This paper looks at the barriers and opportunities for the mass deployment of solar-thermal technologies and offers a vision for the future of solar-thermal systems.

HEADLINES: -Heat constitutes about half of total global energy demand. Solar heat offers key advantages over other renewable sources for meeting this demand through distributed, integrated systems. -Solar heat is a mature sustainable energy technology capable of mass deployment. There is significant scope for increasing the installed solar heat capacity in Europe. -Only a few European countries are close to reaching the EU target of 1 m2 of solar-thermal installations per person. -One key challenge for the further development of the solar-thermal market arises from issues related to the intermittency of the solar resource, and the requirement for storage and/or backup systems. The former increases investment costs and limits adaptability. -An analysis of EU countries with good market development, suggests that obligation schemes are the best policy option for maximising installations. These do not present a direct cost to the public budget, and determine the growth of the local industry in the long term. -Solar-thermal collectors can be combined with photovoltaic (PV) modules to produce hybrid PV-thermal (PV-T) collectors. These can deliver both heat and electricity simultaneously from the same installed area and at a higher overall efficiency compared to individual solar-thermal and PV panels installed separately. --Hybrid PV-T technology provides a particularly promising solution when roof space is limited or when heat and electricity are required at the same time.