Model time-based tariffs, solar generation, and storage impacts today. See baseline bills versus solar bills. Export credits and peak shaving are included for decisions.
Use this example to sanity-check your entries and understand outputs.
| Scenario | Load (kWh) | Solar (kWh) | Peak rate | Off-peak rate | Self-consumption | Battery (kWh) |
|---|---|---|---|---|---|---|
| Small site office | 900 | 650 | 55 | 30 | 60% | 8 |
| Site accommodation | 1400 | 900 | 62 | 34 | 55% | 12 |
| Tools and workshop | 2200 | 1200 | 70 | 38 | 50% | 15 |
Construction projects often face variable tariffs where peak windows carry the highest unit cost. This calculator separates monthly kWh into peak, shoulder, and off-peak shares, then applies the correct rate to each block. When peak pricing is high, even modest peak reduction can materially lower the total bill. Use the fixed charge field to capture meter fees so comparisons remain realistic.
Solar generation is rarely uniform across tariff periods. By assigning solar kWh into the same three periods, the tool estimates how much PV coincides with daytime activity versus late or early hours. The direct-use calculation is limited by both period load and period solar. This avoids overcrediting PV during times when the site is lightly loaded.
Battery capacity shifts surplus solar into expensive periods, but losses reduce delivered energy. Round-trip efficiency is applied to the charged energy to estimate usable discharge. Dispatch priority lets you offset peak first for maximum savings, or shoulder first if your tariff design makes that period costly. Optional off-peak grid charging can model simple arbitrage where permitted.
Any solar not used directly or stored is treated as export and credited at the export rate. The net energy charge equals the cost of remaining grid imports minus export credits. Demand charges can be added when the utility bills by monthly peak kW. The reduction percentage provides a practical estimate of peak shaving from PV and storage.
Use the baseline and “with solar” totals to benchmark procurement options, generator run-time strategies, and PV sizing. Review the period table to identify which time block drives costs, then adjust load scheduling or battery capacity accordingly. Export CSV for estimators and PDF for approvals, ensuring assumptions remain transparent and traceable. For early estimates, run multiple scenarios to bracket uncertainty and document the chosen basis of design clearly.
It is a pricing structure where the unit rate changes by time window. Peak periods usually cost more, while off-peak periods cost less. The calculator applies a separate rate to each period’s kWh.
Start with site operating hours and major loads. Metering data is best. If unavailable, estimate how much energy occurs during daytime work, evenings, and nights, then adjust so the three percentages sum to 100%.
Self-consumption limits how much solar is assumed to be used onsite. Lower targets increase exports, which may be credited at a lower rate than imports. Higher targets represent better load matching or effective storage.
Charged energy is multiplied by round-trip efficiency to estimate delivered discharge. For example, 10 kWh charged at 90% efficiency yields about 9 kWh available to offset imports. This accounts for conversion and storage losses.
Yes. Enable demand charges, enter the baseline monthly peak kW and the demand rate. Then enter an estimated reduction percentage to approximate peak shaving effects from PV and storage.
Not always. Many tariffs credit exports at a separate, often lower rate. Enter the export credit from your interconnection or net billing agreement so the model reflects your actual billing rules.
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.