Plan off-grid readiness for homes, sites, and cabins. Model sun hours, panel output, and batteries. Make confident choices before bids, permits, and installs begin.
| Daily Use (kWh/day) | PV Size (kW) | Sun Hours (h/day) | Derate (%) | Inverter (%) | Seasonal (%) | Battery (kWh) | Independence (%) | Autonomy (days) |
|---|---|---|---|---|---|---|---|---|
| 30 | 8 | 5 | 82 | 96 | 100 | 20 | ≈ 84 | ≈ 0.67 |
| 18 | 6 | 5.5 | 80 | 95 | 95 | 24 | ≈ 100 | ≈ 1.33 |
Grid independence starts with an accurate load profile. Use measured kWh from metering, not nameplate equipment lists. Split site demand into daytime production loads, evening lifestyle loads, and overnight essentials. This calculator works best when daily use reflects typical operation, not rare peaks. For projects, include lighting, pumps, compressors, IT, and temporary tools.
Solar production depends on peak sun hours and realistic losses. Derate captures module temperature, wiring, soiling, mismatch, and aging. Inverter efficiency converts DC to usable AC energy. The seasonal factor lets you stress-test winter months or monsoon periods. Enter conservative values to avoid optimistic sizing. If shading varies, use the worst month’s effective sun hours.
Batteries provide autonomy during low-sun windows and at night. Size storage using usable kWh, after depth-of-discharge limits and reserve margins. For construction sites, define critical loads first: safety lighting, communications, security, controls, and essential pumps. Noncritical loads can be scheduled to daylight. The calculator estimates autonomy days and shows extra storage needed for your target.
Independence here is an annual energy match: how much of yearly consumption can be supplied by expected solar production. A high percentage does not guarantee zero grid import, because timing matters. Short cloudy stretches can force imports unless storage or backup generation covers gaps. Use the daily surplus or deficit to judge whether load shifting or additional PV is the better lever.
Use the sizing outputs to compare scenarios before procurement. PV for target independence supports budget screening, while battery for target autonomy supports resilience goals. Validate results with local irradiance data, equipment specs, and permitted interconnection limits. Then refine with hourly modeling, roof or land layout, and contingency allowances for future load growth. Include contingency for panel degradation, future appliances, and maintenance downtime. For remote work, pair solar with a small generator as a last-resort safety net during extreme weather and fuel access.
It estimates annual energy match: expected yearly solar production divided by yearly consumption. It is capped at 100%. It does not automatically include time-of-day constraints or extended cloudy periods.
Solar generation and loads rarely align perfectly. Night demand, cloudy spells, and winter lows can cause shortfall. Batteries, load shifting, or backup generation may be needed to reduce imports.
Start with 75–85% for typical installations. Reduce it for hot climates, dust, shading, long wire runs, or older modules. Increase it only when design details and maintenance control losses reliably.
Use usable storage, not nameplate. Subtract reserve and depth-of-discharge limits. If the system keeps a backup buffer, exclude that portion so the autonomy result reflects energy you can actually use.
Use local solar resource data, installer reports, or PV modeling tools for your region. Prefer long-term averages, then apply a seasonal factor for the worst period you want to design around.
It provides a fast planning estimate. For full off-grid design, confirm hourly behavior, battery power limits, generator strategy, and safety margins. Validate with site shading, weather variability, and equipment specifications.
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.