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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!

1020W
Frigidaire Gallery 22.2 Cu. Ft. Side-by-Side Refrigerator
60W
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!

1500W
Ceramic Space Heater
150W
Low-voltage 12V car heater
300Wh/d (2h * 150W)

Cooking

7000W
(3000W Range + 4000W Oven) Frigidaire Professional 30'' Electric
144W
Low-voltage 12V car cooker. Heats up to 300F – can cook rice, etc.
144Wh/d(1h * 144W)

Air Cooling

2425W
Frigidaire 25,000 BTU Room Air Conditioner
45W
Low-power Room Evaporative Cooler
405Wh/d (9h * 45W)

Transport

30,000Wh
Nissan Leaf (or equivalent combustion engine)
97Wh
Electric skateboard/ebike (though I prefer a bike to stay in shape).
97Wh/d (1 charge/d)

Communication

77Wh
Laptop, Tablet, Phone. Not really an issue. Already low power.
67Wh/d+10Wh/d (1 charge each/d)

Lighting

5W
LED Lighting (or 15W CFLs or 60W Incandescents)
5W
LED Lighting
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:



The kit

LED Light (45Wh – usable 9h/day)



Fridge (60W – usable 7h/day)



Stove/Water Heater Replacement (144W – usable 3h/day)



Heating Replacement (150W – usable 3h/day)



Air conditioning replacement (45W – usable 9h/day)



Transport replacement (97Wh – get 4 charges/day)



Communication (9W – usable 46h/day)

Note: Ad-blockers will block the Amazon links above, so here's the plain text links:
5W LED USB Lightbulbs (DC)
60W Mini-Fridge (DC)
144W Stove (DC)
150W Ceramic Space Heater (DC)
45W Evaporative Cooler (DC, but with AC brick)
97Wh Electric Skateboard (DC, but with AC brick)
9W Wifi (DC, but with AC brick)






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