As the world pushes toward cleaner energy, the combination of heat pumps (HPs), photovoltaic (PV) systems, and thermal energy storage is becoming increasingly vital in the residential building sector. New research from RWTH Aachen University [50.8°N, 6°E] has uncovered critical insights into how optimising these systems can help meet energy demands more sustainably and cost-effectively.
The Role of Heat Pumps in Sustainable Homes
Heat pumps are highly efficient devices that use electricity to provide both heating and domestic hot water for homes. They can drastically reduce a household’s carbon footprint by replacing traditional fossil-fuel-based heating systems. Combined with PV systems, which generate renewable electricity, heat pumps offer a way to power heating systems with clean energy. However, a key challenge is the mismatch between the supply of solar energy and the demand for heating—during the day, PV generates the most electricity, while heat demand is often higher at night or in the winter months.
The Power of Storage
Thermal energy storage, such as water-based systems, helps to bridge this gap by storing excess solar power generated during the day and using it later when heating demand increases. The research shows that optimising the size and control of both the heat pump and the storage system is crucial to maximising efficiency.
The study explores various design and control strategies to find the most cost-effective and energy-efficient solutions. It highlights that using PV alone, without an optimised storage solution, often leads to less-than-ideal outcomes. The research demonstrates that the rule-based controls commonly used in practice can still yield highly effective results, even if they are simpler than more advanced predictive controls.
Price Assumptions: A Key Factor in Design
One of the most exciting findings of the study is that electricity price assumptions have a major impact on the optimal system design. When electricity prices are high, larger heat pumps become more economically attractive because they reduce reliance on the grid by using more solar-generated electricity. The research shows that adjusting for higher operational costs leads to larger HP sizes and greater savings in the long run.
Moreover, the research investigates how the feed-in tariffs—the price paid for excess electricity sent back to the grid—affect the decision to store or sell excess PV power. The findings indicate that higher self-sufficiency can be achieved when there is greater financial incentive to use stored power for heating rather than feeding it back into the grid at lower rates.
Practical Implications for Sustainable Energy
For anyone involved in sustainable building design or retrofitting, these findings provide a clear takeaway: optimising the design of heat pumps and storage systems, especially in combination with PV, is critical for reducing energy costs and emissions. The study underscores that while PV has a smaller impact on the overall design, price assumptions and control strategies are key drivers of optimal system performance.
This research offers practical insights into how we can better design energy systems to support the transition to a more sustainable, low-carbon future. By making the right choices in heat pump sizing, storage capacity, and control methods, we can ensure that homes are not only energy-efficient but also equipped to handle fluctuating energy demands with renewable power.
Looking Ahead
The findings pave the way for further research into dynamic energy pricing and advanced control strategies, which could lead to even greater savings and more efficient systems in the future. With renewable energy becoming an essential part of our daily lives, innovations like these are critical for ensuring that we can meet our energy needs sustainably and cost-effectively.
Source
Heat pump and thermal energy storage: Influences of photovoltaic, the control strategy, and price assumptions on the optimal design, Renewable Energy, 2024-12
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