better generation

Imagine you painted a radiator black, connected it up, and stuck it on your roof on a sunny day. This is the basic idea behind solar hot water, and even in cloudy UK conditions a nicely set up system can give you loads of free hot water. Because the technology is relatively simple and fairly cheap, solar hot water systems are usually considered to be the most economic type of micro generation system to fit to your home.

Installation case study

Our friend John is a micro generation enthusiast who has just finished having a solar hot water (solar thermal) system installed on his central London house. The installation, though ultimately successful was not all plain sailing so we asked him for a run down of his experiences. We should be clear, this isn't one of our 'projects' - its a write up of another company's work!

If you'd like to tell us about how your recent installation went, positive or negative, drop us a line and we'll publish it for all to see! 

The equipment used:

• 2 x CU210 Sammler flat thermal panels 
• an 'A frame' for flat roof mounting
• Resol controller including temperature sensors etc
• Pumping station with mains powered pump, including valves, pressure gauges, pressure vessel etc. (Cost: £1797.50 inc VAT)
• 220 litre horizontal hot water tank (and 2nd heat exchanger for heating - unused) with electrical immersion back up. (Cost: £528.75 inc VAT)
• Stainless steel ready insulated flexi pipe (optional) (Cost: £164.50 in VAT)

Above equipment supplied by Bright Light Solar of Machynlleth, Wales.

In action

Once installed, the system has performed flawlessly. Even on days with brief sunny spells, the panels heat up very quickly and transfer the energy to the hot water tank within a few minutes. September 2006 was warm but not spectacularly sunny and the system still managed to supply 100% of our hot water needs. In early October, around 2-3 hours of morning sun has translated into a 20⁰C uplift in our hot water temperature.

...But it was tricky getting there

If there was one major weakness in the whole process, it was the way the package we bought was put together. Although the supplier, Bright Light Solar were extremely helpful throughout, there were some glaring omissions in the components they originally delivered, which delayed the installation process and caused our plumber anguish. Here are some things to look out for when doing your installation to save on solar induced headaches.

• Make sure the pipe connectors for the flow & return pipes to the panels are the right size (ours weren't)

• Check the instructions on connecting up the panels are correct (ours weren't)

• and check there is enough antifreeze fluid to fill the system (guess what....)

You may well get a second hot water tank heat exchanger (designed for heating systems) that you don't seem to need. But with ours It turned out you actually need to fill it to improve the heat flow between the panels and water supply. 

Installation (aka comedy of errors)

Bright Light's faulty instructions only came to light when the plumber eagerly connected the whole system precisely as instructed, but equally precisely the wrong way round, with cold water entering the panels at top left and leaving at bottom right and not able to flush out air bubbles.  After much head scratching and advice from Bright Light the system was emptied and the pipework reversed, then refilled and re-pressurised. Even then, the hot water was only tepid, or there simply wasn't much of it, which seemed very odd on hot August days, at which point I noticed that the hot water outlet was sprouting out of the side of the tank, not the top...

A somewhat embarrassed plumber then drained the whole system (again) rotated the tank 90 degrees, refilled and pressurised it; and finally, voila! - it all works.

I've ended up inventing a Mickey-mouse expansion tube for the top of the tank to allow the water level to go up and down as the tank heats and cools.

To be fair, Bright Light willingly corrected the errors and gave advice as the installation process proceeded but it was still much harder than it needed to be.

Beware the controller

In true Germanic fashion, the controller has every conceivable setting and information read out, including the ability to control a back up boiler, measure the Kwh of heat delivered, adjust for the heat absorbing characteristics of the fluid in the system (and probably tell you what colour pants to wear on any given day). However, in a stunning omission that must be the equivalent of forgetting to put a reverse gear in a Mercedes Benz, there is no timer clock (that I can find). So although the controller senses from the water temperature when to boost up the temperature with the backup electric immersion heater, it doesn't know what time of day, or day of the week it is, which of course is a waste of energy as you might well not be there to use it. So the next step will be to get an electrician to install a separate timer and relay switch to wrestle this part back under control.

Conclusions?

The quality of the kit is excellent and I fully expect it quietly to do its stuff for the next 20 years, unattended. It's been let down by it not quite fitting together as a system and a lack of thought into many of the details, such as insulation around the tank fittings to reduce heat loss, mis-labelled tank fittings and somewhat redundant heat gauges on the flow and return pipes. However, my overall score is 6.5 out of 10.