The Short Answer
For basic outage protection (refrigerator, lights, phone charging, WiFi), most homes need 2–4 solar panels (600W–1,200W) paired with a battery system that stores at least 5kWh. Total cost: $2,000–$6,000.
For full off-grid capability (running everything including HVAC), you'll need 10–20+ panels and 20–40kWh of battery storage. Total cost: $15,000–$40,000+.
Let's break down how to calculate your specific needs.
Step 1: Calculate Your Essential Load
During a grid outage, you won't power everything - you'll prioritize essentials. Here's what most homeowners consider essential and their approximate power usage:
| Appliance | Watts | Hours/Day | Daily Wh |
|---|---|---|---|
| Refrigerator | 150W | 8 (cycles) | 1,200 |
| LED Lights (5) | 50W | 6 | 300 |
| Phone chargers (2) | 20W | 3 | 60 |
| WiFi router | 15W | 24 | 360 |
| Laptop | 60W | 4 | 240 |
| Fan (1) | 50W | 8 | 400 |
| Total | 2,560 Wh |
So a typical household needs about 2.5kWh per day for bare essentials - or roughly 5kWh if you want some comfort items like a TV, coffee maker, or microwave (used sparingly).
Step 2: Factor In Solar Production
Solar panels don't produce their rated power all day. A 400W panel in a sunny state like Texas or California might produce 1,600Wh per day (4 peak sun hours). In a cloudier state like Ohio or Washington, it might produce only 1,000Wh per day (2.5 peak sun hours).
Average peak sun hours by region:
- Southwest (AZ, NV, NM): 6–7 hours
- South (TX, FL, CA): 4–5 hours
- Midwest (OH, IL, IN): 3–4 hours
- Northeast (NY, PA, MA): 3–3.5 hours
- Northwest (WA, OR): 2.5–3 hours
Step 3: Calculate Panels Needed
Using the formula: Panels = Daily energy need / (panel wattage x peak sun hours)
Example for Texas (4.5 peak sun hours), 5kWh daily need:
- Panels = 5,000Wh / (400W x 4.5h) = 2.8 panels
- Round up: 3 panels (1,200W system)
Example for Ohio (3.5 peak sun hours), 5kWh daily need:
- Panels = 5,000Wh / (400W x 3.5h) = 3.6 panels
- Round up: 4 panels (1,600W system)
Step 4: Size Your Battery Storage
Your battery needs to store enough energy for nighttime use and cloudy days. A good rule of thumb is 1.5–2x your daily energy need.
For our 5kWh daily example: 7.5–10kWh of battery storage.
Popular battery options:
- EcoFlow DELTA Pro (3.6kWh): $2,399 - need 2-3 units
- Tesla Powerwall (13.5kWh): ~$8,500 installed
- Enphase IQ Battery (10.08kWh): ~$7,000 installed
Step 5: Total Cost Estimate
| Component | Budget Option | Mid-Range | Premium |
|---|---|---|---|
| Solar panels (3-4) | $800–$1,200 | $1,200–$1,800 | $1,800–$2,400 |
| Battery storage | $1,000–$2,400 | $2,400–$5,000 | $7,000–$12,000 |
| Inverter/charger | $200–$500 | Included | Included |
| Installation | DIY | $1,000–$2,000 | $2,000–$4,000 |
| Total | $2,000–$4,100 | $4,600–$8,800 | $10,800–$18,400 |
The Easiest Starting Point
If you're new to solar backup, the simplest entry point is a portable power station with a foldable solar panel. No installation, no permits, no electrician needed.
Starter kit example:
- EcoFlow DELTA 2 ($999) + 220W solar panel ($449) = $1,448 total
- Provides: 1,024Wh storage, recharges in 4–6 hours of sun
- Powers: Refrigerator + lights + phones for 5–8 hours
State Incentives Can Lower Your Cost
Many states offer tax credits and rebates for solar and battery installations. The federal Investment Tax Credit (ITC) still covers 30% of solar installation costs. Some states add their own incentives on top of that.
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