Turn your load profile into a right-sized system. See energy, equipment, and budget impacts instantly. Download results as CSV or a clean PDF report.
Daily kWh = sum(hourly kW × 1 hour)
PV size (kWdc) = (Daily kWh × Solar fraction)
÷ (PSH × Derate)
Panels (count) = ceil(PV size × 1000 ÷ Panel W)
Inverter (kW) = Peak kW × Surge factor
Battery (kWh) = (Daily kWh × Autonomy/24)
÷ (DoD × Battery efficiency)
Year‑1 savings = min(Annual PV kWh, Annual load kWh) × Rate
NPV = -Capex + Σ (Net cashflow_t ÷ (1+Discount)^t)
| Hour | Load (kW) | Hour | Load (kW) |
|---|---|---|---|
| 00:00 | 0.60 | 12:00 | 0.90 |
| 01:00 | 0.50 | 13:00 | 1.00 |
| 02:00 | 0.50 | 14:00 | 1.10 |
| 03:00 | 0.50 | 15:00 | 1.30 |
| 04:00 | 0.60 | 16:00 | 1.80 |
| 05:00 | 0.80 | 17:00 | 2.20 |
| 06:00 | 1.20 | 18:00 | 2.40 |
| 07:00 | 1.60 | 19:00 | 2.00 |
| 08:00 | 1.40 | 20:00 | 1.60 |
| 09:00 | 1.20 | 21:00 | 1.20 |
| 10:00 | 1.00 | 22:00 | 0.90 |
| 11:00 | 0.90 | 23:00 | 0.70 |
Hourly demand data turns “average use” into actionable design values. A home using 30 kWh/day might peak at 2 kW or 7 kW depending on cooking, pumps, or air‑conditioning. The calculator converts 24 hourly kW entries into daily energy and peak demand, then sizes the inverter with a surge factor. This prevents undersized inverters that trip, and oversized units that add cost. For commercial sites, capturing 15‑minute interval peaks can reveal demand charges and justify higher inverter headroom early too.
PV capacity is computed from target daily kWh, peak sun hours, and system derate. Typical derate values range from 0.70 to 0.85 to reflect temperature, wiring, mismatch, and soiling. If PSH drops from 5.5 to 4.5, the required kWdc increases by about 22% for the same energy target, so local solar resource matters as much as load.
Not every project must offset 100% of annual usage. Setting a 60–80% solar fraction can reduce array size while still capturing the best economics in high‑tariff tiers. The calculator also caps annual offset at annual load, so savings don’t assume unrealistic overproduction. Use the fraction to model phased expansions as budgets allow.
For off‑grid or hybrid designs, storage is calculated from an autonomy window, depth of discharge, and round‑trip efficiency. For example, 10 kWh needed overnight with 80% DoD and 90% efficiency implies about 13.9 kWh of installed battery. The tool also converts kWh to amp‑hours using your selected bank voltage for quick string planning.
Year‑1 savings are estimated from the smaller of PV production and annual load, multiplied by your rate. O&M is modeled as a percent of total capex, and escalation and discounting produce NPV. A positive NPV indicates value versus the discount benchmark, while IRR approximates the break‑even rate. Payback remains a simple checkpoint, not a full profitability measure.
A load profile is hourly power demand across a day. It reveals peaks that drive inverter sizing and helps convert “daily kWh” into realistic system requirements.
Use long‑term averages for your location and tilt. Many sites fall between 3.5 and 6.5 hours. If you are unsure, choose a conservative value to avoid undersizing.
Derate bundles real‑world losses from temperature, wiring, inverter conversion, and soiling. A common planning range is 0.70–0.85, depending on climate and maintenance.
Motors and compressors can draw short surge currents. The surge factor adds headroom so the inverter can start these loads without voltage sag or shutdown.
Add batteries when you need backup, nighttime operation, or off‑grid autonomy. Grid‑tied projects focused on bill savings often skip storage to lower upfront cost.
Any currency works as long as you keep it consistent for costs and electricity rate. Results will follow the same units for savings, capex, and NPV.
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.