How do I calculate what size solar battery I need?

You can calculate your required battery capacity by determining your total nightly or backup power consumption (in kWh) and dividing it by the battery's depth of discharge (DoD). For example, lithium batteries can typically discharge up to 90%, whereas lead-acid batteries should only be discharged to 50%.

Is it worth getting a solar battery?

Yes, if you want to use your solar energy at night, protect yourself from power outages, or if your local utility offers low export rates and high import rates. A battery helps you maximize self-consumption.

Solar Battery Capacity Calculator | Size Your Battery Storage

Select your appliances

Click to add — tap again to remove

0 appliances selected · Daily load: 0.00 kWh

Configure Load Details

No appliances added yet

Click items in the grid above to add them to your solar estimation plan.

Awaiting Configuration

Select your appliances above to see your personalised solar recommendation.

Step-by-Step Guide

How to Use the Solar Calculator

Follow these three steps to accurately size your solar power system for home or business use.

Calculate Total Consumption

Before purchasing solar panels, you must know your actual daily consumption in kilowatt-hours (kWh). Our solar panel calculator allows you to input exact quantities, power ratings (Watts), and daily operating hours for fans, LED lights, air conditioners, and kitchen appliances.

(Watts × Qty × Hours) ÷ 1000 = kWh per day

Grouping appliances gives your total daily and monthly utility footprint.

Recommended Solar System Size

System size in kW depends on average daily sun hours and efficiency losses. Average global locations receive between 4.0 to 6.0 peak sun hours per day. We assume a standard 5.0 peak sun hours with an 80% system efficiency factor.

Daily kWh ÷ (Peak Sun Hours × 0.8) = Solar kW Size

We automatically round up to align with whole numbers of modern 550W modules.

Select Inverter & Batteries

Inverters convert DC solar panel power to AC home power. We apply a 20% safety headroom above the system size. For energy storage, we calculate backup requirements during night-time or power outages based on your backup hours target.

Lithium: 85% DoD • Lead-Acid: 50% DoD

Lead-acid batteries must align with series voltage connection multiples (4× for 48V systems).

Common Questions

Solar Panel FAQs — Germany

What size inverter is recommended for a solar system?

Which battery chemistry should I choose for solar backup?

How many lead-acid batteries are needed for a 48V solar inverter?

Does roof orientation affect solar panel output?

Should I get a battery with my solar panels?

It depends on your usage pattern. If you're home during the day, you'll self-consume most solar directly and a battery adds modest value. If you're out during peak generation hours (9am–3pm), a battery captures that generation for evening use and can cut your bill by an extra 20–30%. In countries with low feed-in tariffs (like Germany post-2024), batteries make more financial sense than exporting cheaply.

Can I use solar panels to charge my electric car at home?

What is Einspeisevergütung and how much can I earn?

Do I need to register my solar system in Germany?

Are solar panels VAT-free in Germany?

Solar Battery Capacity Calculator

Free Solar Panel Calculator

Select your region

How do you want to calculate?

Setup options