Off-grid by project · Full homes
Off-grid home solar: how to power a whole house without the grid
A full-time off-grid home is the biggest system you can build. The choices that matter most are which jobs go to propane, how you get through winter, and how big a generator you keep.
At a glance
The biggest loads decide the system
A handful of appliances use most of a home's energy. Each one you move to propane or wood, or run only when the sun is out, shrinks the panels and battery you need.
Typical values from the appliance wattage chart. Your appliances' labels and your climate will change these.
Two example homes
These use 400 W panels and the same sizing math as the off-grid planner.
Efficient off-grid home: 8.21 kWh a day
A family home with a well, washer, dishwasher and a gas dryer. Propane or wood covers heat, cooking and hot water.
| Season | 400 W panels | Battery (2 days) | Battery (3 days) |
|---|---|---|---|
| 5 sun hours (summer) | 7 (2.8 kW) | 24.62 kWh | 36.95 kWh |
| 2.5 sun hours (winter) | 13 (5.2 kW) | 24.62 kWh | 36.95 kWh |
Inverter: the loads likely to run at the same time total 4,000 W, so plan about 5,000 W continuous and 7,000 W surge. That covers the well pump starting while the washer, fridge and microwave run. The dishwasher, dryer and coffee maker can wait.
All-electric off-grid home: 21.31 kWh a day
Swaps propane for a ductless mini-split, an electric range and an electric dryer.
| Season | 400 W panels | Battery (2 days) | Battery (3 days) |
|---|---|---|---|
| 5 sun hours (summer) | 16 (6.4 kW) | 63.93 kWh | 95.9 kWh |
| 2.5 sun hours (winter) | 32 (12.8 kW) | 63.93 kWh | 95.9 kWh |
Inverter: the loads likely to run at the same time total 6,400 W, so plan about 8,000 W continuous and 9,400 W surge. That covers the well pump starting while the range, mini-split and washer run. Save the dryer for sunny middays when nothing else big is on.
Size your own off-grid home
- Daily use
- 8.21 kWh
- Battery (2 days)
- 24.62 kWh
- Inverter
- 8,075 W
- Startup surge
- 9,460 W
Uses the same math as the off-grid planner at 4 peak sun hours. A planning estimate, not a design.
The calculator's inverter figure assumes every selected appliance runs at once. Size the real inverter from what runs together, as in the examples above.
How a whole-home system fits together
- Ground or roof arraySized for the darkest month
- Charge controllersOne or more MPPT units
- 48V battery bankConditioned space, fire-rated
- Split-phase inverter/charger120/240V, often stacked
- Main panel and loadsPermitted and inspected
A backup generator connects to the inverter/charger, which starts it automatically when the battery runs low. Disconnects and overcurrent protection sit between every stage.
What's different about a full-time home
- 240V split-phase is standard. Submersible well pumps, ranges, dryers and many mini-splits run on 240V. Use a split-phase inverter or a stacked pair, and see inverter sizing.
- The well pump sets the surge. A 1 hp submersible pump can surge to 4,500 W. A soft starter or variable-speed pump cuts that sharply.
- 48V batteries. At whole-home power, 12V or 24V means very high current and huge cables. Nearly every home system is 48V.
- A generator is part of the design. An auto-start generator connected to the inverter/charger covers long storms for far less than extra panels and batteries. Plan its fuel and where it sits.
Manage the big loads
- Run heavy loads at midday. Laundry, dishwashing, water pumping and EV charging use solar directly when the panels are producing.
- Stagger motors. Don't let the well pump, washer and air conditioner start at the same moment.
- Use load control. Many inverters and smart panels can switch off non-essential circuits when the battery is low.
- Plan for winter. Short days can double the panels you need. A steep ground-mount tilt and a generator help. See off-grid solar in winter.
Off-grid or grid-tied?
If utility power is nearby, a grid connection is almost always cheaper than a full off-grid system, and you can still add solar to cut your bill. Use the home solar calculator for that. Off-grid makes sense when bringing in the grid is expensive or impossible. Get a quote for a line extension before you decide.
Permits and professional help
A whole-home off-grid system is a permanent electrical installation. Expect a permit, plan review and inspection, and a licensed electrician or solar installer for the battery bank, inverter, main panel and generator connection. Lenders and insurers often ask for the inspection too. Use this guide and the planner to size the system and compare options, then get installer quotes. The DIY vs. professional guide shows which parts you can safely do yourself.
FAQ
Can you run a whole house on off-grid solar?
Yes. An efficient home that uses propane for heat, cooking and hot water needs about 8.21 kWh a day, or 7 × 400 W panels in summer and 13 in winter. Going all-electric raises that to about 21.31 kWh a day and 32 panels in winter.
How big a battery does an off-grid house need?
Plan two to three days of storage. That's about 25–37 kWh for an efficient propane home and 64–96 kWh for an all-electric one. Most off-grid homes also keep a generator for long cloudy stretches instead of buying more battery.
What size inverter does an off-grid home need?
Most need a 120/240V split-phase inverter, either one large unit or two stacked. The examples here need about 5,000 W continuous for the efficient home and 8,000 W for the all-electric one, with 9,400 W of surge to start a 1,500 W well pump while other loads run.
Is off-grid cheaper than connecting to the grid?
Only when the utility line is far away. If power lines are close, a grid connection is usually cheaper, and grid-tied solar can still cut your bill. Get a quote for running power to the site before you decide.
Do I need a permit for an off-grid home solar system?
Almost always. A whole-home system is a permanent electrical installation that needs a permit, inspection and usually a licensed electrician. Lenders and insurers often require it too.