Run This Appliance
Can a Solar Generator Run a Space Heater?
Yes, for about 34 minutes on a 1,000Wh unit. Here is why physics makes this the worst thing you can ask a battery to do.
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What's in this article
The runtimes, exactly
| Battery | 1,500W (high) | 750W (low) |
|---|---|---|
| 500Wh | ~17 min | ~34 min |
| 1,000Wh | ~34 min | ~68 min |
| 2,000Wh | ~68 min | ~2 hr 15 min |
| 4,000Wh | ~2 hr 15 min | ~4 hr 30 min |
Allowing for the ~15% inverter loss you always pay.
| Appliance | EcoFlow DELTA 21,024 Wh | Bluetti AC200L2,048 Wh | EcoFlow DELTA Pro 34,096 Wh |
|---|---|---|---|
| Space heater (1500W)~1500W running | 35 min | 1.2 hr | 2.3 hr |
| Gas furnace blower~400W running, cycles ~40% of the time | 5.4 hr | 11 hr | 22 hr |
| Box fan~75W running | 12 hr | 23 hr | 46 hr |
| Full-size refrigerator~150W running, cycles ~35% of the time | 17 hr | 33 hr | 66 hr |
Look at the space heater row against the furnace blower row. Same batteries. One approach works and one doesn't.
Why physics is against you here
Most appliances do something clever with electricity — a fridge moves heat rather than making it, which is why a 150W compressor can cool a whole box.
A resistive heater has no such trick. Every watt in becomes a watt of heat out. That's actually 100% efficient, which sounds good, and is exactly the problem: there is no headroom to optimise.
What to do instead
If you have gas or propane heat — this is the big one
You only need to power the furnace blower.
The burner doesn't need electricity. Only the fan that pushes warm air through the ducts does — around 400 watts, cycling maybe 40% of the time. verify
A 1,000Wh unit carries that for hours, and it heats your entire house instead of one corner of one room.
That is the single best use of backup power in cold country, and almost nobody knows it.
The catch: a furnace is hardwired. You can't plug it into a battery. It needs a transfer switch or an interlock kit fitted by a licensed electrician. Never improvise it, and never backfeed through a wall outlet.
If your heat is electric
Be straight with yourself: a portable battery is not a heating solution and no amount of shopping changes that.
What actually works:
One room. Close every other door. A blanket over the doorway if you're serious.
Layers, sleeping bags, hats. Unglamorous, extremely effective.
Everyone sleeping in the same room. Bodies are 100-watt heaters that need no charging.
Know where the warming shelter is. In a multi-day outage with electric heat, leaving is a legitimate plan, not a failure.
The one case where it makes sense
Short bursts. Take the chill off a bedroom for 20 minutes before bed, then switch off and get under the covers.
That's a genuinely good use of 500Wh. It's just not the same thing as "running a space heater."
The short version
It runs. It doesn't last.
If you're cold and you have gas heat, spend the money on getting your furnace blower onto a transfer switch. If your heat is electric, spend it on sleeping bags — and don't let anyone sell you a battery on the promise that it'll keep the house warm.
The picks, in detail
Specs come from data/products.json, so they're the same everywhere on this site.
EcoFlow
EcoFlow DELTA 2
The one most people should buy. It refills fast enough that a short sunny break between storm bands actually matters.
- Capacity
- 1,024 Wh
- AC output
- 1,800W
- Weight
- 27 lb
What's good
- Wall recharge is genuinely quick — useful when power flickers back for an hour
- LiFePO4 cells, so it tolerates being left plugged in for years
- Six AC outlets means no daisy-chained power strips on the kitchen counter
- Add an extra battery later instead of buying a whole second unit
What's annoying
- The fan is audible in a quiet bedroom at night
- 1800W ceiling rules out most space heaters and hair dryers
- Expansion batteries cost nearly as much as the unit itself
Who this is wrong for
Anyone who needs to power a well pump, an electric water heater or a central AC. It will not start them, and it is not a whole-home unit.
Bluetti
Bluetti AC200L
Specs unverifiedA lot of battery for the money, with the port selection of a small workshop.
- Capacity
- 2,048 Wh
- AC output
- 2,400W
- Weight
- 61.9 lb
What's good
- Expandable, unlike most Bluetti units at this size
- A genuinely useful spread of ports including a 30A RV outlet
- Fast recharge for a 2kWh unit
What's annoying
- Shorter warranty than EcoFlow and Jackery offer
- Big and awkward to store
- Bluetti's US service turnaround has been inconsistent
Who this is wrong for
Small apartments. It's physically large and you will trip over it.
EcoFlow
EcoFlow DELTA Pro 3
Specs unverifiedThe first portable unit that can honestly claim to back up parts of a house, including 240V circuits.
- Capacity
- 4,096 Wh
- AC output
- 4,000W
- Weight
- 113 lb
What's good
- 240V output covers well pumps and some dryers, which almost nothing else portable does
- Pairs with a transfer switch so you stop running extension cords through a window
- Chains with extra batteries into genuinely serious capacity
What's annoying
- Costs about the same as a permanently installed standby generator once you add a transfer switch
- 113 lb means it lives where you put it
- The install to make it useful is an electrician job, not a weekend project
Who this is wrong for
Anyone who wants to move it more than once. It has wheels for a reason, and stairs will beat you.
Questions people actually ask
Can a solar generator run a space heater?
What size battery do I need to run a space heater all night?
Does using the low setting help?
What is the alternative if I have gas heat?
What if my heat is electric?
Who wrote this
GreenCommuteGuide Editorial Team
Research and fact-checking
We research backup power the boring way: manufacturer spec sheets, UL and FCC filings, warranty documents, and the complaints buried on page four of the reviews. When we haven't tested something ourselves, we say so on the page instead of pretending.
- · Every spec on this site is checked against the manufacturer's current published documentation before publication
- · We do not accept payment for a rating, a ranking, or a positive verdict
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