Solar energy collection and storage - Solar Energy Sciences and Engineering Applications - page 119

Solar energy collection and storage

Brian Norton
Dublin Energy Laboratory, Dublin Institute of Technology, Dublin, Ireland

4.1 SOLAR THERMAL ENERGY COLLECTORS

4.1.1 Overview
Different types of solar thermal collectors provide energy in the form of heated

•

water for direct use (Rabl, 1985)

• aqueous solutions, usually of glycols for freeze damage prevention (Norton and

Edmonds, 1991; Norton et al., 1992), for hot water production

• air (Norton, 1992), usually for space heating

• specialized heat transfer fluid, mainly in solar thermal power generation (Duffie

and Beckman, 1991)

• steam, also in solar thermal power generation systems (Kalogirou, 2003)

• inherent energy storage as in integral passive solar water heaters (Bainbridge, 1981;

Smyth et al., 2006) and solar ponds (Leblanc et al., 2011)

• fluid with electricity production from a photovoltaic module (Norton et al., 2011)

employed as the absorber

• refrigement or volatile fluid (Shreyer, 1981; Ong and Haider-E-Alathi, 2003)

• material undergoing solid to liquid phase change (Sion et al., 1979; Rabin et al.,

1995).

The two principal solar thermal collector designs employed for space heating and
hot water supply are the flat-plate solar collector and the vacuum tube solar collector
the latter may be employed with line-axis concentrators . Flat-plate solar collectors
have now been overtaken in total global numbers by the increasingly popular vacuum
tube solar collector. The latter has a higher efficiency at higher temperatures and has
become relatively inexpensive due to high production volumes of the all-glass type,
particularly in China (Weiss and Mauthner, 2010). Integral collector-storage systems
range from small-scale domestic water heaters to very large scale solar ponds. The for-
mer were the first mass-produced solar water heaters (Butti and Perlin, 1980) whereas
the latter are site-specific designed civil engineering projects (Leblanc et al., 2011).
Though most systems produce heated fluids for domestic, industrial (Kulkarni et al.,
2008) or power generation applications, more esoteric users of solar heat include ster-
ilization of medical equipment (Bansal et al., 1988) to the passive protection of grape
vines from frost damage (Smyth and Skates, 2009).