Solar Power for a Full-Time Off-Grid Homestead
By Matt · Updated
The short answer
A full-time homestead runs 7 to 15 kWh a day once a well pump, freezers, and a workshop are included, which is several times a cabin. At that scale 48 volts stops being a preference and becomes the only sensible choice, and a generator is almost always cheaper than the last two days of storage.
The worked system
A full-time off-grid household with a drilled well, a chest freezer, a workshop, and outbuildings. Propane for cooking and hot water, wood for heat. Sized for December.
Daily loads
| Load | Watts | Hours | Duty | Wh/day |
|---|---|---|---|---|
| Refrigerator | 150 | 24 | 0.35 | 1,260 |
| Chest freezer | 120 | 24 | 0.3 | 864 |
| Deep well pump | 1,200 | 1 | 1 | 1,200 |
| LED lighting ×14 | 10 | 6 | 1 | 840 |
| Washing machine | 500 | 1 | 1 | 500 |
| Computers and networking | 150 | 8 | 1 | 1,200 |
| Television and audio | 120 | 4 | 1 | 480 |
| Workshop tools and charging | 400 | 1.5 | 1 | 600 |
| Ventilation and circulation fans | 80 | 10 | 1 | 800 |
| Small appliances | 300 | 1 | 1 | 300 |
| Total | 8,044 Wh | |||
What that needs
- Solar array
- 4,022 W
- Battery bank
- 524 Ah at 48 V
- Usable storage
- 16.1 kWh
- Charge controller
- 105 A minimum
- Inverter, continuous
- 4,000 W
- Must also surge to
- 5,960 W
An inverter has two ratings and both have to hold. The continuous figure covers everything running at once; the surge figure covers the largest motor starting on top of that, for a few seconds. Most inverters surge to roughly twice their continuous rating, but check the specification rather than assuming, because an inverter that cannot supply the surge will not start the appliance at all.
Sized on 2.5 peak sun hours, 2 days of autonomy, and LiFePO4 at its recommended depth of discharge. The bank includes a 25% margin for inverter losses, cold weather, and aging.
Every figure above is computed by the same calculators this site publishes, not typed in. To change any assumption, put your own numbers into the appliance power budget and the system sizing calculator.
This is the scale at which off-grid stops being a hobby project. A full-time homestead with a well, freezers, and a workshop is several times a cabin, and the decisions that were preferences at smaller sizes become constraints.
The well pump changes the design
On the load list above, the deep well pump is not the biggest energy consumer. The refrigeration is. But it is by far the biggest influence on the inverter, and it is the load most likely to cause trouble.
Deep well pumps start hard. A pump drawing 1,200 W running can surge to several times that for the moment it starts, and it starts every time pressure drops. An inverter that cannot supply that surge will either stall the pump or shut down, and you find out when you have no water.
Three things help:
Get the real figure. Nameplate running watts tell you little. Pump specifications list locked-rotor or starting current, and that is the number the inverter has to survive.
Consider a soft starter, which reduces the surge substantially and is far cheaper than the extra inverter capacity it saves.
Use a bigger pressure tank. A larger tank means the pump runs less often and for longer each time, which is easier on the pump, the inverter, and the bank.
Why 48 volts is not optional here
At 24 V, a 6,000 W inverter draws about 250 A at full output. That is very heavy cable, large and expensive fuses, and meaningful energy lost as heat in the conductors.
The same inverter at 48 V draws about 125 A. Halving the current halves the conductor requirement, and the cable saving alone often exceeds any price difference in the equipment. Above roughly 3,000 W of inverter, most equipment is 48 V anyway.
This is also the scale where wire sizing stops being a detail and becomes a significant line item. Run the numbers before buying anything.
Two days of autonomy, and a generator
The scenario uses two days rather than the four or five that a purist design might. That is deliberate, and it is the single biggest cost decision on a system this size.
Storage scales linearly with autonomy, and at homestead consumption each extra day is a large sum. It is also capacity you use a handful of times a year, and it does not solve the case that actually strands people: a week of snow on the array.
A generator covers the rare gap for a fraction of what the equivalent storage costs, and it covers the snow case that no amount of battery does. Most long-running off-grid homes have one, and that is an engineering conclusion rather than a compromise.
A hybrid inverter/charger makes this practical, since it manages the switching and can charge the bank from the generator automatically.
Sized for December
The scenario uses 2.5 peak sun hours, which is a northern winter figure rather than an annual average.
This matters more at homestead scale than anywhere else, because the consequence of being short is not inconvenience. It is a full-time household without water or refrigeration. Look up the December figure for your latitude and use that.
The corollary is that such a system is heavily oversized in June. That is normal and unavoidable for a year-round off-grid house, and it is why surplus summer production often gets spent on things that would otherwise use propane.
What keeps the number down
The load list assumes propane for cooking and hot water and wood for heat. Those three jobs done electrically would multiply this system several times over, because they are all measured in kilowatts.
Two other things matter at this scale:
Refrigeration is the largest continuous load. A fridge and a chest freezer together run all year, and efficient units are worth real money here because you pay for their consumption in panels and batteries.
Phantom loads add up across a larger building. Every device with a standby light, every charger left plugged in, and the inverter’s own idle draw all run continuously. On a homestead these can total a meaningful fraction of a kilowatt-hour a day.
Adjusting this
Everything in the specification is computed from the load list rather than typed in. Homesteads vary more than any other category on this site, so put your own loads into the appliance power budget and the total into system sizing.
Before committing to a bank, read how to size a battery bank and check the array can genuinely refill what you are buying.
Common questions
- How much solar does a full-time off-grid house need?
- Most land between 7 and 15 kWh a day once a well, freezers, and outbuildings are included, which typically means 4 to 8 kW of array and 15 to 30 kWh of storage. The range is wide because it depends almost entirely on what is done with propane and wood rather than electricity.
- Why 48 volts rather than 24?
- Current. At this scale a 24 V system moves currents that need very heavy and expensive cable and large fuses, and most inverters above about 3,000 W are 48 V anyway. Halving the current halves the conductor cost and the losses.
- Do I need a generator?
- Almost certainly, and it is an economic decision rather than a failure. The last two days of storage are the most expensive and least used part of a bank. A generator covers the rare long gap and the week the array is under snow, for a fraction of the cost.
- What about the well pump?
- It is usually the largest single influence on the inverter, though not on the energy budget. A deep well pump can surge to several times its running current. Get the actual figure from the pump before sizing anything, and consider a soft starter or a pressure tank so it runs less often.