How to Size Your Solar System
Build the Right Setup for Your Cabin, RV, Van, or Off-Grid Life
Sizing your solar system is one of the most important steps in creating a reliable, efficient off-grid setup. Whether you're powering a remote cabin, an RV adventure rig, or prepping for emergencies, the key is understanding how much energy you use and what components you’ll need to meet that demand — day or night.
At OutlandGrid, we make sizing simple. Here's what you need to know.
⚡ Step 1: Calculate Your Daily Energy Use
Start by making a list of everything you plan to power — lights, fridge, fans, devices, etc.
🔋 Example:
| Device | Watts | Hours/Day | Total Watt-Hours |
|---|---|---|---|
| LED Lights (4x) | 40W | 4 | 160 Wh |
| Laptop | 60W | 3 | 180 Wh |
| Mini Fridge | 100W | 8 | 800 Wh |
| Phone Charging (x2) | 10W | 2 | 20 Wh |
| Total | 1,160 Wh/day |
Tip: Add 20–30% as a buffer for cloudy days and system losses.
Final estimate: ~1,500 Wh/day
☀️ Step 2: Factor in Your Location’s Sunlight
Not all locations get the same amount of usable sun. Use your region’s peak sun hours (PSH) to determine how much energy your panels will generate.
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Example:
If you get 5 PSH per day, a 300W panel produces:300W × 5 hrs = 1,500 Wh/day
💡 The farther north you are, the fewer PSH you’ll have — especially in winter.
🔋 Step 3: Choose the Right Battery Capacity
Batteries store the energy your panels produce. You’ll want enough capacity to cover your daily usage plus at least 1–2 days of backup.
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For 1,500 Wh/day:
You’ll want at least a 1.5–2 kWh battery bank (i.e., a 100Ah 12V lithium battery = ~1,280 Wh)
Lithium batteries can be discharged nearly 100%. AGM or lead-acid should only be used down to ~50%.
⚙️ Step 4: Match Your Inverter Size (If Needed)
If you’re running AC appliances (like a microwave or TV), you’ll need an inverter to convert DC battery power to AC.
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Choose an inverter with more wattage than your highest single appliance draw.
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Add a little headroom — if your fridge uses 1,200W, get a 1,500–2,000W inverter.
🔄 Step 5: Make Sure Your Charge Controller Matches
Your charge controller regulates current from your solar panels to your batteries. Match the voltage and current rating to your panel output and battery bank.
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Use MPPT controllers for better efficiency, especially in low-light conditions or colder climates.
🧠 Summary: Sizing Checklist
✅ List all devices and estimate daily usage
✅ Check your location’s average peak sun hours
✅ Choose enough panels to generate your daily power needs
✅ Size your battery to match 1–2 days of backup
✅ Use the right inverter (if using AC loads)
✅ Match your charge controller to your system
🚀 Ready to Build Yours?
You don’t have to do this alone. Try our free Solar Kit Quiz to get a custom recommendation in under 60 seconds — or explore pre-built Off-Grid Kits designed for real-world use in cabins, vans, and tiny homes.
