ERC Solar PV Calculator

Size a solar PV system from energy use or monthly electric bill.

Estimate the solar array, panel quantity, and optional battery requirement using daily energy demand. You can start from monthly kWh consumption or from the amount paid using your electricity rate per kWh.

System Inputs

Enter your demand and adjust the design settings if needed.

Monthly kWh used Use this if you already know your monthly energy consumption. Monthly bill paid Use this if you know your total bill and your electricity price per kWh.

Monthly energy use (kWh)

Solar design settings

Peak sun hours

Performance ratio

Selected panel wattage

Target solar offset (%)

Panels per row

Panels per row is used to estimate clamp and mounting hardware quantities.

Electrical layout defaults

Roof type

Inverter type

Number of strings

Array to inverter distance (m)

Inverter to panel board distance (m)

These default values are used to refine string-based electrical quantities, PV wire length, and installation labor.

Include battery sizing

Pricing from Excel

Overhead (%)

Profit (%)

Contingency (%)

Discount (%)

VAT (%)

Upload pricing file (.xlsx, .xls, .csv)

No price file uploaded. Costing uses zero values until a template is uploaded.

Recommended solar PV size

3.75 kWp

Based on 15.00 kWh/day and full energy offset.

Energy summary

Monthly kWh 450.00 kWh

Daily kWh 15.00 kWh

Estimated panels 7 panels

Panel wattage used 550 W

Reference package Loading...

Battery recommendation

Battery bank needed Not enabled

Battery quantity 0 batteries

Per battery usable energy 0.00 kWh

Battery mode Grid-tied only

Mounting parts summary

Mid clamps 12 pcs

End clamps 8 pcs

Rail lines 4 rails

Roof attachments 28 pcs

Cable clips 14 pcs

Grounding lugs 2 pcs

Assumes 2 rails per row, 4 roof attachments per panel, 2 cable clips per panel, and 1 grounding lug per row.

Electrical parts summary

Inverter 1 pc

String count 2 strings

MC4 connectors 4 pairs

DC breaker / fuse 1 pc

AC breaker 1 pc

Combiner box 1 pc

PV wire 140 m

Installation labor 1 lot

Uses the selected string count, DC and AC run distances, roof type, and inverter type to estimate electrical quantities and labor.

Cost summary

Solar panels cost 0.00

Battery cost 0.00

Mounting hardware cost 0.00

Electrical parts cost 0.00

Direct cost 0.00

Overhead amount 0.00

Profit amount 0.00

Contingency amount 0.00

Discount amount 0.00

VAT amount 0.00

Final selling price 0.00

Upload the pricing template, then adjust overhead, profit, contingency, discount, and VAT to get your final selling price.

These values are planning estimates. Final solar PV and battery sizing should still be checked against the actual ERC standard you follow, site conditions, inverter design, load profile, and utility interconnection rules.