Example Data Table
| Appliance |
Watts |
Hours per day |
Quantity |
Daily Wh |
| LED lights |
12 |
5 |
8 |
480 |
| Ceiling fan |
60 |
8 |
2 |
960 |
| Refrigerator |
150 |
10 |
1 |
1500 |
| Laptop |
65 |
6 |
2 |
780 |
| Water pump |
750 |
1 |
1 |
750 |
Formula Used
Daily energy: watts × hours × quantity.
Required solar array: daily Wh ÷ peak sun hours ÷ performance factor.
Panel count: required array watts ÷ panel watts, rounded up.
Daily production: installed watts × sun hours × performance factor ÷ 1000.
Battery Wh: daily Wh × autonomy days ÷ depth of discharge ÷ battery efficiency.
Battery Ah: battery Wh ÷ system voltage.
Inverter rating: peak load ÷ inverter efficiency.
Surge rating: peak load × surge factor.
Controller amps: array watts ÷ system voltage × safety margin.
Voltage drop: current × conductor resistance.
Wire resistance: resistivity × two way length ÷ cable area.
Payback: total project cost ÷ annual energy saving.
How to Use This Calculator
Enter each appliance on a separate line. Use this order: name, watts, hours, and quantity.
Enter the local peak sun hours. Use a conservative seasonal value for safer design.
Add losses for dust, heat, aging, wiring, controller loss, and shading.
Choose system voltage, panel rating, battery settings, and cable details.
Enter cost values when you need a payback estimate.
Press the calculate button. Review the result table above the form.
Use CSV or PDF export to save the project report.
Solar Panel Project Planning
A solar panel project starts with real energy demand. Guessing usually creates weak systems. This calculator uses a load schedule, sun hours, losses, storage goals, and cost values. It then turns those values into practical project sizes. The result helps you compare panel count, battery bank size, inverter size, controller rating, voltage drop, and payback.
Why System Sizing Matters
Every solar design must balance production and use. A small array may fail during cloudy weeks. An oversized array may waste money. Batteries also need careful sizing. Deep discharge shortens battery life. Low inverter capacity causes trips during starting loads. Wiring that is too small creates heat and voltage loss. Good planning reduces these problems before any parts are purchased.
Main Design Factors
Daily energy use is the starting point. It may come from the appliance table or from a direct kWh entry. Peak load decides the inverter. Local peak sun hours decide array size. Loss percentage covers dust, heat, wiring, controller loss, mismatch, and aging. Autonomy days set how long the battery should support loads without useful sun. Depth of discharge protects the battery. The cable values estimate voltage drop along the round trip path.
Cost And Performance Review
The calculator also estimates project cost. It adds panel, battery, inverter, controller, mounting, wiring, and other costs. Monthly production is compared with your energy price. This gives a simple annual saving and payback period. The carbon estimate uses the grid emission factor. It is only an estimate, but it helps compare project scale.
Using Results Wisely
Use the output as an early design guide. Confirm local codes, roof structure, breaker ratings, grounding, and protection devices. Solar equipment must match voltage, current, and temperature limits. A licensed installer or qualified electrician should review final wiring and safety choices. Change one input at a time. Compare scenarios with different panel watts, battery depth, or sun hours. Export the report when you need a record for planning or discussion.
Common Scenario Checks
Try a summer case and a winter case. Save both reports. The difference shows seasonal risk. Also test a lower battery depth. This can improve life. Finally, review voltage drop with longer cable runs before choosing wire carefully.
FAQs
What does this solar project calculator estimate?
It estimates panel count, array capacity, battery storage, inverter rating, controller amps, voltage drop, roof area, cost, savings, and payback.
Can I use appliance data instead of daily kWh?
Yes. Enter each appliance line with name, watts, hours, and quantity. The calculator will use the schedule first.
What are peak sun hours?
Peak sun hours convert local sunlight into useful full power hours. Lower values create more conservative solar designs.
Why should I include system losses?
Losses cover dust, heat, shading, wiring, controller loss, mismatch, and age. Real systems rarely produce perfect rated output.
How is battery size calculated?
Battery size uses daily energy, autonomy days, depth of discharge, and battery efficiency. More autonomy increases storage needs.
What does voltage drop mean?
Voltage drop is lost voltage in the cable. High drop reduces performance and may create heat in long wire runs.
Is the payback result exact?
No. It is a simple estimate. Actual savings depend on tariffs, weather, equipment quality, maintenance, and local rules.
Should an electrician review the final design?
Yes. Final solar wiring, breakers, grounding, disconnects, and protection devices should be checked by a qualified professional.