EcoSolar Energy Conscious Design Limited
4
Figure 3. EcoSolar 12Volt UVR61 controller
Basics of system sizing
As a rule of thumb solar hot water systems are often sized on the basis of 1m2 of collector area per
50 to 75 litres of water storage or per person. For instance, based upon 75litres of water storage per
person a two person house hold should be able to comfortably utilise an existing 135 or 180 litre
cylinder. In many cases solar collectors are able to be retrofitted on to an existing cylinder and
providing the issues associated with frost protection, backup heating, excessive temperatures and
volume of water storage are effectively managed, can provide the most cost effective solution with
very favourable returns for the consumer. Such retrofitted systems should be installed such that they
can be extended and the cylinder replaced with a larger one once hot water usage increases i.e. the
couple start a family. A four person household would require a larger system with a 300 litre hot
water cylinder and multiple collectors.
The sizing of solar water heating systems for conventional housing is fairly well known
however, sizing of commercial or larger scale multiple residential sites requires extensive engineering.
The engineering of such systems would require computer simulation of hot water loads and solar
gain to refine the system design. Energy Conscious Design have completed many engineering,
feasibility reports and system designs for high rise multi tenancy dwellings, hotels, retirement villages,
offices, schools, as well as other commercial applications and swimming pools. This engineering
utilises computer software, this together with our historical experience are able to determine if solar is
suitable and deliver well engineered designs for each application.
System operation and control
System operation and control was discussed in previous articles last year. The solar water heating
system will operate automatically by recovering heat from the solar collector to the hot water
cylinder. However, all solar water heating systems need a backup heating system, this needs to be