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Home Battery Calculator

The home battery calculator helps you size a battery storage system for your home. Enter your daily energy consumption, the desired number of autonomy days and the depth of discharge (DoD), and the calculator will instantly show you the required nominal capacity and estimated installation cost.

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How to use the calculator?

1. Enter your daily energy consumption in kWh (check your utility bill or smart meter). 2. Set the number of autonomy days — how many days you want to run without the grid or sunlight. 3. Set the depth of discharge (DoD) according to your battery specification (typically 80%). 4. The calculator instantly shows the required nominal capacity and approximate cost.

Calculation example

A household uses 10 kWh per day and wants 2 days of autonomy at 80% DoD. Usable capacity needed: 10 × 2 = 20 kWh. Nominal capacity: 20 / 0.80 = 25 kWh. Estimated cost: 25 × 2000 = 50,000 PLN.

Frequently asked questions

What is a home battery?

A home battery is an energy storage device that lets you store electricity from solar panels or the grid and use it on demand, increasing your energy independence.

How do I calculate the required battery capacity?

Multiply your daily consumption by the number of autonomy days, then divide by the depth of discharge (DoD). The calculator does this automatically.

What does DoD mean?

DoD (Depth of Discharge) is the percentage of battery capacity you can safely use. At 80% DoD, a 10 kWh battery provides 8 kWh of usable energy.

A rough estimate is around 2,000 PLN per kWh of nominal capacity, including equipment and installation. Prices vary by brand and technology.

For everyday use, 1–2 days is sufficient. For greater independence during winter or grid outages, consider 3–5 days.

LFP (lithium iron phosphate) batteries offer long cycle life and high safety, making them the recommended choice for residential storage.

It can be used for time-of-use arbitrage — charging at cheap off-peak rates — but payback periods are much longer without PV.

The calculator provides indicative values. Precise sizing requires an energy audit and consultation with a certified installer.

Modern LFP batteries last 4,000–6,000 cycles, equivalent to 10–15 years of daily use.

In Poland, programmes such as Mój Prąd and NFOŚiGW grants cover energy storage. Check current conditions on the relevant authority websites.

Results are for indicative purposes only and do not constitute a commercial offer. Actual cost and battery sizing depend on the manufacturer, technology, local labour rates and available subsidies.

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