The choice is between flat-plate panels and evacuated tubes. Here’s what they look like.

Do you prefer the look of one over the other?

Do you want high quality (quality and price are related)? If the quality / performance is equal, then evacuated tubes will be more expensive. If you ignore quality and focus on price, you can buy an evacuated tube system cheaper than flat-plate. It may be false economy, however – the important thing is the amount of hot water the system can deliver over its lifetime. That will be more important than relatively small savings on the purchase of the system.

Evacuated tubes tend to be higher-performance – so you’ll need a smaller area for the same energy output. This may be important if you don’t have much roof space. Flat-plate systems historically have been more reliable over longer periods of time – there’s less to go wrong, and they tend to operate at lower temperatures. Flat plates typically reach a maximum temperature of 200°C, evactuated tubes 300°C. Higher temperatures can damage the heat transfer liquid more quickly, which can produce solids within the liquid that will start to clog up the system. It’s more difficult to evaluate the long-term reliability of evacuated tubes because, although they’ve been around since the 80s, the technology is different now, so we’re not comparing like with like.

Europe-wide, there are many more flat-plate systems installed than evacuated tubes, and there are various reasons for that, including price, aesthetics and perceptions of reliability. The experience of installers in our network suggests that fewer problems occur in flat-plate systems. If you want more information on the different types of panel, you need to do a bit more work. Again, we suggest you read our book – it contains a lot more information than we can squeeze into this guide.