How to store solar energy in companies and organizations – Enhancing the use of self-generated energy with battery energy storage systems

This article is the third part of our series on the fundamentals of energy storage.

Solar energy production and peak electricity consumption don’t always align. By storing the solar energy your company produces, you can use it when it’s most needed. This reduces electricity purchases from the grid, evens out consumption, and lowers both electricity and transmission costs.

In this article, we’ll explain how battery energy storage systems (BESS) can support solar energy solutions for businesses and organizations, the benefits of storing solar energy, and what to consider when getting started.

How to store solar energy?

Storing solar energy works much like any other energy storage. Electricity generated by solar panels is captured in a battery energy storage system, managed by smart control software. From there, it can be used later, for instance, when your electricity demand exceeds the production from your solar panels.

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What are the benefits of storing solar energy?

Storing solar energy offers multiple advantages:

• Lower electricity bills. By storing the energy you produce for later use, you purchase less electricity from the grid. You can also optimize your consumption during cheaper hours and sell electricity back to the grid when prices are high.
• Increased energy self-sufficiency. A battery storage system enables you to utilize more of the green energy you generate on-site.
• Reduced transmission costs. As a business, you may pay demand charges as part of your electricity transmission fees. With a battery energy storage system, you can smooth out consumption spikes, reducing these costs.
• Backup power during outages. A properly sized battery storage system provides a reliable backup during power disruptions or price spikes, keeping your critical operations running.

Practical Example: Oulun Baari, a service station focusing on fast EV charging, acquired a Cactos battery storage system to maximize the use of its over 1,000 square meters of solar panels. Solar energy produced during peak hours is now stored and used throughout the day for EV fast charging. Additionally, the stored energy helps the station manage demand-based transmission fees.

Is it worth storing solar energy?

While battery technology has advanced and prices have dropped, relying solely on production and consumption optimization may not always make solar energy storage financially viable. The solution lies in participating in ancillary service markets.

With a battery storage system that can participate in ancillary service markets, your investment can remain profitable year-round. Solar energy production varies significantly with the seasons, so it’s worth storing not only self-generated energy but also electricity purchased from the grid at lower prices. 

This approach positions energy storage as a holistic part of your energy strategy rather than just a means to store solar energy.

Ancillary service markets help making solar energy storage profitable

Some battery energy storage systems, such as Cactos, enable participation in ancillary service markets, providing a steady revenue stream and making the solution cost-effective for various businesses and organizations.

In these markets, transmission system operators (TSOs) maintain grid stability by purchasing frequency regulation capacity. In Finland, Fingrid, the Finnish TSO, compensates battery systems for their readiness to charge or discharge based on grid frequency.

For individual companies, the ancillary service markets are traditionally out of reach. However, by joining a pool of users, such as those using Cactos battery systems, businesses can benefit from the revenues these markets offer.

For instance, Cactos customers have successfully offset their leasing costs through ancillary market revenues. During 2023 and 2024, these revenues have, on average, matched or exceeded the leasing fees. While monthly variations exist, this long-term profitability often means that the system pays for itself through these markets. On top of this, businesses benefit from local electricity optimization.

How to get started with solar energy storage?

Companies and organizations have diverse goals for solar energy production and storage.

Beyond cost savings, many aim to increase self-sufficiency and boost their share of renewable energy. Backup power capabilities may also be a priority.

Whether you’re just exploring solar energy or already have a rooftop full of panels, consulting with professionals is the best way to start.

Cactos specializes in battery energy storage solutions for businesses and organizations. Along with advanced hardware, we provide the intuitive Cactos Spine control software. This software automatically optimizes your storage system’s operations based on factors like consumption, production, and electricity price fluctuations—maximizing your benefits at all times.

Your battery storage system also participates in ancillary service markets as part of the Cactos pool. This creates a steady income stream and makes energy storage a sound investment. With our leasing model, you can enjoy the benefits of solar energy storage at a fixed monthly cost without a significant upfront investment.

Our experts are happy to help you assess energy storage opportunities at your site. Contact us to discuss your needs.

Learn more about Cactos' solutions here.