Home battery: price, subsidies and earnings explained

The price of a home battery depends on capacity, power rating, brand and installation, and the market moves quickly — so always get specific quotes rather than trusting average figures. The most important thing to understand before buying is the income side: a modern home battery can generate income or savings in three ways — higher self-consumption of your own solar power, buy-cheap-use-expensive trading on the spot market, and ancillary services for Energinet. The last leg is the most overlooked, and it is also where the battery’s greatest technical strength lies: it reacts within seconds.

What does a home battery cost?

There is no single price. The total cost depends on:

• Capacity (kWh): how much energy the battery can store. More capacity costs more, but also gives you more to work with.
• Power rating (kW): how quickly the battery can charge and discharge. The rating determines how much it can move in a short time.
• Brand and chemistry: manufacturers compete on price, warranty and software, and the price level changes continuously.
• Installation: whether the battery can connect to an existing inverter, or whether a new inverter and electrician work are needed.

Lifetime and warranty

A battery’s lifetime is typically stated in charge cycles and calendar years, and manufacturers guarantee that a certain share of capacity remains at the end of the warranty period. Read the warranty terms carefully: some warranties set conditions for how the battery may be used. Professional control — including when the battery delivers ancillary services — stays within the manufacturer’s limits — always check the warranty terms.

Subsidies and tax rules

The rules on subsidies, taxes and metering schemes change from time to time, and they depend on your specific situation — including whether the battery is installed together with a solar PV system. Check the current rules with the authorities before running the numbers, and ask your installer to document what applies to your particular installation.

The battery’s three income legs

1. Higher self-consumption of solar power. If you have solar panels, they produce the most in the middle of the day, when you may not be home. Without a battery, you sell the surplus cheaply and buy power back expensively in the evening. The battery stores the midday power for the evening’s consumption, so a larger share of your own production is used by you.
2. Spot arbitrage: charge cheap, use expensive. Electricity prices are set hour by hour on Nord Pool and are typically low at night and high at the evening peak. The battery can charge in the cheap hours and cover the house’s consumption in the expensive ones. How the hourly prices come about is explained in our article on electricity prices hour by hour.
3. Ancillary services for Energinet. The grid must constantly hold the frequency at 50 Hz, and Energinet buys reserves such as FCR-D in daily auctions — one for every hour of the day. Batteries are the fastest reserve on the grid, which is exactly why they are well suited to the task. A single household’s battery is too small to participate alone, but through an aggregator it joins a virtual power plant together with many others. The background is explained in our article on grid balancing.

The three legs behave differently: self-consumption and arbitrage are savings on your electricity bill, while ancillary services are an actual income paid out to you. How much each leg contributes depends on your consumption, your solar system if you have one, and market prices — and FCR-D prices are set in daily auctions and vary. Historical earnings are no guarantee of future earnings.

Can the three legs be combined?

Yes — and this is where intelligent control makes the difference. A battery that only optimises self-consumption leaves capacity idle for large parts of the day. Professional control can bid the battery into the FCR-D auctions while still accounting for solar production and spot prices, so the legs complement each other instead of getting in each other’s way. It does require that the control system knows the market: the auctions are decided the day before, hour by hour, and the battery must deliver what has been promised. That coordination is what an aggregator does.

How NM1 connects your battery

NM1 connects your home battery to the virtual power plant. The integration runs through the inverter manufacturers (including Solplanet), so no extra hardware is needed in your home — the battery just needs stable wifi, typically 2.4 GHz. NM1 bids the capacity into Energinet’s FCR-D auctions, and activations are short — seconds to minutes — and designed to affect neither your comfort nor your equipment. Control by electricity price, so the battery also charges in the cheap hours, is something we are working on — it is coming soon.

The income is shared between you and NM1, and payouts are made quarterly as an ordinary bank transfer from NM1 — behind the scenes, we are settled via eSett, the joint Nordic settlement of the balancing markets. NM1 has been live since June 2025. You sign up via the get started page, and you can see how the earnings are calculated on the earnings page.

Checklist before you buy

1. Clarify the purpose. Should the battery primarily lift self-consumption of solar power, or should it also work for the grid? That affects the choice of size and inverter.
2. Check inverter compatibility. If the battery is to deliver ancillary services, the inverter must support remote control. See which batteries and inverters we can connect before you sign.
3. Read the warranty. Look at what usage pattern the warranty requires and how much residual capacity is guaranteed.
4. Be conservative in your maths. Use cautious assumptions and do not base the purchase on a single year of high market prices.
5. Check your wifi. The battery needs a stable connection, typically 2.4 GHz, to be controlled.
6. Choose open control. A battery that can join a virtual power plant has more income legs than one locked to a single function.

A home battery is a big decision, but the maths improve considerably once all three income legs are counted. Start by seeing what your battery could earn on the earnings page — and read why the grid pays for fast flexibility in our article on ancillary services.