Policy Initiatives for Solar Photovoltaic Hot Water
April 2026 - PDF 0.47MB
Editor: Luis Christian Navntoft, Tony Day, Baran Yildiz, Robert A. Taylor

Space and water heating consumes almost half of global energy use in buildings. Keeping homes warm in winter and providing hot water for sanitary needs represent essential energy services. Worldwide, around 40% of households require space heating during part of the year, with heating being a major component of home energy expenditure, especially in colder climates where nearly two thirds of heating energy still rely on fossil fuels (IEA, 2026).

 

While energy efficiency for building space heating has been steadily improving over the last decades, the energy needs to produce domestic hot water (DHW) has remained consistent. Consequently, the share of the energy for DHW in the total energy balance of buildings has increased in recent years and this trend will likely continue with space heating reductions and deployment of high efficiency lighting and appliances. Building legislation on efficiency of indoor space conditioning has become stricter while the energy demand for DHW has been somewhat overlooked. In addition to the continuous improvement of the building's envelope, populations have changed their practices and requirements regarding DHW.

The Emergence of PV Hot Water Systems
A Technology Brief
April 2025 - PDF 1.35MB
Editor: Robert A Taylor, Tony Day

As photovoltaic (PV) system costs dramatically reduce, they are becoming economically viable as a technology to replace gas, grid electricity, and even solar thermal collectors as an energy source for low-temperature heating applications. The pairing of PV electricity with domestic water heating represents an under-explored—but rapidly emerging—opportunity for innovation, self-sufficiency, and sustainable modernization. In some regions, the household domestic hot water demand is over 50% of total household energy consumption. Thus, at the residential scale, the road to a low-carbon future must include sustainable solutions for domestic hot water.