Is it advantageous to wait to buy a battery for solar panels?

Many who invest in solar panels consider whether they should also purchase a battery at the same time – or wait. Here we review when it might be advantageous to postpone the battery purchase, and when it might pay to invest in it immediately.

Advantages of waiting to buy a battery

  1. Falling prices and technological development Battery prices have historically been falling, and batteries are becoming both better and cheaper. If you wait 1–3 years, you can often get more capacity for less money.
  2. You gain insight into your consumption pattern By first installing solar panels and waiting with the battery, you can collect data on your own electricity production and your actual consumption – so you can later size the battery optimally.
  3. Lower start-up costs If finances are a factor, you can choose to start with a cheaper system and postpone the investment in a battery until later – where it can possibly be financed separately.

Disadvantages of waiting

  1. You miss out on greater savings and flexibility Without a battery, you typically only use 30–40% of your own electricity directly. The rest is sent out to the grid and sold cheaply (approx. 60–80 øre/kWh). With a battery, you can store the electricity and use it later – or sell it intelligently when the electricity price is high.
  2. Expensive or technically difficult retrofitting Retrofitting often requires replacement or addition of a hybrid inverter. This makes the project more expensive and complex if you do not prepare for it from the start.
  3. No access to the grid balancing market Grid balancing is an opportunity to earn DKK 3,000–5,000 annually by helping to balance the electricity grid. This requires a battery – without a battery, you miss out on this extra source of income.

Economic example – with and without a battery

Without battery Price: DKK 70,000 (solar panel system without battery) Annual savings: approx. DKK 13,000 Payback period: approx. 5.4 years With battery (10 kWh) Price: DKK 110,000 (solar panels + battery) Annual savings incl. grid balancing: approx. DKK 20,000 Payback period: approx. 5.5 years But: higher self-consumption, lower electricity bill, and access to grid balancing These calculations are based on an annual electricity consumption of 8,000 kWh and an electricity price of DKK 2.5/kWh. Actual results depend on your consumption, roof conditions, and market development.

What does EcoRay recommend?

If finances allow, it is typically most advantageous to buy a battery together with solar panels. You get a more efficient solution from day one, increase your energy independence, and can gain access to balancing income. But if you want to wait, it is important to prepare the system correctly – e.g., by choosing a hybrid inverter. Then you are ready to add the battery when the time is right for you.

At EcoRay, we base our recommendations on your specific situation and show you calculations both with and without a battery – so you can make an informed and profitable choice.