As providers of both flat panel and evacuated tube collectors we will discuss flat panel systems vs evacuated tube systems in this section.
A flat panel system is not a frost resistant system, and therefore should be used as an indirect system with glycol in any area where temperatures drop below +4°C to protect the flat panel collector from damage in case of frost. The glycol (anti-freeze liquid) inside the flat panel should be replaced every 2 years in order to retain its effectivity. This means that these systems are maintenance systems. These systems are also dependant on direct heat from the sun, meaning that it is not as effective during cold periods and totally ineffective on cloudy days. These systems should face directly North.
An evacuated tube system is a frost resistant system and can be used as a direct system in any area with any temperatures. The evacuated tube systems are totally maintenance free, and expected lifespan is 20 years+ before maintenance should become necessary. The evacuated tube systems work on radiation, and is not in any way dependant on direct heat. This means higher effectivity, even on cold or cloudy days.
The main benefits of evacuated tube systems vs flat panel systems are:
· Frost resistant
· Possible to convert any existing electrical geyser
· Highly effective even on cloudy or cold days
· Tubes have been SABS tested for 37mm hail resistance
· Maintenance free systems
· Expected lifespan 20 years +
· Effectivity can be adjusted
· Collector can be repaired, and does not need to be replaced in the event of physical damage
· Direct heating system