Just borrowed this from the library and thought I would have a grumble before I took it back.
It is basically a description of how to build a wooden box.
Tells you to put either a conventional steel radiator in the box, or make up a grid of copper pipes.
Then tells you if you want to mount it on the roof you should drill through the tiles and screw some angle iron on, or if the tiles are brittle then replace them with 'some other roofing material that you can drill through'. No advice on the alternative roofing material.
No advice on how to achieve this safely on the roof of a two storey house with a box full of steel radiator under one arm. [Certainly no inclusion of the cost of scaffolding in the overall pricing]
The pricing was very dubious as well - claimed to get your money back in about 5 years but didn't seem to account for the cost of the second (preheat) cylinder you would need to install and all the plumbing involved.
On the subject of the preheat cylinder - the design shows the solar panel heating what looks like a conventional hot water cylinder which then feeds water from the top into the bottom of the existing cylinder where the cold feed normally goes.
Now as far as I can see this means you only start to get the benefit from the solar heating when you use a tank full of hot water which has been heated by other means. If you want to run on solar hot water only in the summer you have a major problem - assuming your main hot water tank is full of cold water you start to draw off cold water and hot water from the preheat cylinder enters the main cylinder from the bottom where it starts to rise by convection and mix with the cold water.
Looks to me as though you would have to run off a lot of water before you got warm water out of the taps, let alone hot.
Why not just buy a single cylinder with two heat exchangers? As you are buying a second cylinder anyway this could replace the original hot water cylinder and benefit directly from any solar heating.
Gaaaahhhhh!
Told you not to get me started!!!!
Author is Paul Trimby Published by the Centre for Alternative Technology. Courtesy of Blue Peter.