Solar panels on an RV roof in the desert

What Size Solar Panel Do I Need?

Free calculator for RV, van, cabin, and off-grid systems. Get your panel, battery, and inverter sizing in 2 minutes.

Quick Answer: What Solar Panel Size Do You Need?

For a typical RV or van setup using 2,400Wh per day, you need 400–600W of solar panels, a 200Ah LiFePO4 battery bank at 12V, a 40A MPPT charge controller, and a 2,000W pure sine wave inverter. In most of the US (5 peak sun hours), 400W of panels replenishes 1,500Wh daily after system losses. The EcoFlow Delta 2 + 220W Solar Panel ($1,098) handles this as a plug-and-play solution. For DIY builders, two Renogy 200W panels paired with a 200Ah LiTime LiFePO4 battery and a Renogy 40A MPPT controller covers the same load for about $900. Weekend campers with under 600Wh/day needs do well with a single 100W panel and a 100Ah LiFePO4 battery for under $350.

Solar System Size Calculator

Enter your appliances and location to get a personalized recommendation.

Use Case

Loads

Location

Results

What are you powering?

Select a use case to pre-fill common appliances, or choose Custom Load List to start from scratch.

Solar Panel Size Quick Reference

Common use cases with recommended panel wattage, battery size, and EcoFlow equivalent for each scenario.

Use Case	Daily Energy	Panel Watts	Battery (LiFePO4)	EcoFlow Alternative
Weekend camping	300–600Wh	100–200W	100Ah 12V LiFePO4	EcoFlow River 2 + 110W
RV full-time	1,500–2,500Wh	400–600W	200Ah 12V LiFePO4	EcoFlow Delta 2 + 220W
Van life	800–1,500Wh	200–400W	100–200Ah 12V LiFePO4	EcoFlow River 2 Pro + 220W
Off-grid cabin	3,000–5,000Wh	800–1,200W	400Ah 24V LiFePO4	EcoFlow Delta Pro + 400W
Emergency backup	500–1,000Wh	200–300W	100Ah 12V LiFePO4	EcoFlow Delta 2 + 110W
Single fridge	1,200Wh	400W	100Ah 12V LiFePO4	EcoFlow Delta 2 + 220W
CPAP / medical	150–300Wh	100W	50–100Ah 12V LiFePO4	EcoFlow River 2 + 110W
Starlink	720Wh (30W x 24h)	200W	100Ah 12V LiFePO4	EcoFlow River 2 Pro + 110W

Frequently Asked Questions

How many solar panels do I need for an RV?+

Most RV setups run comfortably on 400–600 watts of solar. A typical daily load — 12V compressor fridge (1.2 kWh), LED lights (300Wh), laptop (480Wh), fan (400Wh), and phone charging — totals about 2.4 kWh per day. Divide by 5 peak sun hours and a 0.75 real-world derate factor, and you need 640 watts of panels. Two 300W panels wired in series through a 40A MPPT charge controller is the standard setup. Pair with a 200Ah LiFePO4 battery at 12V for two days of autonomy. The EcoFlow Delta 2 with a 220W solar panel is the plug-and-play alternative if you want zero wiring.

What size solar panel do I need to run a refrigerator?+

A standard full-size refrigerator consumes about 1.2 kWh per day after accounting for its 33% compressor duty cycle. To replenish that daily in a 5-sun-hour region, you need roughly 320 watts of solar — a single 400W panel covers it cleanly. In the Pacific Northwest or during winter months, plan for 600 watts of panels total. Pair the panels with a 200Ah LiFePO4 battery at 12V to handle two days of overcast weather without the fridge warming up. The EcoFlow Delta 2 Max with one 220W solar panel keeps a single fridge running indefinitely in most US regions.

How do I calculate the solar panel size I need?+

Start by totaling your daily energy use in watt-hours: for each appliance, multiply watts by hours used per day. Add 20% for system losses to get adjusted daily watt-hours. Divide that number by your location's peak sun hours (4.0–6.5 for most of the US) and multiply by 1.33 (to account for real-world panel derating from heat, dust, and wiring). The result is your minimum panel wattage. Round up to the nearest 100W. For battery sizing, multiply adjusted daily watt-hours by your desired days of autonomy, then divide by 0.8 for LiFePO4 (or 0.5 for AGM). Divide by system voltage to get amp-hours.

What size battery do I need for a solar system?+

Battery sizing depends on daily energy use and desired cloudy-day autonomy. Multiply your daily watt-hours by the number of autonomy days, then divide by depth of discharge: 0.8 for LiFePO4, or 0.5 for AGM. For a 2,000Wh/day system with 2 days autonomy and LiFePO4: (2,000 × 2) / 0.8 = 5,000Wh of battery. Divide by system voltage for amp-hours: 5,000 / 12 = 417Ah at 12V, or 5,000 / 24 = 208Ah at 24V. Systems under 2kWh/day work well at 12V. Systems from 2–6kWh/day benefit from 24V. Above 6kWh/day, use 48V to keep wire gauge manageable.

MPPT vs PWM: which charge controller do I need?+

Use MPPT for any system larger than 200 watts. MPPT controllers extract 15–30% more energy from your panels by continuously tracking their maximum power point — they convert excess panel voltage into additional charge current. PWM controllers are simpler and cheaper, but they waste panel capacity whenever the panel voltage is higher than the battery voltage. On a 12V system with 12V nominal panels, the difference is small. But on any system with higher-voltage panels, 24V banks, or roof arrays over 200W, MPPT pays for itself in recovered energy within the first year. The Renogy Rover 40A MPPT and Victron SmartSolar 100/30 are the top two recommendations.

How many watts of solar panels do I need for 1000Wh per day?+

To generate 1,000Wh per day, you need: 1,000 / (peak sun hours × 0.75). In the Southwest US at 6.5 peak sun hours: 1,000 / (6.5 × 0.75) = 205W. In the Northeast US at 4.5 peak sun hours: 1,000 / (4.5 × 0.75) = 296W. In the Pacific Northwest at 4.0 peak sun hours: 333W. Always round up to the next available panel size. For 1,000Wh/day in most of the US, a single 300W or 400W panel is sufficient. This covers a laptop running 8 hours, phone charging, a router, and LED lighting for a van or studio apartment.

Can I run an air conditioner on solar panels?+

Yes, but it requires a large system. A 10,000 BTU window AC draws about 1,200W with a 3,600W startup surge and runs at 50% duty cycle. Running it 8 hours uses about 4,800Wh per day. That requires 1,280–1,500W of solar panels, a 200Ah 48V LiFePO4 battery bank, and a 3,600W pure sine wave inverter capable of handling the startup surge. The EcoFlow Delta Pro Ultra is the only all-in-one unit that handles air conditioning. Budget $5,000–10,000 for a DIY AC-capable solar system. For a van or tiny space, a 12V portable AC like the BougeRV Portable AC (700W) is far more practical.

What size solar system do I need for a cabin?+

An off-grid cabin with a fridge, lights, laptop, TV, microwave, and coffee maker uses 3,500–4,500Wh per day. At 5 peak sun hours, that needs 930–1,200W of solar panels. Round up to six 200W panels (1,200W total). Battery sizing for 3 days of autonomy with LiFePO4: (4,000 × 3) / 0.8 = 15,000Wh — roughly a 625Ah 24V bank. Use a 60A MPPT charge controller and a 3,000W pure sine wave inverter. Apply a 1.5x winter multiplier for year-round northern US cabin use and install 1,800W of panels. The EcoFlow Delta 2 Max serves as a good transitional system while you build the permanent install.

How long do solar panels last?+

Quality monocrystalline solar panels last 25–30 years with gradual output degradation of 0.5–0.7% per year. After 25 years, a good panel still produces 83–87% of its original rated output. Renogy, BougeRV, SunPower, and Canadian Solar all publish 25-year linear power output warranties. Panels rarely fail catastrophically — they typically degrade slowly and continue producing useful power well beyond warranty. The other system components are shorter-lived: LiFePO4 batteries last 8–15 years (2,000–4,000 cycles), MPPT charge controllers last 10–15 years, and inverters last 5–12 years. Plan replacement budgets for inverters and batteries, not panels.

Do solar panels work on cloudy days?+

Yes, but at reduced output. On a heavy overcast day, panels produce 10–25% of their rated output. On a light overcast or hazy day, output is 50–70% of rated. This is why battery storage for 2–3 cloudy days is the standard recommendation — the batteries absorb the shortfall while the panels still contribute meaningfully. Germany, with notoriously overcast weather, is one of the world's top solar energy producers because high-efficiency panels and adequate battery storage compensate for lower sun hours. In the Pacific Northwest (Seattle), 4.0 average peak sun hours accounts for frequent clouds — size panels conservatively there.

What is the best budget solar panel setup?+

The best budget solar panel setup for 2024 is: one 200W Renogy or Newpowa monocrystalline panel ($80–100), a 20A Renogy Wanderer MPPT charge controller ($45), a 100Ah Weize AGM battery ($120), and a Bestek 300W pure sine wave inverter ($35). Total: around $300 for a system that generates 800–1,000Wh per day and runs lights, a phone charger, a laptop, and a fan. For the next step up, replace the AGM with a 100Ah LiTime LiFePO4 ($200) for twice the usable capacity. Budget solar works extremely well for simple, defined loads — the key is not over-building.

EcoFlow vs DIY solar: which is better?+

EcoFlow power stations beat DIY solar on simplicity, warranty, portability, and speed of setup. You plug in a panel and go. The EcoFlow Delta 2 costs $899 ($600 on sale) and includes everything: battery, BMS, inverter, MPPT charge controller, and all protection. DIY beats EcoFlow on expandability, cost per watt-hour (about 40% cheaper at scale), repairability, and maximum system size. For systems under 3 kWh, EcoFlow is hard to beat for the money. For systems above 5 kWh, DIY with Renogy or Victron components is cost-effective and allows expansion. Many users start with an EcoFlow Delta 2 and later transition to a full DIY system as their needs grow.

What is the difference between LiFePO4 and AGM batteries for solar?+

LiFePO4 (lithium iron phosphate) batteries are better than AGM in almost every metric except upfront cost. LiFePO4 allows 80% depth of discharge versus 50% for AGM, meaning a 100Ah LiFePO4 stores 80Ah of usable energy versus 50Ah for an AGM. LiFePO4 lasts 2,000–4,000 cycles versus 300–500 for AGM, making it 3–5x cheaper per cycle over its lifetime. LiFePO4 charges 3–5x faster, tolerates partial states of charge without damage, and works well in temperatures down to 32°F (most have a low-temperature cutoff). AGM makes sense only for static backup systems that rarely discharge deeply, or for extremely budget-constrained small systems.

How much does a complete off-grid solar system cost?+

A basic van or RV system (400W panels, 200Ah LiFePO4, 40A MPPT, 2,000W inverter) costs $1,200–1,800 for components. A cabin system (1,200W panels, 400Ah 24V LiFePO4, 60A MPPT, 3,000W inverter) costs $4,000–7,000. A small whole-home system (5kW panels, 20kWh LiFePO4, Victron equipment) costs $15,000–25,000 installed. EcoFlow turnkey solutions: River 2 Pro + 110W panel ($649), Delta 2 + 220W panel ($1,099), Delta 2 Max + 400W panel ($1,799), Delta Pro + 400W panel ($2,799). Panel prices have dropped 80% in the past decade and continue falling — early 2024 is one of the best times in history to build a solar system.

Size Solar for Your Use Case

Tailored solar sizing guides for every off-grid scenario.

RV Solar

5.5 peak sun hrs · 12V system

Van Build Solar

5.5 peak sun hrs · 12V system

Off-Grid Cabin Solar

5 peak sun hrs · 24V system

Tiny Home Solar

5 peak sun hrs · 24V system

Shed / Workshop Solar

5 peak sun hrs · 12V system

Emergency Backup Solar

4.5 peak sun hrs · 48V system

CPAP Solar

5 peak sun hrs · 12V system

Starlink Off-Grid Solar

5 peak sun hrs · 12V system

Boat / Marine Solar

6 peak sun hrs · 12V system

Well Pump Solar

5 peak sun hrs · 12V system

Solar Sizing by Appliance

How many solar panels do you need to run each appliance?

Refrigerator

150W

LED Lights (5 bulbs)

50W

Laptop

60W

Smartphone Charging

15W

Starlink Satellite Internet

75W

CPAP Machine

60W

Microwave

1000W

Coffee Maker

900W

Television (32–55")

100W

Box Fan / Ceiling Fan

50W

Recommended Solar Systems

Pre-sized system specs for the most common off-grid scenarios.

Best 400W Solar System for RV Living (LiFePO4 Build)

400W · 200Ah

Best 200W Solar System for Van Builds (Compact, Lightweight)

200W · 100Ah

Best 1,000W Solar System for Off-Grid Cabin (24V)

1000W · 375Ah

Best 2,000W Solar System for Off-Grid Cabin (24V Full-Featured Build)

2000W · 430Ah

Best 200W Solar System for a Backyard Shed

200W · 100Ah

Best 1,000W Solar Emergency Backup System for Home

800W · 219Ah

Best 3,000W Whole-Home Solar Emergency Backup System

2000W · 469Ah

Off-Grid Solar System for Starlink (Complete System Spec)

700W · 261Ah

Best Portable Solar System for Running a CPAP (Camping and Travel)

100W · 60Ah

Complete Solar System for a 1HP Well Pump (Off-Grid)

1200W · 313Ah

Best 1,000–2,000W Solar System for Tiny Homes

1000W · 198Ah

Best 200W Solar System for Sailboats and Marine Use

300W · 234Ah

Best 100W Portable Solar System for Camping

100W · 83Ah

Minimum Solar System for Running a Refrigerator Off-Grid

400W · 125Ah

Complete 5kW Whole-Home Off-Grid Solar System Design

5000W · 938Ah

Compare Solar Products

Head-to-head comparisons to help you choose the right gear.

EcoFlow Delta 2 vs Jackery Explorer 1000 Pro: Full Comparison

Winner: EcoFlow Delta 2

Renogy 200W vs BougeRV 200W Solar Panel: Full Comparison

Winner: Renogy 200W Monocrystalline

LiFePO4 vs AGM Battery for Solar Systems: Which Should You Buy?

Winner: LiFePO4

Solar Guides

Deep-dive guides on solar system design and component selection.

How to Size a Solar System

Panel watts, battery Ah, controller amps — step by step.

LiFePO4 vs AGM Batteries

Which battery chemistry is right for your solar build?

MPPT vs PWM Controllers

Why MPPT is worth the extra cost in almost every system.

Series vs Parallel Wiring

How to wire solar panels and batteries for your system voltage.

Related Sizing Tools

WhatGeneratorSize.com

Size a gas or propane generator

DehumidifierPicker.com

Find the right dehumidifier size

WaterSoftenerSizer.com

Size a water softener by grain capacity

MattressSizer.com

Find the mattress size that fits your room

WhatPowerStation.com

Find the right portable power station

What Size Solar Panel Do I Need?

Quick Answer: What Solar Panel Size Do You Need?

Solar System Size Calculator

What are you powering?

Most Popular Solar System Configurations

EcoFlow Turnkey

DIY Mid-Range

DIY Budget

Solar Panel Size Quick Reference

Frequently Asked Questions

Size Solar for Your Use Case

Solar Sizing by Appliance

Recommended Solar Systems

Compare Solar Products

Solar Guides

Related Sizing Tools