Storing solar energy increasingly pays off

Does your business have rooftop solar panels, or are you thinking about purchasing them? One of the questions you need to consider is what to do with your excess solar energy. Will you feed it back to your energy provider, or will you store it for later use? Improved batteries and government policy are making storage a more appealing option. Discover the benefits of home solar storage.

The Netherlands must be energy-neutral by 2050, and one of the missing pieces of the puzzle in this energy transition is the storage of renewable energy. Now that a growing number of individuals and businesses are generating energy using their own solar panels, the market for local storage is changing as well.

Net metering is being discontinued

While you can currently still benefit from net metering (where you can feed self-generated energy back to the energy grid), this is set to be discontinued. You should therefore consider the following issues:

• After 2025, there will no longer be a financial incentive for the net metering system. Net metering currently makes it financially rewarding to feed back energy and offset this against the energy consumed.
• In some areas in the Netherlands, the option of feeding electricity back to the grid is no longer available, as the grid would become overwhelmed. You can preserve your energy by storing it yourself.
• The batteries for local storage are improving all the time.

Self-sufficiency through solar energy storage

Klimpark21, an outdoor park located in the town of Nieuw-Vennep, reveals how you can store solar energy and use it to build a sustainable, self-sufficient future. The outdoor park has been 100% self-sufficient (off-grid) since 2017. All the energy is supplied by 12 solar panels, which are connected to 8 batteries. “The solar energy supplies the cash register, the Wi-Fi, the refrigeration system, and the rainwater pump, as well as our electric skateboards, which children use to play in the park,” owner Michael Sevenhuijsen explains.

Storing more than half in battery

Installing a power connection in the outdoor park was too expensive. While solar energy is free, the required equipment obviously is not. “The batteries cost €285 each. It cost around €8,000 altogether. This price includes 12 solar panels, 8 batteries, an inverter, a control box, and cables. The subsidy for solar PV panels has been deducted from this amount.”

Open to the public from April to November, the park gets plenty of sunny days. “Since we are open only during the summer months, we can run on solar energy virtually every day. On an average day, I use 40% of the solar energy directly, while 60% is directed to our battery system. On a sunny day, it takes just one day to charge up to 80%.” A control box regulates this process, and Sevenhuijsen can check his smartphone to see the level of solar energy stored. “On sunny days, It will store 1.2 kWh of solar energy, and half this amount on cloudy days. The park requires a maximum continuous power of 120 W.”

Solar energy storage with a battery system

Experts believe that if you are looking to store solar energy yourself, a battery system is currently the best option.

Benefits of batteries

“A battery system becomes more appealing if you use it for multiple purposes,” says Jeroen Panis, an expert in electric energy storage (EES) at Indutecc. This company supplies products such as a sustainable battery manufactured in Sweden. In addition to solar storage, he says:

• Proactively managing overall demand to eliminate short-term demand spikes (a process known as ‘peak shaving’). Sometimes you might use more energy at specific times, for example because a machine only runs several times a day.
• Supplying large quantities of energy at once, for example to quickly charge an electric vehicle.
• As a safety net in the event of a power outage. Keep in mind that the inverter for your power system must be suited to this purpose, which is not always the case.
• Topping up your power supply on cloudy days or in the dark.

“An additional advantage is that it potentially eases the burden on your electricity connection, which saves you money. But you will still need a grid connection, particularly during the winter months. Battery systems have a limited capacity and supply power for a relatively short period of time.”

Quantities and payback period

“The purpose for which you want to use your battery determines how much you need in kWh,” says Rob den Exter. He is an energy storage expert at StoredEnergy, a consulting firm and property development company specialising in energy storage. “For SMEs, this varies from 10 kWh to 500 kWh. There is no need for maintenance, and manufacturers cite lifecycles of between 8 and 15 years. Payback periods still tend to be long – usually a lot longer than for the solar panels themselves.”

Sustainability and safety

There are different types of batteries available, and which type you choose affects your system’s safety and sustainability. “Lithium batteries are relatively expensive, hard to recycle, produced from scarce natural resources, and flammable.” For safety purposes, local authorities may require that you install your battery inside a container outside your building,” Panis warns. “These days, there are also sustainable nickel-metal hydride (NiHM) batteries available. They are not flammable, made from materials that are easily available, and easy to recycle.” “Efforts are also underway to develop more environmentally friendly batteries, including saltwater and flow batteries,” Den Exter adds.

No interim maintenance

Klimpark21 made a point of choosing lead-acid batteries instead of lithium ones. Sevenhuijsen: “These batteries will last you around 7 years, after which they are replaced and recycled. “They do have a longer lifespan. Lead-acid batteries are easy to recycle, as well as being cheaper. There is no need for interim maintenance.”

Smarter and more sustainable solution

Battery system technology is rapidly evolving, and Panis believes smart local power grids (microgrids) have the future. “You will find microgrids in residential neighbourhoods or business parks, where all solar panels are linked to a central neighbourhood battery. You eliminate individual batteries, which is more efficient and more economical.”

Ask an expert

Panis concludes by sharing a tip for anyone interested in storing their own solar energy: “It is always based on customised solutions, and is about the overall package, not just about the batteries or solar panels. For example, the required inverter must be compatible with both the batteries and the solar panels. You should therefore hire the services of an expert, who can crunch the numbers for your scenarios and provide the solar panel package.”

Sevenhuijsen of Klimpark21 agrees: “Our supplier delivered a ready-to-use solar energy kit, including everything from solar panels to a battery system.”