Solar Energy Perspectives - IEA

Solar Energy Perspectives: Buildings
converts the DC from the modules into AC that can be exchanged with the grid. However,
a number of appliances in buildings use DC. The wide variety of voltages makes a distinct
DC circuit in houses impractical. If batteries from electric vehicles become an important
customer/reservoir for PV modules, it might be worth having some direct current link
between the modules and the batteries, instead of undergoing a double DC-AC-DC
conversion, with its inevitable losses.
Another area of investigation could be optimal population/housing density. Greater
population density reduces heating losses and transport needs, but also reduces the
surface area available for collecting solar energy. Small detached dwellings offer larger
surface areas for a given overall volume than bigger buildings, but require much more
transport. If walls and windows are inefficient, densely packed urbanism can reduce the
losses. With highly efficient envelopes that produce more energy than they allow to
escape, smaller buildings could be preferred. Ultimately, the optimal choice – only from
an energy point of view – could depend on the energy consumption in transport, and its
origins.
Policies
Policies for deploying solar energy solutions in buildings are quite diverse. There may well
be a need for broad policies to support solar electricity, and others to support direct solar
heat in various forms. The latter policies will be further developed in the forthcoming IEA
Technology Roadmap for Solar Heating and Cooling, to be published in 2012.
• An integrated approach to the deployment of solar energy should aim to foster the
deployment of the whole set of technologies that would facilitate the use of solar
energy in buildings, and the use of buildings as decentralised generators of solar
electricity. This may include: new energy standards for new buildings; the promotion
of heat pumps, passive solar designs and solar water heating; and speeding the
refurbishment of existing buildings (Figure 4.11).
• It should also include measures to encourage and facilitate the development of relevant
skills for project developers, architects, thermal engineers, and other building professionals.
• Product certification and guarantees of results, developed in cooperation with the
industry, are essential to gain consumer confidence in new products. Streamlining and
harmonising certification procedures, if possible at an international level, is key to
creating global, efficient product markets. Various policy aspects have been addressed in
the IEA Technology Roadmap: Energy-Efficient Buildings (IEA, 2011d ).
• Environmental non-governmental organisations have suggested tying the authorisation to
benefit from building-integrated or building-adapted PV feed-in tariffs to the refurbishment
of existing buildings to reduce heating loads (see, e.g. France Nature Environnement,
2011). This may prove counter-productive, as the dynamics and participants in both
developments are significantly different. Artificially combining them may impede both,
instead of making one support the other. However, emerging market products that could
play both roles, from PV thermal hybrid collectors to roof elements that bear PV collectors
while ensuring good thermal insulation, could and perhaps should receive specific
incentives.
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© OECD/IEA, 2011