As the world continues to transition towards a greener future, the push to decarbonize economies through electrification and clean energy is driving innovation in battery technologies. While renewable energy sources like solar power are a cleaner alternative to fossil fuels, their output can be inconsistent, making energy storage a crucial component in enabling a seamless transition. The intermittency of solar power, for instance, necessitates a solution to regulate its variability, ensuring a stable energy supply even when the sun is not shining.

One approach to address this challenge is to store excess energy generated during daylight hours, when solar power is abundant, and utilize it during periods of high demand or when sunlight is scarce. This strategy enables solar power plants to optimize their energy output, making them more efficient and reliable.

Moonwatt, a Netherlands-based clean tech startup, is developing a battery-based energy storage system specifically designed for solar power plants. Founded in September last year, the company has created a tailored solution that includes dedicated battery enclosure hardware, inverter power electronics, and software to integrate and manage the storage system. By co-locating their storage system with solar power plants, Moonwatt aims to help them manage the variability of solar energy, increasing their revenue and reducing costs.

The startup’s solution targets solar plants with a capacity of at least a few hundred kilowatts, excluding residential photovoltaics deployments. Moonwatt’s system is built around sodium-ion cells, which offer a cost-effective alternative to lithium-ion batteries. Although sodium-ion batteries have limitations in terms of size and weight, they are well-suited for stationary installations like solar power plants, where space is not a concern.

By leveraging sodium-ion technology, Moonwatt’s storage system can help solar power plants increase their capacity factor by up to 80% and potentially double their internal rate of return (IRR). This is achieved by allowing plants to sell more solar energy, including during periods of high demand, and reducing costs associated with electrical infrastructure.

Getting more juice out of PV

According to Moonwatt’s co-founder and chief commercial officer, Valentin Rota, the company’s energy storage system enables solar power plants to increase their revenue by selling more solar energy, including during periods when the price of energy is more attractive. This is achieved by storing excess energy generated during daylight hours and releasing it during periods of high demand.

Rota highlights that Moonwatt’s solution allows solar power plants to double their IRR, which typically ranges between 8% to 12% for an average photovoltaic asset. By increasing the asset’s return to around 20%, Moonwatt’s system provides a compelling value proposition for solar power plants looking to optimize their energy output and revenue.

The founding team, which includes CEO Zukui Hu and CTO Guillaume Mancini, has a background in battery technology, having worked together at Tesla and other companies. They recognized the potential for battery-based energy storage to revolutionize the solar industry and founded Moonwatt to develop a dedicated solution for solar power plants.

The team’s experience in battery technology and solar energy led them to develop a system that combines battery hardware, inverter power electronics, and software to integrate and manage the storage system. By designing a system specifically for solar power plants, Moonwatt aims to provide a tailored solution that addresses the unique challenges and opportunities of the solar industry.

Moonwatt’s approach is centered around the use of sodium-ion battery technology, which offers several advantages, including better scalability, cost reduction, and a lower carbon footprint compared to lithium-ion batteries. The company’s distributed architecture and design allow for greater efficiency and a reduction in the cost of dispatchable electricity.

The overarching goal of Moonwatt’s system is to reduce the cost of electricity for dispatchable solar plants, making solar energy more competitive and attractive to investors and consumers. By optimizing energy storage for solar power plants, Moonwatt aims to play a key role in enabling the widespread adoption of renewable energy and reducing our reliance on fossil fuels.

Seed funding to step on the gas

Moonwatt has secured €8 million in seed funding to accelerate the development and commercialization of its energy storage system. The funding round was co-led by Daphni and LEA Partners, with participation from Founders Future, AFI Ventures, and Kima Ventures, as well as strategic business angels and customers.

The investment will enable Moonwatt to move forward with its pilot installation in Europe and prepare for commercial deployments in 2027. With the support of its investors, Moonwatt is well-positioned to capitalize on the growing demand for energy storage solutions in the solar industry.

According to Paul Bazin, Partner at Daphni, Moonwatt’s approach is “the breakthrough the industry has been missing.” He highlights that renewable power growth has exceeded expectations, but the lack of better energy storage solutions has limited its scalability. Moonwatt’s dedicated storage product for solar power plants addresses this challenge, providing a tailored solution that can help unlock the full potential of solar energy.

Rota emphasizes that Moonwatt’s ambition is to become a large-scale player in the energy storage market, with a focus on cost competitiveness and scalability. By optimizing energy storage for solar power plants, the company aims to make a significant impact on the transition to a greener future.

The decision to focus on solar energy was driven by its attractive economics and broad uptake, with solar power being deployed in over 120 countries. By concentrating on solar, Moonwatt can fully focus on making design choices that help plants get the most out of their asset, including reducing the costs of connecting their energy to the grid.

Looking ahead, Moonwatt’s solution has the potential to reduce the overall balance of plant costs by optimizing the use of grid capacity. By coupling solar and storage at a low voltage level, plants can share the same electrical infrastructure, reducing the number of transformers and cables required.

As the energy landscape continues to evolve, Moonwatt’s innovative approach to energy storage is poised to play a key role in enabling the widespread adoption of solar energy and reducing our reliance on fossil fuels. With its tailored solution for solar power plants, Moonwatt is helping to unlock the full potential of renewable energy and pave the way for a more sustainable future.