Solar Panel Size Calculator for Off-Grid Cabins

Quick Answer

Off-grid cabins with a fridge, lights, laptop, TV, and kitchen loads use around 3.4 kWh/day, requiring 1100W of solar panels and a 650Ah battery at 24V for 3-day autonomy. The EcoFlow Delta 2 is the recommended all-in-one solution. A DIY 24V system with 3 400W panels and a 60A MPPT controller is the cost-optimized path for a permanent cabin install.

Pre-Calculated System Specs

Based on 5 peak sun hours, 3-day autonomy, and typical Off-Grid Cabin loads.

ComponentMinimum SizeNotes
Daily Load3.4 kWhRaw before system losses
Adjusted Load4.1 kWh+20% system loss buffer
Solar Panels1100W6x 200W or 3x 400W panels
Battery650Ah at 24VLiFePO4, 3-day autonomy (15.3 kWh total)
Charge Controller60A MPPTNEC 1.25x safety factor applied
Inverter3000W continuous2500W surge capacity, pure sine wave

Want to adjust for your exact appliances? Customize these numbers with our solar calculator

Recommended Turnkey Solution

EcoFlow Delta 2

2,048Wh capacity, 1,800W AC output — handles a fridge, TV, microwave, and most RV loads.

2,048Wh

Capacity

1,800W

AC Output

500W

Max Solar In

Buy on EcoFlow.comView Solar Bundle

DIY Component Approach

Prefer to build a custom system? Use these components matched to the calculated specs above. A DIY build typically costs 20-35% less than a turnkey power station for the same energy capacity.

Solar Panels

1100W total (6x 200W panels recommended)

Renogy 200W 12V Monocrystalline on Amazon

Battery

650Ah at 24V LiFePO4

LiTime 12V 200Ah LiFePO4 on Amazon

Charge Controller

60A MPPT minimum

Renogy 40A MPPT Rover on Amazon

Inverter

3000W pure sine wave

Renogy 2000W Pure Sine Wave Inverter on Amazon

Off-Grid Cabin Solar System Guide

Off-grid cabin solar systems are permanent installations designed for year-round or extended seasonal use. Unlike RV or van systems, cabin installations tolerate larger and heavier equipment because weight and mobility are not constraints. Ground-mounted solar arrays are common for cabins in forested areas where roof shading would limit rooftop output. A ground-mount tilted to the optimal angle for the cabin's latitude produces 15–25% more annual energy than a flat roof mount — a meaningful gain when designing for winter solar harvesting.

Battery bank sizing for cabin use prioritizes autonomy over weight. Most cabin builders target 3–5 days of energy storage without solar input to weather cloudy stretches. In regions with 5 peak sun hours, that means the battery bank stores 3–5x daily load, which translates to substantial capacity. LiFePO4 batteries at the cabin scale run $800–1,200 per 100Ah at 24V. The total battery investment for a well-designed cabin system is often $3,000–6,000, but the 10-year lifespan of LiFePO4 makes it cost-competitive with AGM over time.

Inverter-charger combos simplify cabin electrical systems significantly. A Victron MultiPlus or Schneider XW+ combines the inverter, battery charger, and automatic transfer switch in one unit. This means the cabin can charge its battery bank from a generator during prolonged cloudy periods without wiring a separate charger. The Victron MultiPlus-II 24/3000 is the most common choice for 24V cabin systems in the 2–4 kWh/day range, handling both regular cabin loads and the occasional high-draw appliance.

Frequently Asked Questions

What size solar system do I need for an off-grid cabin?▼
A cabin with a fridge, lights, laptop, TV, microwave, and coffee maker uses about 3,500–4,500Wh per day. With 5 peak sun hours, that requires 930–1,200W of solar panels. A standard cabin system runs on a 1,200W array (six 200W panels), a 200Ah 24V LiFePO4 battery bank, a 60A MPPT charge controller, and a 3,000W pure sine wave inverter. For year-round use with winter seasons, apply a 1.5x multiplier and size for 1,800W of panels.
How many batteries does an off-grid cabin need?▼
For 3 days of autonomy at 4,000Wh/day with LiFePO4 at 80% DoD, you need 15,000Wh of battery capacity — roughly a 625Ah 24V LiFePO4 bank. Most cabin builders achieve this with four 200Ah 24V LiFePO4 batteries (or eight 12V 200Ah in series-parallel). At current prices, expect $2,500–3,500 for that battery bank. Start with a 200Ah bank and expand as needed — LiFePO4 batteries can be added in parallel without the degradation concerns of AGM.
Can a cabin run entirely on solar in winter?▼
In the northern US (3–4 peak sun hours in December), a standard summer-sized system produces 40–60% less power than in July. Apply a 1.5x winter sizing multiplier to your panel array. A cabin that runs on 1,200W of panels in summer needs 1,800W for winter self-sufficiency. Additional winter load from electric blankets or a pellet stove's blower motor must also be factored. Propane backup heat and a propane or wood cook stove reduce the electrical load significantly for winter cabin use.
What voltage should a cabin solar system use?▼
24V is the right choice for most cabin systems in the 1–4 kWh/day range. At 24V, wire sizing requirements are half what they are at 12V for the same power, reducing cost on longer cable runs from roof to battery room. 48V becomes practical above 4 kWh/day or for arrays larger than 2,000W. Most quality inverter-chargers from Victron, Schneider, and Outback are available in both 24V and 48V configurations. 12V systems are practical up to about 600Ah — above that, cable gauge requirements become expensive.

Need a custom calculation?

The numbers above use typical off-grid cabin defaults. Adjust for your exact appliances and location.

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