Solar Demand Input Form
Enter load, sunlight, losses, storage, and inverter assumptions. The calculator sizes array demand, backup storage, inverter rating, and roof use.
Example Data Table
| Scenario | Daily Use | Sun Hours | Losses | Panel Size | Autonomy | Array Need |
|---|---|---|---|---|---|---|
| Small workshop | 12 kWh | 5.8 | 16% | 450 W | 1 day | 2.46 kW |
| Farm pump room | 24 kWh | 5.2 | 18% | 550 W | 1.5 days | 5.63 kW |
| Remote site cabin | 8 kWh | 4.7 | 20% | 400 W | 2 days | 2.13 kW |
Formula Used
These relationships estimate practical array size, stored energy, and inverter headroom after accounting for losses, backup expectations, and usable battery capacity.
How to Use This Calculator
- Enter your total daily electrical demand in kilowatt-hours.
- Add average peak sun hours for the installation location.
- Choose a panel wattage that matches your preferred module.
- Estimate wiring, temperature, dust, and conversion losses.
- Set battery autonomy and depth of discharge limits.
- Enter battery voltage, inverter efficiency, and simultaneous AC load.
- Review the result cards above the form after submission.
- Export results to CSV or PDF for planning records.
Why Solar Demand Sizing Matters
Solar demand sizing connects daily electrical needs with available sunlight, real equipment losses, and practical storage limits. A rough estimate often understates inverter margin, battery reserve, or physical space. This calculator converts engineering assumptions into usable planning numbers.
Daily energy demand is the foundation. Loads such as motors, pumps, fans, refrigeration, and electronics define how much energy the array must replace. If the target is full solar coverage, the system must produce nearly all daily consumption over the design period.
Peak sun hours turn location data into production potential. Higher sun hours reduce array size, while cloudy regions require more installed capacity. Losses from temperature, cabling, soiling, mismatch, and inverter conversion also reduce useful output, so they must be included early.
Battery planning depends on autonomy expectations. One site may need only evening coverage, while another may need full-day backup during poor weather. Depth of discharge affects battery life and usable energy, so the nominal battery bank must exceed the energy you expect to withdraw.
Inverter sizing should reflect the maximum simultaneous AC load, not just daily energy. Equipment with start-up surges can temporarily exceed steady-state demand, so a surge factor gives safer headroom. Ignoring this can cause nuisance trips or unstable performance during peak operation.
Roof area is another engineering check. A design may meet electrical demand but fail spatially if the available mounting surface is small. By estimating module area and comparing coverage, this calculator shows whether the proposed array can physically fit the project site.
FAQs
1. What does solar demand mean here?
It means the solar array, storage, and inverter capacity needed to satisfy your chosen share of daily electrical consumption under stated operating assumptions.
2. Why are peak sun hours important?
Peak sun hours convert solar resource quality into expected daily production. Lower sun hours require larger array capacity to deliver the same daily energy.
3. Should I include system losses?
Yes. Temperature, dust, wiring, shading, inverter conversion, and module mismatch all reduce delivered energy. Ignoring losses usually undersizes the array.
4. What is battery autonomy?
Battery autonomy is the number of days the battery should support demand when solar generation is weak or unavailable.
5. Why does inverter size differ from daily energy?
Daily energy measures consumption over time. Inverter size handles instantaneous power. High simultaneous loads or motor starts can require larger inverter capacity.
6. Can this calculator check roof fit?
Yes. It multiplies recommended module count by panel area and compares the required area with your available roof space.
7. Are these results final design values?
No. They are planning estimates. Final engineering should include site survey, wiring design, structural review, protection devices, and local code requirements.