Evacuated solar tube panel

[Jane Maries]

I would like to purchase one of the 20-tube solar panels
How do I know this will be compatible with my existing water tank which is already heated by a gas boiler and an optional immersion heater - or do I need separate tank?

Do the panels come with all the bits to install or do I buy these separately?

Is it really £395?

Look forward to hearing from you - many thanks

Jane Maries

[NickW]

Jane

I purchased a panel from Navitron last year at the price you quote. Due to other circumstances I did not install until March. I assume you are planning a DIY installation - if so you will need a certain level of plumbing and electrical wiring experience.

For the particular system I installed - which was superimposed onto an existing system with a boiler I installed another hot water cylinder in the loft that collected the solar heat. This then feed the existing cylinder heated by the boiler. The saving is in the fact that water feed from the solar tank does not need as much energy to bring it to temperature.

The materials I needed for this system were

A panel
A solar Controller  I paid £500 for the panel and controller from Ivan

A horizontal 125 litre hot water cylinder £135 (from Plumb City)

I used a cradle from an old bath to stand the cylinder on - otherwise this would have cost £35

I used a 2nd hand pump - cost £10

20 metres of 15mm copper - £20

6 metres 22mm copper pipe £15

Extra Insulation for tank £10

Pipe insulation £10

Miscellaneous brass fittings - pump fittings, gate valves, drain cocks, check valves £20

Miscellaneous copper solder fittings - couples, reducers, tees, elbows £20

Builders Steel band to fix panel to roof (band fed under tiles and connected to rafters £5

Miscellaneous electrical materials - cable, junction box, fuse box  £10

Other bits and pieces £50

Total cost was £820. Installation was about 3 days. Based upon the efficency of the boiler, the price of gas and output of the panel the return is about £58 per year - so margins are pretty slim.

Regards

Nick

[tlc]

jane,

perhaps you could fit a panel to your existing system by connecting the panel to a retro-fit solar coil that replaces the optional immersion heater element. so long as this is fitted from the top of the cylinder it should be ok. navitron supply these, have a look on the site.

[Ivan]

The best option is a twin coil solar cylinder - but these are expensive (the most expensive component in the system now, following yet more copper price increases recently) - so both of the alternatives mentioned are commonly used. The 'preheat' system works ok for high water users, but it is not so good for low water users, as in some cases the water will be heated to 60C by the preheat tank, then by the time it comes out of the main tank, it has been hanging around long enough to cool back down, necessitating topping up with conventional fuels.

Some customers are not able to go to the expense or hassle of a cylinder change (one customer told me his cylinder was inaccessible behind his boiler, requiring the boiler to be removed before he could change his cylinder!). My view is that although the twin coil cylinder is the best option, it is always better to have a compronised system rather than none at all. And you can always spend some of the money saved on a few more tubes, thus regaining some of losses in efficiency.

Ivan