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.
