SOLAR HOT WATER – DIY
CASE STUDY SHW02
WARWICK
INSTALLED:
September 2005
FUEL REPLACED
Gas
DESIGNED TO SERVE
2 adults
PROPORTION OF NEEDS MET
approximately half of [annual] hot water needs are met
PROJECT IDEA
What I did:
Construct passive solar hot water heating system to supply some of the domestic needs
Why I carried out the project:
1. With retirement pensions at risk of erosion compared to the rising costs of essentials this self-help activity is one of the few options available
2. General ambition to help with global need for frugal use of resources
What type of equipment was installed?
The installation is entirely home built but with all new materials.
• It comprises four one square metre panels using copper sheet coated with specialist paint and soldered to 15mm copper tubing to capture heat. The panels are covered in a plastic cellular pane to reduce wind effect loss.
• Transfer is entirely by thermosyphon onto a secondary coil in the recently replaced central heating hot water tank.
• A small header tank keeps the circulating liquid topped up. There is a little evaporation as it is an open system. Insulation is installed behind the panels and around all the copper delivery and return pipes.
• The capacity is the 4m squared in the general recommended size and with a few hours of the sun there is more than sufficient for our hot water needs
SYSTEM DETAILS, FUEL AND RUNNING COST SAVINGS [..]
• The system was self built and installed in September 2005.
• The cost of materials, tools and estimated extra cost of twin coil boiler amount to £880 including VAT.
• No labour costs have been estimated but probably 300 hours have been dedicated.
DID I THINK IN TERMS OF PAYBACK?
• My approach is to calculate a 5% return on the investment and hope that the savings of fuel use will beat this.
• I think a fifteen year payback will be acceptable. However with the certainty of increasing energy costs I fully expect that the payback will be sooner.
FINANCIALLY WAS DECISION DIFFICULT?
Not difficult because I have some disposable income and the project was spread out over several months
WAS THE SOMETHING I OR MY FAMILY DID NOT PURCHASE AS A RESULT?
No other needs were sacrificed but I feel we would do this anyway
WAS THERE AGREEMENT IN THE HOUSEHOLD THAT THIS WAS THE RIGHT THING TO DO?!
It’s a hobby as well – and keeps me active and occupied!!
WHAT I LEARNT FROM THE PROJECT
It takes longer than you think (O’Rourke’s Law). Finding suitable materials can be time consuming and there are no economies of scale.
WHAT WORKED?
Function was as expected, though I have built a previous model elsewhere so had some confidence and competence. That one has been working for eight years.
WHAT DIDN’T WORK?
• The insulation covering of one panel has been displaced by heat and sliding down a bit. It is awaiting attention and some securing screws while still allowing expansion.
• I intend to replace these cellular sheets with plain clear acrylic to get more benefit from the winter sun on the two vertically mounted panels.
UNEXPECTED KNOCK ON EFFECTS
No knock on effects. No complaints about visual effect.
WOULD I REPEAT THE EXERCISE?
I would definitely build another panel if I were to move house or make one for a relative.
WHAT WOULD I DO DIFFERENTLY?
Maybe use small bore tubing soldered on to a sheet in a serpentine pattern and save both on cost of fittings and time. This would however, require use of a pump and the associated sensors and switches.
DO I PLAN TO INSTALL OTHER RENEWABLENERGY EQUIPMENT?
I would seriously consider a photovoltaic array should there be a reasonably priced option or a kit supplied with a professional available to certify the installation for eligibility for grant and safety purposes
ANY OTHER INFORMATION?
• I have attended C.A.T. (Centre for Alternative Technology) on courses which have helped me tackle the self build. Unfortunately they seem to have stopped offering these courses due to Health & Safety regulations and the possible liability they may suffer if someone scalds themself or something.
• They do offer the courses to qualified electricians and plumbers but then you are in to market pricing of installations and able and practically minded people with little disposable funds are cut out of this essential plan for our futures.