Solar evacuated tubes have gained greater market share of the solar hot water market since the turn of this century, although are more expensive to manufacture than flat panel thermal collectors.
- Greater absorbance of radiant heat during the early and latter periods of the day
- Greater heat absorbance during overcast conditions
- Reduced heat loss via conduction and convection
- Spacing between each evacuated tube and curved nature reduce hail impact forces
- Reduced snow build up issues with evacuated tubes due to spacing
- Greater longevity of evacuated tubes over flat panel, in excess of 25 years.
- In case of breakage, individual tubes are more cost effective to replace than an entire flat panel system
Flat plate collectors however, have approximately 70% greater absorbance area per installed square meter and therefore absorb more radiant heat during the middle period of the day. This can be a disadvantage in Summer when excessive heat during can create high pressure which require venting and water loss, and increase stress on the hot water system.