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Solar Generator Calculator

Solar Generator Size Calculator

Find the right solar generator for your needs. Calculate daily watt-hours, required panel wattage, battery capacity, and get matched to specific solar generator models.

8 models
matched automatically
Peak sun
by US region
LiFePO4
battery math included

☀️ Step 1: Your Daily Power Needs

Select appliances running ~8 hours/day, or enter a custom watt-hour total.

🧊
Refrigerator
150W × 8h = 1200 Wh/day
❄️
Window AC (10,000 BTU)
1200W × 8h = 9600 Wh/day
❄️
Portable AC
1100W × 8h = 8800 Wh/day
💨
Ceiling Fan
60W × 8h = 480 Wh/day
💡
LED Lights (10 bulbs)
100W × 8h = 800 Wh/day
📺
TV (65" Smart TV)
120W × 8h = 960 Wh/day
💻
Laptop
65W × 8h = 520 Wh/day
📡
Router / Modem
20W × 8h = 160 Wh/day
💧
Well Pump (1 HP)
750W × 8h = 6000 Wh/day
Sump Pump
800W × 8h = 6400 Wh/day
Wh/day
Total Daily Need
0
Wh/day

🔆 Step 2: Solar Configuration

50W1,500W3,000W
100 Wh5,000 Wh10,000 Wh
☀️

Select appliances above to see your solar generator recommendation.

Peak Sun Hours by US Region

RegionPeak Sun Hours
Southwest (High)6.5h
Southeast5.5h
Pacific Coast5h
Central Plains5h
Mountain5.5h
Midwest4.5h
Mid-Atlantic4.5h
New England4h
Pacific Northwest3.5h
Alaska2.5h

Solar Generators vs. Gas Generators: When to Choose Each

Solar generators (battery power stations with solar charging) and gas generators serve different use cases. Understanding the tradeoffs helps you pick the right tool.

FactorSolar GeneratorGas Generator
NoiseSilent65–75 dBA
Indoor use✅ Safe indoors❌ Outdoor only
Fuel costFree (sun)$1–5/hour
Capacity100–5,100 WhUnlimited (on fuel)
Upfront cost$250–$4,500$400–$2,500
MaintenanceNoneOil, filters, carb
Cloudy daysLimited rechargeNo impact
Best forCamping, indoor backup, RV, van lifeExtended outages, high wattage loads

For most homeowners and campers, a solar generator makes excellent sense for loads under 2,000–3,000 Wh/day, especially if those loads include sensitive electronics or require silent, indoor-safe operation. For multi-day outages or high-wattage loads (well pump, central AC, electric dryer), a gas or propane generator remains more practical.

Maximizing Solar Generator Performance

  • Angle your panels correctly. Panels aimed directly at the sun produce 20–40% more power than flat panels. A 45° angle toward the south (in the northern hemisphere) is optimal for fixed setups.
  • Avoid shade entirely. Even partial shade on one panel can reduce output by 50–80% depending on the system.
  • Charge from wall when possible. Use AC charging overnight when grid power is available, solar during the day. Most solar generators support pass-through charging.
  • Monitor your state of charge. LiFePO4 batteries last longest when kept between 20–90% charge. Avoid running to 0% regularly.

Solar Generator vs. Conventional Generator

When Solar Generators Make Sense

Solar generators (a solar panel array charging a battery bank, with an inverter for AC output) are an excellent choice for low-to-medium power needs where silent operation, zero emissions, and no fuel storage matter most. They are, therefore, ideal for camping, RV travel, outdoor events, small cabin backup, and medical device backup (CPAP machines, oxygen concentrators). However, for powering central air conditioning, well pumps, or an entire home during an extended outage, a solar generator's battery capacity is typically insufficient unless paired with a very large (and expensive) battery bank.

Understanding Watt-Hours vs. Watts

Solar generators are rated in watt-hours (Wh) — the amount of energy stored — rather than watts (the rate of power delivery). A 1,000Wh battery can deliver 100W for 10 hours, or 1,000W for 1 hour. Consequently, to size a solar generator, calculate your daily energy consumption in watt-hours — not just your peak wattage. Furthermore, factor in the depth of discharge: most LiFePO4 batteries can safely discharge to 20% capacity, giving you 80% of rated Wh as usable energy.

Solar Panel Sizing Formula

Required solar panel wattage = Daily Wh needed ÷ (Average peak sun hours × 0.85 system efficiency). For example, if you need 1,000Wh per day and get 5 peak sun hours (US average): 1,000 ÷ (5 × 0.85) = 235W of solar panel capacity. Additionally, add 20–30% overhead for cloudy days and seasonal variation if you rely on solar as a primary power source rather than occasional backup. The calculator above applies this formula automatically using the NREL PVWatts methodology.

Battery Technology for Solar Generators

LiFePO4 vs. Lead-Acid Batteries

LiFePO4 (lithium iron phosphate) batteries now dominate the solar generator market for residential use, and for good reason. Compared to lead-acid alternatives, LiFePO4 offers 3,000–5,000+ charge cycles vs. 300–500 for lead-acid, a usable depth of discharge of 80% vs. 50% for lead-acid, and superior safety (no thermal runaway, no off-gassing). Furthermore, LiFePO4 batteries maintain consistent voltage throughout discharge, whereas lead-acid batteries show a declining voltage curve that reduces effective capacity. As a result, while LiFePO4 costs more upfront, the 10× longer cycle life makes it significantly cheaper per kWh delivered over the battery's lifespan.

Top Solar Generator Brands

Jackery, EcoFlow, Bluetti, and Goal Zero are the established brands in the residential solar generator market. EcoFlow's DELTA series leads for fast charging (0 to 80% in 1 hour via AC input) and high output surge capacity. Jackery is the most popular brand for camping and RV use due to its wide panel compatibility and ease of use. However, for home backup applications requiring 3,000+ Wh capacity and 2,000W+ AC output, the EcoFlow DELTA Pro or Bluetti AC300 are better fits.

Need a Traditional Generator Too?

Compare solar generator options with traditional gas generators using our main sizing calculator.

Generator Size Calculator

Frequently Asked Questions

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