Aienginear · Energy engineering tools

Electricity, Solar & AC Savings Calculator

v2.0.0 · appliance kWh · slab tariffs · PV yield & ROI (NPV, IRR, LCOE) · AC EER/SEER/CSPF

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Region example Currency symbol Grid CO₂ factor (kg/kWh) Example values are illustrative only — replace with your own bill, tariff and installer quote.

1Appliances

Appliance	Power (W)	Qty	Hours/day	Duty %	Days/month	kWh/month

Duty % is the share of running time the appliance actually draws its rated power (e.g. a refrigerator compressor ≈ 35–50 %, a fixed-speed AC ≈ 60–80 % in hot weather). Use the nameplate or measured watts.

2Tariff

     Tariff type
     Energy rate per kWh
     Fixed / meter charge per month
     Taxes & duties (%)
    

Results

–kWh per day

–kWh per month

–Monthly bill

–Annual cost

–Effective rate / kWh

–CO₂ per year

Where the energy goes

1System size & site

     Sizing method
     Target offset of annual use (%)
     System size (kWp DC)
     Location (peak sun hours)
     Peak sun hours (kWh/m²·day, plane of array)
     Performance ratio PR
     Degradation (%/year)
     Module rating (Wp)
     Module area (m²)
    

PR (performance ratio, IEC 61724-1) bundles temperature, soiling, wiring, mismatch, inverter and availability losses. 0.75–0.85 is typical for a well-installed grid-tied rooftop; hot dusty sites sit at the lower end.

2Costs & tariff

     Installed cost per kWp
     Subsidy / incentive (%)
     Avoided tariff per kWh
     Export (buy-back) rate per kWh
     Self-consumption (%)
     Tariff escalation (%/year)
     O&M (% of capex/year)
     Inverter replacement (% capex, yr 12)
     Discount rate (%)
     Analysis life (years)
    

Results

–System size

–Modules / array area

–Year-1 generation

–Specific yield

–Net investment

–Year-1 savings

–Simple payback

–Discounted payback

–NPV

–IRR

–LCOE per kWh

–CO₂ avoided / year

Cumulative cash flow

Year-by-year cash flow

1Cooling duty

     Capacity
     Unit
     Number of units
     Hours per day
     Cooling days per year
     Average load factor (%)
    

2Efficiency: existing vs new

     Existing — metric
     Existing — value
     New — metric
     New — value
    

     Current thermostat (°C)
     New thermostat (°C)
     Saving per °C raised (%)
     Tariff per kWh
     New AC price per unit
    

EER and SEER/SEER2 are in BTU/Wh (AHRI 210/240). COP, CSPF (ISO 16358-1), ISEER and EU SEER are in W/W. 1 W/W = 3.412 BTU/Wh. Seasonal metrics already include part-load behaviour, so they are the better basis for inverter units.

Results

–Cooling capacity (kW)

–Existing input (by metric)

–New input (by metric)

–Existing kWh / year

–New kWh / year (with setpoint)

–Energy saved

–Money saved / year

–Payback on new AC

Electricity, Solar & AC Savings Calculator

1Appliances

2Tariff

Results

Where the energy goes

1System size & site

2Costs & tariff

Results

Cumulative cash flow

1Cooling duty

2Efficiency: existing vs new

Results

Savings breakdown

Your energy report

Self-test (calculation engine)