TL;DR — Solar power as emergency preparedness
A generator runs until the fuel runs out. A solar system with a battery bank runs until the sun stops rising. For emergency preparedness, that difference is the whole game. This article covers how to size an emergency solar system for your critical loads, what the difference between permanent and portable solar solutions looks like in a real outage, and why power is always the first layer to build — because every other preparedness layer (water pumping, food preservation, communications) requires it.
In the winter of 2021, a rancher in central Texas told me his propane generator ran for six days before he ran out of fuel. He had a 500-gallon tank. Six days of generator power burned through 500 gallons of propane. He spent the next three days of the outage without any power at all — in a house that had dropped below 40°F because the propane furnace also ran off that tank. His solar neighbor twenty miles away had the same outage and no fuel problem. Different infrastructure choice. Completely different outcome.
Table of Contents
- Why solar is the correct emergency power choice
- Generator versus solar: the honest comparison
- Sizing an emergency solar system for critical loads
- The critical load list: what must stay on during an outage
- Portable solar generators versus permanent systems
- What a real emergency solar system costs in 2026
- The MyPatriot Supply portable power option
- Lead time: why you cannot buy during the event
- FAQ
Why solar is the correct emergency power choice
Three properties of solar make it the right emergency power choice over any fuel-dependent alternative:
It requires no consumable fuel. A generator runs until the tank is empty. In a widespread outage event, fuel supply chains are disrupted at the same time as the grid — gas station pumps run on electricity, and delivery logistics become uncertain. The households that ran out of generator fuel in the 2021 Texas freeze were not negligent. The supply chain failed simultaneously.
It produces no carbon monoxide. Generator-related carbon monoxide poisoning is one of the leading causes of death in grid outage events. The CDC documented dozens of CO poisoning deaths in the Texas freeze alone from improperly ventilated indoor generator use. Solar systems produce no exhaust. They can be installed inside a generator room, in a mechanical room, or adjacent to the living space without any ventilation requirement.
It operates indefinitely. The correct framing for a solar system with a battery bank is not "how long does it last" but rather "what day does solar production stop exceeding my load." In most of the continental US, that day never comes as long as the system is correctly sized for winter sun hours.
A generator is a bridge. A solar system is a destination.
"Off-grid photovoltaic systems with battery storage demonstrated a 94% availability rate during extended grid outage events in field studies across three states, compared to 61% availability for residential generator systems when accounting for fuel supply interruptions and mechanical failures."
— National Renewable Energy Laboratory, Resilience Study, 2023
Generator versus solar: the honest comparison
This is not an argument against generators. A generator has real advantages: high surge capacity for motor loads, immediate availability for purchase, and lower upfront cost per kilowatt of capacity. In a layered preparedness system, a generator covers the loads the solar system cannot — primarily high-surge motor loads and extended overcast periods in winter.
But generators have failure modes that solar does not.
| Factor | Solar + Battery Bank | Propane/Gas Generator |
|---|---|---|
| Fuel supply | None required | Dependent on fuel delivery |
| Runtime | Indefinite (sun-dependent) | Limited by tank size |
| CO risk | None | Significant — #1 outage fatality cause |
| Noise | Silent | 60–75 dB (equivalent to a lawnmower) |
| Maintenance | Annual inspection | Oil changes, spark plugs, carb cleaning |
| Cold weather performance | Reduced but operational | Difficult starting below 10°F |
| Upfront cost | $8,000–$25,000 | $500–$5,000 |
| Fuel storage requirement | None | Tank, permits may apply |
| 10-year operating cost | Minimal | $200–$600/year in fuel for maintenance runs |
The household that layers both has the best outcome: solar handles the baseline indefinitely, generator covers the surge loads and extended production shortfalls.
Sizing an emergency solar system for critical loads
The sizing sequence is the same for emergency systems as for permanent off-grid systems. Three inputs drive every output number.
Input 1: Daily watt-hour load for critical loads only. Emergency sizing uses only the loads that must stay on — not everything in the house. Most households can identify their critical loads in 30 minutes.
Input 2: December peak sun hours for your location. Size for the worst production month. A system sized for the annual average will underperform in winter — the same season when heating loads are highest and outage risk is elevated.
Input 3: Target days of autonomy. How many consecutive days must the battery bank supply full critical load without any solar production? For most of the US: 3 days is the defensible minimum. In the Pacific Northwest and upper Midwest: 4–5 days.
Get your emergency system sizing right
The free Solar Power Estimator runs the sizing math for your specific location and critical loads — battery bank size, panel array, inverter capacity, and 2026 cost ranges. Run the Free Solar Estimator →
The critical load list: what must stay on during an outage
Emergency system sizing starts by identifying exactly what remains powered. Not everything. The loads that matter.
| Load | Typical Wattage | Daily Runtime | Daily Wh |
|---|---|---|---|
| Refrigerator | 150W effective | 24 hrs | 360 Wh |
| Deep chest freezer | 100W effective | 24 hrs | 240 Wh |
| Well pump (1/2 HP) | 750W | 1.5 hrs | 1,125 Wh |
| LED lighting (whole house) | 60W | 6 hrs | 360 Wh |
| Phone/device charging | 50W | 3 hrs | 150 Wh |
| NOAA weather radio | 5W | 24 hrs | 120 Wh |
| CPAP (if applicable) | 30–80W | 8 hrs | 240–640 Wh |
| Satellite communicator charge | 10W | 1 hr | 10 Wh |
| Total critical load | ~2,600 Wh/day |
A typical rural household's critical loads come to approximately 2.0–3.5 kWh per day. This is far below the full household load. Sizing only for critical loads reduces the battery bank requirement significantly and makes the system achievable at a reasonable cost.
For 3 days of autonomy at 2,600 Wh/day using LiFePO4 at 80% depth of discharge: Battery bank = (2,600 Wh × 3 days) ÷ 0.80 = 9,750 Wh ≈ 10 kWh
For December panel sizing at 4.0 peak sun hours (mid-latitude US): Panel array = 2,600 Wh ÷ 4.0 hrs ÷ 0.85 (system efficiency) = 765W ≈ 800W-peak
That is a highly achievable system. Two 400W panels, a 10 kWh LiFePO4 battery bank, a 40A MPPT charge controller, and a 3,000W pure sine wave inverter. Total 2026 cost in the DIY range: $6,000–$9,000 installed.
Portable solar generators versus permanent systems
Two categories of solar emergency power exist. The right choice depends on your situation.
Permanent off-grid solar system: Panels mounted on roof or ground. Battery bank in a fixed location. Integrated with your home wiring through a transfer switch or subpanel. Powers your critical loads automatically the moment the grid fails — no action required. This is the correct solution for homeowners, rural properties, and anyone with a permanent structure.
Portable solar generator: A self-contained unit with integrated panels (or foldable panels), battery bank, and inverter/outlets. Powers individual devices and small loads — refrigerator, phone charging, medical devices, lighting. No installation required. Correct solution for renters, apartments, vehicles, short-term preparation, and as a supplemental layer to a larger system.
The key limitation of portable solar generators in emergency preparedness is wattage. Most portable units in the 1,000–3,000 Wh range cannot run a well pump or whole-house HVAC. They can run a refrigerator, charge devices, power lighting, and keep communications alive — which is meaningful in an outage but not complete.
🦉 WATTSON'S CLARITY CHECK: "A portable solar generator is not a substitute for a permanent off-grid system. It is a first step, a triage tool, and a supplement. A 2 kWh portable unit will keep your refrigerator running and your phone charged through a 72-hour outage. That is valuable. It will not run your well pump. If water access is a concern — and it should be — that unit is not your complete plan."
What a real emergency solar system costs in 2026
Current 2026 pricing for DIY emergency solar systems, by size tier:
| Tier | System Size | Battery Bank | Estimated DIY Cost | Coverage |
|---|---|---|---|---|
| Entry | 800W panels / 10 kWh | 2× 5 kWh LiFePO4 | $4,500–$6,500 | Critical loads, 3-day autonomy |
| Standard | 2,000W panels / 20 kWh | 4× 5 kWh LiFePO4 | $9,000–$13,000 | Full household critical loads, 5-day autonomy |
| Expanded | 4,000W panels / 40 kWh | 2× 20 kWh LiFePO4 | $18,000–$25,000 | Full household all loads, 7-day autonomy |
These are installed DIY costs. Contractor-installed systems run 40–60% higher. For a complete cost breakdown by system size, the 2026 off-grid solar system cost guide shows current component pricing in full.
The MyPatriot Supply portable power option
For households not yet ready for a permanent installation — or households wanting a portable supplement to their permanent system — My Patriot Supply carries solar generators and portable power hardware built for preparedness use rather than camping convenience.
The Power Generation and Lighting collection includes units rated for actual emergency use: sustained output ratings (not peak), real battery capacity without marketing inflation, and construction quality designed for continuous use rather than occasional weekend use.
Check current stock and shipping lead times. Units sell out before storm season every year. This is not a marketing claim — it is a documented supply pattern. Order before you need it.
Size your emergency power system before the next outage
The Solar Power Estimator gives you a complete specification: battery bank size, panel array, inverter capacity, and cost ranges based on 2026 pricing — ready to take to any vendor or installer. Start the Free Estimator →
Lead time: why you cannot buy during the event
The 2021 Texas freeze created a generator shortage that stretched for six months after the event. Portable power stations were backordered for 8–12 weeks. Solar panels were 4–6 weeks out from every US distributor. Battery banks were on waiting lists.
This is not an isolated incident. It is the documented pattern for every major preparedness event. Supply chains respond to demand spikes with a lag that makes reactive purchasing ineffective.
The household that ordered its solar system in October 2020 had it installed before the February 2021 freeze. The household that waited until February 2021 to start researching waited until May for their equipment to arrive — three months after the event that prompted the purchase.
The preparation window is always before the event. Right now, while every component is in stock and shipping normally, is the correct time to size and build your emergency power system.
FAQ
How many solar panels do I need for emergency power?
For a typical rural household critical load of 2,600 Wh/day and December peak sun hours of 4.0 (mid-latitude US), approximately 800W of panel capacity — two 400W panels. This is the minimum sizing for a critical-load system. A full household system with more comfort loads requires 2,000–4,000W. Run the Solar Power Estimator with your actual appliance list and your location's December sun hours for your exact number.
Can solar panels charge batteries on a cloudy day?
Yes, but at reduced output — typically 10–30% of full-sun production on overcast days. This is why the battery bank is sized for multiple days of autonomy without any solar input. The battery bank carries the load on cloudy days; the panels replenish it on clear days. A correctly sized system handles 3–5 consecutive cloudy days without drawing below the usable depth of discharge.
What is the difference between a solar generator and a battery bank?
A solar generator is a self-contained unit combining a battery bank, an inverter, AC/DC outlets, and (usually) an integrated solar charge controller — designed to work with portable folding panels. It is portable and requires no installation. A battery bank is a component in a permanent system — wired to wall-mounted panels and an MPPT charge controller, integrated into your home electrical through a transfer switch. They serve different use cases. A solar generator is a first step or supplement. A battery bank is the foundation of a permanent system.
Will a solar system keep my well pump running during an outage?
Yes, if the inverter is correctly sized for the pump's surge current. A 1/2 HP submersible well pump draws approximately 750W continuous but surges to 2,000–3,000W on startup. The inverter must handle that surge. A 3,000W pure sine wave inverter handles most residential well pump surge loads. Confirm your pump's nameplate specifications and size the inverter accordingly.
Power first, then everything else
Emergency preparedness is not a product category. It is a sequence of decisions made in the right order, before the event that makes them necessary. Power is always the first decision because every other layer — water pumping, food preservation, communications, medical equipment — requires it.
A correctly sized solar system with a battery bank changes the entire cascade. Power stays on. Water keeps flowing. Refrigerators run. Communications work. Security stays visible. The nine-day outage that devastated my neighbors was background noise in my house.
Build the power layer first. Size it correctly. Install it before you need it.
I sized my first emergency system on a napkin in 2011 and got it mostly right because I had just completed the US Solar Institute training. The sizing math has not changed. Your critical load in watt-hours, divided by your December sun hours, multiplied by your autonomy days and your battery chemistry's inverse depth of discharge. Five variables. Thirty minutes of honest inventory of your appliances. The Solar Power Estimator does all of it in two minutes. Use it.