Calculator Input
Example Data Table
| Panel W | Panels | Sun Hours | Loss % | Inverter % | Daily Load | Estimated Output |
|---|---|---|---|---|---|---|
| 450 | 12 | 5.2 | 14 | 96 | 20.00 kWh | 23.19 kWh/day |
| 550 | 8 | 4.8 | 16 | 95 | 18.00 kWh | 16.85 kWh/day |
| 400 | 16 | 5.7 | 12 | 97 | 25.00 kWh | 31.18 kWh/day |
Formula Used
Appliance load: watts × quantity × hours ÷ 1000.
DC array size: panel watts × panel count ÷ 1000.
Daily AC output: array kW × peak sun hours × derate factor × inverter efficiency.
Total daily demand: known daily usage + appliance load estimate.
Coverage: daily AC output ÷ total daily demand × 100.
Battery storage: daily demand × autonomy days ÷ depth of discharge ÷ battery efficiency.
Battery amp hours: battery kWh × 1000 ÷ system voltage.
Recommended inverter size: peak load watts × 1.25.
How to Use This Calculator
- Enter each panel wattage and the total panel count.
- Add local peak sun hours for an average day.
- Enter expected system loss and inverter efficiency.
- Add your known daily usage in kWh.
- Use the load builder for appliances and equipment.
- Enter battery, voltage, cost, and emissions values.
- Press the calculate button to view results above the form.
- Download CSV or PDF results for records.
Solar Power Usage Planning
Overview
A solar panel system is more useful when the load is known. The panel rating alone does not show real usable energy. Sun hours, losses, batteries, and demand all change the final result. This calculator connects those details in one place. It helps you compare panel output against daily power use. It also shows when a system may be undersized or oversized.
Why Power Usage Matters
Electrical loads draw energy over time. A 500 watt load running for two hours uses 1 kWh. Solar panels produce energy only when sunlight is available. Their output also falls because of heat, wiring loss, dust, shading, and inverter conversion. For that reason, a 1 kW array rarely gives 1 kW all day. Planning with loss factors gives a safer estimate. It can reduce weak battery performance and poor backup time.
Sizing Panels and Batteries
Panel sizing starts with daily usage. Divide the needed daily kWh by sun hours and total efficiency. The answer gives the required array size. Then divide array size by panel wattage. Battery sizing uses the same daily load, but adds autonomy days. Depth of discharge protects battery life. Battery efficiency accounts for charge and discharge loss. The result is shown in kWh and amp hours. This makes it easier to match battery banks.
Cost and Environmental Value
Solar usage planning also supports budget choices. The calculator estimates bill savings from covered energy. It uses your electricity rate for that step. It also estimates avoided emissions using a carbon factor. These values are planning estimates, not guarantees. Weather, tariff rules, panel age, and roof layout can change results. Still, the estimate gives a useful first direction before detailed design.
Practical Design Notes
Use realistic sun hours for your location. Enter lower values for cloudy seasons. Increase derate loss when panels face heat, dust, or shade. Enter peak load to size the inverter with a margin. Check local rules before connecting any system to a building. A licensed electrician should verify wiring, breakers, grounding, and safety equipment. Good planning improves reliability and protects equipment. Keep records of assumptions. Review them after installation. Actual meter data can refine future panel, battery, and load decisions over time with confidence.
FAQs
What does this calculator estimate?
It estimates solar panel output, daily demand, battery size, inverter size, savings, and emissions reduction using your entered electrical values.
What are peak sun hours?
Peak sun hours describe usable solar strength during a day. They are not the same as total daylight hours.
Why is derate loss included?
Derate loss covers real system reductions from heat, wiring, dust, shading, mismatch, and other practical conditions.
Why is AC output lower than panel rating?
Panel rating is measured under test conditions. Real output falls after losses and inverter conversion.
Can this calculator size batteries?
Yes. It estimates battery kWh and amp hours using daily demand, autonomy days, discharge depth, efficiency, and voltage.
Should I include appliance loads?
Use appliance loads when you do not know exact daily usage. They help build a practical demand estimate.
Is the inverter recommendation final?
No. It is a planning value with margin. Surge loads and electrical codes may require a different inverter.
Can I export the results?
Yes. Use the CSV button for spreadsheet records or the PDF button for a simple report.