Do photovoltaic panels work without sunlight? With thermal battery storage, yes.

Solar energy represents one of the most promising and sustainable energy sources of our time. However, its effectiveness is often questioned due to the intermittency of solar radiation. Photovoltaic panels, in fact, produce electricity only during daylight hours, creating a significant challenge for energy supply continuity.
An innovative solution to this problem is the use of thermal batteries, which allow thermal energy to be stored for later use. In this article, we will examine how thermal batteries can improve the efficiency and performance of a home’s photovoltaic system, making it possible to use photovoltaic panels even without sunlight.

How does a home system with photovoltaic panels work?

Photovoltaics are an increasingly common solution on residential rooftops. A system under 3kW guarantees, at a minimum, coverage of the energy needs for electrical devices. A system of 4 to 6 kW, on the other hand, can also cover the energy requirements for heating and hot water production.

Typically, the energy produced by photovoltaic panels that is not immediately consumed is stored in an electric battery, allowing it to be used during times of the day when there is no more sunlight.

To meet the energy needs of electrical devices, no conversions are necessary. However, to meet the demand for heating and hot water, electrical energy must be used indirectly. For this reason, heat pumps are used: the electricity produced by photovoltaics is used by the heat pump to produce hot water. This process occurs with a specific performance index called COP (Coefficient of Performance).

Factors That Influence the COP

The COP can vary based on:

• External temperatures
• The water supply temperature

If a home has radiant floor heating, only 35°C water temperature is needed to heat the space. Higher temperatures are required, however, for wall radiators.
During the colder hours of the day, the COP becomes lower, making the conversion from electricity to heat less efficient. This leads to a considerable energy demand from the grid.

Advantages of Thermal Batteries

To avoid this issue, thermal batteries, as an alternative to common electric batteries, are an ideal solution: rather than storing energy in electrical form, they allow heat to be stored, enabling the heat pump to operate during times of day when it can function optimally.

Thermal batteries can store large amounts of thermal energy, which can be released immediately when needed, ensuring a constant energy supply. Here is a summary of the main advantages:

1. Increased photovoltaic system performance: thermal batteries allow for optimal use of the energy collected by the panels, reducing losses and improving the overall efficiency of the system.
2. Improved overall efficiency of the photovoltaic system: the thermal storage capacity enables stable and predictable energy production, enhancing system efficiency.
3. Reduced dependency on weather conditions: With thermal batteries, energy collected during daylight hours can also be used at night or on cloudy days, ensuring a continuous energy supply.
4. Flexibility and scalability: thermal batteries can be integrated into systems of various sizes.

Thermal batteries provide an effective solution to overcome the limitations of photovoltaic panels related to the intermittency of solar radiation. With their ability to store thermal energy, these batteries allow for continuous and reliable use of solar energy, even during dark hours or cloudy days. This not only enhances the overall efficiency of photovoltaic systems but also reduces dependency on weather conditions and the power grid. Investing in thermal batteries is a step forward towards a more sustainable and resilient energy future, ensuring a constant and optimal energy supply for our homes.