Hot water demand is continuously growing globally, and many IEA SHC member countries have 2030 commitments/targets to achieve a higher solar fraction of their economies. At present, ~16% of residential energy consumption in IEA countries goes to water heating (according to 2018 IEA data). However, the ‘solar share’ of low-temperature heating is still relatively low —only 2.1% of space and water heat demand was being met by solar thermal in 2018, and this mainly comes from evacuated tube systems installed in China. This same report states, “to be in line with the Sustainable Development Scenario (SDS), the share of clean energy technologies needs to exceed 50% of new heating equipment sales by 2030.” To investigate the best way to fill this gap for solar hot water, SHC Task 69 focuses on two technologies that are expected to play the biggest role in the solar hot water market in 2030: solar thermal thermosyphon and solar photovoltaic (PV) derived hot water heating systems.