Battery storage: how many kWh to avoid peak hours?
Batteries charge during off-peak hours or from surplus solar power and discharge during EVN peak hours, 5:30 p.m.–10:30 p.m. Enter your peak-hour load — the calculator returns capacity, power, number of containers and savings under the EVN tariff.
What the model calculates, and what it doesn't
Pin discharge during EVN peak hours (5:30 p.m.–10:30 p.m., Monday–Saturday) and charge off-peak hours (00:00–06:00) or from surplus daytime solar power. Discharged energy = peak load × share to be covered × 5 hours. Nominal capacity is the greater of the energy to discharge ÷ usable fraction and the power to discharge ÷ C-rate. Savings = discharged energy × peak price − energy charged from the grid × off-peak price, per the EVN tariff.
Not calculated: battery degradation by year, operating and insurance costs, fire protection, connection fees, and reduced peak capacity in the power purchase agreement. Unit investment cost is entered by you from your quote — the tool does not assume battery prices.
Frequently asked questions
Where do the savings from storage batteries come from?
From the electricity price spread. Under the current EVN tariff, the peak rate is nearly three times the off-peak rate. Batteries charge when power is cheap and discharge when it is expensive; each cycle loses about 10–15% to charge–discharge losses.
Why should you combine batteries with solar power?
EVN peak hours are currently 5:30 p.m.–10:30 p.m., when there is no sunshine, so solar power alone cannot reduce peak-hour charges. Batteries store surplus daytime solar power to discharge in the evening — that charging energy is almost free.
C-rate 0,5C hay 0,25C?
0.5C fully discharges in about 2 hours, 0.25C in about 4 hours. Peak hours last 5 hours, so if the battery must cover the load for all 5 hours, capacity is set by energy; C-rate only becomes the constraint when peak load is large relative to capacity.
Have real project parameters? Send them to CGD and get feedback on the design scope
This simulation stops at the principle. For a specific project, CGD builds the model on real operating data and floor plan drawings.
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