Free Tiny House Solar Calculator
Calculate solar panel requirements, battery capacity, and inverter needs for off-grid living. Plan your energy system costs easily. Looking for complete systems? Browse our solar kits for tiny homes or explore our comprehensive off-grid solar power guide.
Free tiny house solar calculator • Updated November 2025
Steps to use the tiny house solar calculator:
- Enter Your Average Sun Hours
- Fill Out Load Calculator
- Calculate Tiny House Solar System Size
Important Safety Notice
This calculator provides estimates only. Always consult a licensed electrician and solar professional before designing or installing any electrical or solar system. Improper installation can cause fire, injury, or death. Ensure compliance with NEC 2023 and local building codes.
Step 1: Enter Your Average Sun Hours
Enter the average sun hours per day in your area during the darkest month (typically winter). You can find this data using the NREL PVWatts Calculator or by consulting with local solar installers.
How many Sun Hours a day do you average in the darkest month?
We'll use your winter low sun hours to size your PV array. Keep in mind your exact needs may vary depending on how your system will be used. Most locations in the US average between 3-6 hours in winter.
Step 2: Fill Out Load Calculator
Fill out the table below to estimate energy usage. We've included common household appliances found in off-grid homes. Try to account for everything, keeping in mind that off-grid homes should use efficient appliances, and the major heating loads (water & air heating) are usually not electric.
Solar Load Calculator
| Appliance | Quantity | Watts | Hours/Day | Wh/Day | Remove Appliance |
|---|
If you already have your monthly kWh total, you can enter it here:
Step 3: Calculate Off-Grid System Size
We'll estimate your off-grid system size based on the list of appliances and energy usage that you entered. Keep in mind that this is only an estimate, and there are many factors that can influence system sizing.
Click the "Calculate My System Size" button and we'll calculate your system size.
Frequently Asked Questions
How accurate is this calculator?
This calculator provides general estimates based on your inputs and typical off-grid system configurations. Actual requirements vary based on your specific appliances, usage patterns, climate, and local sun exposure. Always consult a licensed solar professional for final design and installation.
Why size for winter sun hours?
Winter typically has the lowest sun hours, so sizing your system for winter ensures you'll have adequate power year-round. During summer, you'll have excess capacity which helps extend battery life and handle unexpected loads.
What is battery autonomy?
Battery autonomy refers to how many days your battery bank can power your home without solar input. This calculator uses 3 days of autonomy, which is standard for off-grid systems to handle cloudy periods. You may want more in areas with frequent extended cloudy weather. Learn more about battery storage and system design.
Should I use all electric appliances?
No. Most successful off-grid homes use propane or wood for major heating loads (cooking, water heating, space heating). Heating with electricity requires very large (and expensive) solar and battery systems. Reserve electricity for lighting, electronics, and refrigeration. Check out our energy-efficient kitchen appliances and LED lighting options.
What about backup generators?
Many off-grid systems include a backup generator for extended cloudy periods or high-demand situations. A properly sized solar system should minimize generator use, but having one provides peace of mind and can reduce required battery bank size. Browse our recommended generators for tiny homes.
What's the cost of an off-grid system?
Off-grid solar systems typically cost $3-5 per watt installed, so a 5kW system would cost $15,000-$25,000. Batteries add $5,000-$15,000 depending on capacity and type. DIY installations can reduce costs by 30-50%, but require electrical knowledge and proper permitting.