Wh system require of your lifestyle? Worst energy culprits in my household are roughly in order of energy use: hot water tank for showers, stove/kettle, transportation, air heating, air cooling, fridge, dishwasher, washer/dryer, lighting. Living off 420wh a day requires replacing the culprits with lower-power parts (often intended for car, RV or marine use). At this point this project becomes very similar to the original inspiration for these projects - Robin Rhineharts How I gave up alternating current (Robin Rhinehart is the founder of Soylent). Replacing high-energy AC appliances with low-energy DC ones to stay within the 420Wh “budget”.
Low-power thought experiment: How could we replace devices to live within the 420Wh solar personal power plant budget?
Refrigeration A large part of the baseload in apartments and houses is from the fridge. Obviously essential for a modern lifestyle (unless you order take-out a lot or live off powder), it’s the main power draw we can’t live without. That being said, existing fridges are often super in-efficient. Let’s replace it with a low-voltage car fridge!
Frigidaire Gallery 22.2 Cu. Ft. Side-by-Side Refrigerator
Low-voltage 12V car fridge (smaller size), no freezer.
420Wh/d (60W * 7h)
Heat The next-biggest baseload (at least in winter) is from heating. This is often oil-based, but (at least in San Francisco where old houses are terribly insulated) is often assisted with electric space-heaters. These are also incredibly in-efficient (as they’re often bargain-basement appliances). Let’s again replace with low-voltage car heaters!
Ceramic Space Heater
Low-voltage 12V car heater
300Wh/d (2h * 150W)
(3000W Range + 4000W Oven) Frigidaire Professional 30'' Electric
Low-voltage 12V car cooker. Heats up to 300F – can cook rice, etc.
144Wh/d(1h * 144W)
Frigidaire 25,000 BTU Room Air Conditioner
Low-power Room Evaporative Cooler
405Wh/d (9h * 45W)
Nissan Leaf (or equivalent combustion engine)
Electric skateboard/ebike (though I prefer a bike to stay in shape).
97Wh/d (1 charge/d)
Laptop, Tablet, Phone. Not really an issue. Already low power.
67Wh/d+10Wh/d (1 charge each/d)
LED Lighting (or 15W CFLs or 60W Incandescents)
40Wh/d (2 lights * 4W * 5h)
Total energy required to use all devices above every day:
1483Wh/day, roughly 1.5kWh
This can be covered by 4 systems/personal power plants for roughly $880 dollars. Granted, we’d raise some eyebrows, but we wouldn’t be living like a hermit and it’d be as close as we could get to an off-grid DC-only lifestyle.
See all the devices listed above below. Note that all of them (apart from the evap cooler) run on DC, so you could theoretically leave off the AC inverter and run directly off 12V DC (shoot me an email if you have any questions).
High-power devices in my household that have no low-power replacement yet:
- Hot water tank: 4200W water heater => would have to be replaced with a solar water heater. This is a non-electric, purely mechanical system, similar to the system installed by Jimmy Carter on the white house in the 70s.
- Dishwasher: Dishwasher => Hand wash dishes. Sorry y’all.
- Washer/dryer: Washer/Dryer => Hand wash clothes and hang dry feasible?