Every off-grid sizing conversation starts with the same spreadsheet: list your appliances, multiply watts by hours, add it up, see if the total fits under a solar array. That math gets your daily kilowatt-hours roughly right — and it can still hand you a system that trips, sags, or quietly runs a generator every week.
The number that actually decides whether a house can leave the grid isn’t the daily total. It’s the worst half-second of the day, when the well pump kicks on the instant the fridge compressor restarts and the mini-split’s outdoor unit happens to be ramping up. That collision — not your average consumption — is what sizes the inverter, and the inverter is what decides whether “off-grid” is a real plan or a number an installer is happy to sell you anyway.
What follows is a load-by-load walk through the appliances that actually make or break an off-grid budget — well pump, mini-split, electric range, clothes dryer, EV charger, fridge and freezer — with real numbers for what each one draws, what it surges to, and whether it’s realistic on batteries alone or wants a propane (LPG) backup. Run your own list through the same math afterward in the load calculator — it takes about five minutes.
The Question Has the Wrong Shape
“Can my house run off-grid” isn’t a single yes/no number, because a load isn’t one thing — it’s three. There’s the continuous average draw, measured in kilowatt-hours per day, which sizes the battery bank and solar array. There’s the starting surge, measured in kilowatts for a second or two, which sizes the inverter. And there’s how much you’re actually willing to change — swap an appliance, shift when it runs, or accept a propane tank for the loads that don’t make sense on batteries. Most sizing mistakes come from answering only the first question.
- Is it continuous or cyclical? A compressor’s nameplate wattage is what it draws while running, not what it averages over a day of cycling on and off — that gap is where naive load lists overestimate everything with a motor in it.
- Does it have a motor that starts under load? That’s the surge — often three to six times the running watts for a second or two, and it stacks with whatever else happens to start at the same moment.
- Can it be scheduled? A load you control the timing of — an EV charger, a dishwasher — is nearly free to run straight off solar. A load that has to run whenever you want it — lights, the fridge — has to come out of the battery.
Walking the House, Load by Load
Here’s how six of the biggest household draws actually behave — not their sticker wattage, but what they cost over a real day and what they do to an inverter for the second they start.
| Load | Running watts | Starting surge | Typical daily use | Off-grid verdict |
|---|---|---|---|---|
| Fridge / freezer | 100–200 W | 800–1,200 W, ~1 sec | Cycles ~30% of the day · 1.5–2.5 kWh | Easy — stays on the inverter full-time, barely moves the needle |
| Well pump (0.5–1 hp submersible) | 750–1,500 W | 2,500–6,000 W, 1–3 sec | 20–40 min cumulative · 1–3 kWh | Easy on kWh — the surge is the trap; check inverter headroom |
| Mini-split heat pump (12k–24k BTU) | 500–2,000 W, rises as it gets colder | Near-zero — inverter-driven compressors soft-start | 4–15 kWh, climate-dependent | The real budget item; easy in mild climates, needs backup in hard freezes |
| Electric range + oven | 2,000–5,000 W burners · 2,000–3,000 W oven | None — resistance heat, no motor | 1–3 kWh (short cycles) | Low energy, high instant draw — most off-grid homes go propane here |
| Electric clothes dryer | ~5,000 W | None | 4–5 kWh per 45–60 min load | Worst kWh-per-minute appliance in the house — propane, heat-pump, or a line |
| EV charger (7–11.5 kW wallbox) | 7,000–11,500 W for hours | None — electronic, no motor | 6–12 kWh for an average commute | Easier than it looks — no surge, and fully schedulable to sun hours |
The Surge Nobody Budgets For
Watts times hours sizes the battery. The moment two or three motors decide to start at once is a different problem entirely, and it’s the one naive load lists miss completely:
One pump starting alone
A well pump’s locked-rotor surge alone might hit 4,000 W for a second or two — comfortably inside most whole-home inverters’ surge rating.
Pump, fridge and mini-split at once
Let the pump start the instant the fridge compressor restarts and the mini-split ramps up, and the same house can touch 7,000–8,000 W — on a system averaging barely 1 kW.
A whole-home off-grid inverter carries two ratings for exactly this reason: a continuous rating — often 8–15 kW for a family home — and a surge rating, usually 1.5–2× continuous, holding for only a few seconds. Undersize it and the symptom isn’t a dead battery — it’s breakers, or the inverter itself, tripping every time two big loads land on each other, which is exactly the arithmetic the load calculator runs for every appliance entered.
The Dryer Is the Real Off-Grid Tax
A standard electric clothes dryer is a five-kilowatt resistance heater with a drum attached, and it runs flat-out for 45 minutes to an hour. That’s four to five kilowatt-hours in one load — more energy than an efficient fridge and freezer combined use in a day and a half. It’s the single worst kilowatt-hour-per-minute appliance in a typical house, which is exactly why most real off-grid homes don’t run one. The usual fixes: a propane dryer (most off-grid houses already have a tank for the range or water heater, so adding the dryer is nearly free), a heat-pump dryer (slower, pricier up front, but sips 1.5–2.5 kWh a load instead of 5), or the oldest fix there is — a clothesline, which is free on every day it isn’t raining.
Key number
Move just the clothes dryer off the battery bank — propane, heat pump, or a line — and a typical whole-house off-grid battery bank shrinks by roughly a third. One appliance choice moves the sizing more than almost anything else on the list.
EV Charging Is Easier Than It Looks
A home EV charger — “Level 2” in US terminology, just a wallbox in Europe — pulls more raw power than almost anything else in the house: 7 to 11.5 kW for hours at a stretch, six to twelve kilowatt-hours for an average commute. On a naive load list that looks terrifying. In practice it’s one of the friendliest loads you can add, for two reasons. There’s no motor, so there’s no surge — it’s pure electronics pulling a flat, predictable number. And it’s the most schedulable load in the house: set it to run only from late morning to mid-afternoon and it draws straight off the array while the sun’s up, instead of off the battery at 2 a.m. A load timed to the solar window barely touches battery sizing at all; a load that can’t be — the fridge, the lights — has to be covered by it around the clock.
So, Can You? Three Honest Verdicts
Put the loads together and a real house sorts into one of three tiers. None of them are about whether the physics works — solar and batteries will run a resistance dryer if you buy enough of them. They’re about whether the system still makes financial sense.
Tier 1 — Fully Electric, No Propane
An efficient, mild-climate home with heat-pump everything (space heat, water heat, dryer) and EV charging timed to midday typically lands around 30–45 kWh a day. That calls for roughly a 10–14 kW solar array and a 30–40 kWh battery bank to ride out a couple of cloudy days back to back — realistically $45,000–$65,000 installed in the US, or somewhere near €40,000–€60,000 in Europe. Fully electric off-grid is genuinely realistic here. It’s just not cheap.
Tier 2 — Electric, With One or Two Loads Shifted
Move the range and dryer to propane and keep a small backup generator for the worst week of winter, and the same house’s electric load drops to 15–25 kWh a day — roughly a 6–9 kW array and 15–20 kWh of battery, often close to half the Tier 1 price either way. It’s arguably more reliable too: the generator, or the propane tank, is the answer on the one week a year the sun doesn’t show. This is where most real off-grid homes land.
Tier 3 — Not Economically Off-Grid, Yet
Whole-home electric-resistance heat — baseboards, an electric furnace, an electric tank water heater — in a cold climate can push a house to 80–150 kWh a day in January, exactly when solar generation is at its yearly low. Covering that on batteries means sizing for a small commercial building, not a house. The physics still works; the economics stop making sense long before the spreadsheet is finished. The honest fix isn’t a bigger battery, it’s swapping the heat source — a heat pump or a wood stove — before spending a dollar on solar.
US Split-Phase vs European 230V: Same Method, Different Numbers
The load-by-load method above doesn’t change by country; the numbers going into it do. In the US, well pumps, ranges, dryers and EV chargers are usually wired 240V split-phase, and most whole-home off-grid inverters are built around that — natively, or by stacking two units. In Europe, homes run 230V single phase, though many rural properties — anywhere there’s a well, a workshop, or an older farmhouse — carry 400V three-phase instead, so the harder sizing question is often three-phase compatibility rather than surge stacking. The appliance mix differs too: gas hobs are still the European default, tumble dryers sold there lean heat-pump rather than resistance, and a private well pump is the exception outside agricultural properties. Same three questions from the top of this piece, just answered with a different voltage and a different starting appliance list.
Off-Grid Load Questions, Answered
What’s the single biggest load in a whole-house off-grid system?
Averaged over a year, it’s usually space heating and cooling — a mini-split can swing from a few kWh a day in shoulder seasons to 15-plus on the coldest days. Per single cycle, though, nothing beats a clothes dryer or a full range-plus-oven for instantaneous demand.
Do off-grid homes still need a backup generator?
Most real ones keep one. Even a generously sized system runs into three to five genuinely bad-sun days a year, and a small backup generator for those days is cheaper than the extra solar and battery needed to never require it — nearly a rounding error if there’s already a propane tank on site.
Can a mini-split heat pump really run all winter on solar?
In mild-to-moderate climates, yes, if sized generously. Below roughly 5–15°F outdoor, most heat pumps lose efficiency right as solar generation hits its winter low — the two worst trends of the year stacking together. That overlap is why cold-climate off-grid homes usually keep a wood stove or propane furnace as cold-snap backup rather than covering the coldest week on panels alone.
Is a fully electric, no-propane off-grid home realistic?
Yes, in a mild climate with efficient appliances throughout — that’s Tier 1 above. It gets less realistic moving toward Tier 3, resistance heat and hot water in a cold climate, where the battery and array needed stop being a home project and start being a small commercial one.