Estimate off grid solar budgets from daily energy loads. Review panels, batteries, and balance costs. See clearer project economics before purchasing critical system components.
The form uses a three column layout on large screens, two on smaller screens, and one on mobile.
| Input | Example Value |
|---|---|
| Daily energy use | 12,000 Wh/day |
| Peak load | 3,500 W |
| Sun hours | 5.5 h/day |
| Autonomy | 2 days |
| Panel rating | 550 W |
| Battery module | 5.12 kWh |
| Battery voltage | 48 V |
| Contingency | 8% |
| Output | Illustrative Result |
|---|---|
| Installed array | 3,850 W to 4,950 W range |
| Battery storage | 30 kWh to 35 kWh range |
| Inverter sizing | 4,375 W minimum |
| Controllers | 1 unit at 100 A |
| Panels needed | 7 to 9 modules |
| Batteries needed | 6 to 7 modules |
| Total budget | Depends on local pricing assumptions |
| Cost per watt | Useful for comparing design options |
Corrected Daily Wh = Daily Load Wh ÷ Inverter Efficiency
Base Array W = Corrected Daily Wh ÷ (Sun Hours × Array Derate)
Recommended Array W = Base Array W × (1 + Seasonal Oversize)
Battery Storage Wh = (Corrected Daily Wh × Autonomy Days) ÷ (Battery DoD × Battery Efficiency)
Battery Bank Ah = Battery Storage Wh ÷ Battery Voltage
Required Inverter W = Peak Load W × Surge Factor
Controller Current A = Installed Array W ÷ Battery Voltage
Total Cost = Equipment Costs + Soft Costs + Contingency
Enter your total daily energy use and highest expected simultaneous watt demand.
Add local sun hours, autonomy days, and efficiency assumptions for realistic sizing.
Fill in panel, battery, inverter, controller, and balance of system costs.
Submit the form, review sizing and costs, then export results as CSV or PDF.
It estimates off grid solar array size, battery storage, inverter capacity, controller requirements, and the full project budget. It also includes soft costs such as labor, wiring, permits, and contingency so you can compare realistic design options.
Daily energy use measures total consumption across the day. Peak load measures how much power is needed at the same moment. Batteries are influenced by energy needs, while inverter sizing depends more heavily on peak demand and surge conditions.
Real systems lose energy from heat, cable resistance, dust, aging, mismatch, controller conversion, and other operating conditions. Derating lowers theoretical production so your recommended array better reflects practical field performance.
Battery autonomy is how many days the system can support loads without significant solar charging. Higher autonomy improves resilience during poor weather, but it usually raises battery count, storage cost, and total system budget.
Use the maximum depth of discharge recommended by the battery manufacturer, not a guess. Lithium systems often tolerate deeper discharge than lead acid systems. Conservative values usually improve cycle life and reduce replacement frequency.
No generator cost is added by default. You can include it under miscellaneous cost or adjust contingency if your project includes backup generation, transfer gear, fuel storage, or service access infrastructure.
Contingency helps absorb price changes, forgotten components, shipping variations, and on site surprises. It makes the budget more robust, especially during early planning when design details and local contractor pricing may still change.
It is a planning tool, not a stamped engineering package. Before procurement, confirm electrical design, climate assumptions, cable sizing, battery chemistry, structural support, safety devices, and local code requirements with a qualified professional.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.