Off-Grid Solar Inverters

An inverter converts your battery's DC power to standard 120V AC. Choose the wrong one and you'll damage your electronics — or simply have a bad time. Here's everything you need to know.

Pure Sine Wave vs Modified Sine Wave

Pure Sine Wave (PSW) Always recommended

Produces the same clean AC waveform as grid power. Safe for all electronics and appliances.

Compatible with: All motor-driven appliances (fridges, pumps, AC units), sensitive electronics, medical equipment, variable-speed tools, laptops, LED dimmers, audio equipment.

Cost: $80–$1,500+ depending on wattage. Worth every dollar.

Modified Sine Wave (MSW)

Produces a stepped approximation of AC power — cheaper to build, but problematic with many loads.

Will damage or not work with: Variable-speed motors (fridge compressors), laser printers, some battery chargers, medical devices, audio equipment (hum), LED dimmers, many CPAP machines.

Cost: $30–$200. The savings aren't worth the risk.

The rule is simple: always buy pure sine wave. Modified sine wave inverters damage motors and compressors over time, cause overheating in some devices, and can void appliance warranties. The extra cost of PSW pays for itself in protected equipment.

How to Size an Inverter

An inverter must handle two load scenarios: continuous watts and surge/startup watts.

Continuous Rating

The inverter must handle the total wattage of everything running at the same time. Add up the watts of your appliances likely to run simultaneously:

Fridge (45W) + Laptop (65W) + Lights (30W) + Water pump (60W) = 200W continuous → 300W+ inverter
Surge/Startup Rating

Motors draw 3–7× their rated watts at startup. A fridge compressor rated at 150W may pull 600–900W for 1–3 seconds on startup. Your inverter's surge rating must handle this:

Fridge surge (600W) + other loads (200W) = 800W surge needed → 1,000W+ inverter
Sizing rule of thumb: Take the largest single motor-driven appliance's peak watts, multiply by 3 for surge, then add all other simultaneous loads. Round up to the next standard size. Always leave 20% headroom.

Inverter Size Guide by Use Case

Inverter SizeUse CaseCan RunCannot Run
300–500W Van / small RV Laptop, phone, LED TV, fan, small appliances Microwave, AC unit, hair dryer
1,000–1,500W RV / cabin standard All above + coffee maker (briefly), AC fridge Microwave at full power, hair dryer, AC unit
2,000–3,000W RV full-timer / cabin All above + microwave, hair dryer, small AC Full-size AC unit (1.5+ tons), electric dryer
4,000–5,000W Home backup / off-grid All above + window AC, well pump, power tools Central AC, electric range, electric water heater
5,000–8,000W Whole-home off-grid (48V) Almost anything except heavy HVAC loads Electric dryer, large electric range (at full power)

Inverter/Charger Combos

For any system with a generator or grid connection, an inverter/charger is the better choice. It combines:

  • Inverter — converts battery DC to AC output
  • Battery charger — charges batteries from AC input (generator or shore power)
  • Transfer switch — automatically switches between battery/solar and AC input with near-zero interruption

This eliminates the need for a separate battery charger and a manual transfer switch — saving money and complexity.

Top Inverter Picks

Renogy 2000W Pure Sine Wave Inverter
  • 2,000W continuous, 4,000W surge
  • 12V or 24V DC input versions
  • USB ports + 3× AC outlets
  • Best budget PSW inverter at this wattage

~$200

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Victron MultiPlus-II 48/3000
  • 3,000W inverter + 35A charger combined
  • 48V system (ideal for home/cabin)
  • Generator auto-start relay included
  • Grid-tie / ESS capable
  • Industry-standard reliability

~$1,100

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Renogy 1000W Pure Sine Wave Inverter
  • 1,000W continuous, 2,000W surge
  • Good for RV and van builds
  • 12V input
  • Compact, affordable

~$130

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Growatt SPF 5000ES (48V)
  • 5,000W inverter/charger, 48V
  • Built-in 80A MPPT charge controller
  • Popular budget all-in-one for home systems
  • LCD display, WiFi monitoring optional

~$700

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Installation Tips

  • Mount close to the battery: The DC cable from battery to inverter carries enormous current. A 2,000W inverter at 12V draws ~170A — keep cable under 3 feet and size appropriately (2/0 AWG or larger).
  • Fuse close to the battery: Place a fuse or ANL fuse holder within 12–18 inches of the battery's positive terminal. For a 2,000W/12V inverter: use a 200A fuse.
  • Ventilation: Inverters generate heat proportional to load. Never install in a sealed enclosure. Ensure at least 2–3 inches of clearance on all sides.
  • Ground the chassis: Connect the inverter's chassis ground to the vehicle/building's chassis/earth ground to prevent electric shock hazards.

Need to find the right inverter size?

Our system calculator determines your peak load and recommends the correct inverter wattage for your specific appliances.

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