No one who has sat in the midday sun in July in Andalucía would doubt is power. There’s certainly no shortage of energy. All we have to do is harness it. With an average of over 300 days of sunshine a year in southern Spain perhaps it’s not surprising that domestic hot water from solar energy has been mandatory on new builds since Oct 2006.
Systems are straightforward to install, reliable, durable and readily available. The collectors will work during overcast days even when there is no direct sunlight but will work best when in direct sunlight. Heat from the sun is transferred to water contained within the collector and circulated to a special solar cylinder where it can be topped up to a useable temperature as and when required by a conventional boiler or immersion heater.
Collector performance will be optimum when facing due south un-shaded and inclined between 25-60 degrees but in practice any situation between southeast and south west will result in only a 10% fall off in efficiency and can be considered acceptable. Even east or west facing elevations will provide around 80% of optimum and should be considered since an oversized collector can be fitted.
Some evacuated tube collectors can also be rotated within their manifold by up to 30 degrees in order to compensate for an unfavourable position. Consideration should also be given to mounting the collectors vertically on a wall or at ground level or flat roofs on purpose build “A” frames available directly from most suppliers.
Resultant savings in C02 omissions will vary according to the fuel being displaced and the hot water demand. A typical flat plate solar collector will save around 1000kg of C02 when displacing electricity.
Author: John Wolfendale
Bio: John is a founder of Eco Vida and is passionate about bringing modern design and construction practices to Spain. He believes a home which is warm in winter and cool in summer is largely a matter of design and selective use of materials. He is British and a Chartered Surveyor with 18 years experience living and working in Spain.