These are twelve thought provoking tips from Gabriel and Colin. Now that the renewable heat incentive (RHI) is imminent, it is particularly important that people who now decide, perhaps as a new year resolution: "I want to buy a solar panel for water heating in 2011" have all the fact at their fingertips when they make a buying decision. So here are five further tips for people who are thinking of buying solar water heating:

13/ Some actually prefer the convenience and interactivity of rapid, low-obligation telephone solar quotations which are typically conducted using aerial photos of their roof with the help of a detailed but simple questionnaire. We have been doing these "eco-surveys", very accurately, but admittedly for relatively is simple zero carbon retrofit installations, for the past twelve years. Our trained graduate surveyors rarely make a mistake, thanks to carefully crafted questions and solar inquirers who are, in fact, able to answer their questions well.  But if there ever is a mistake, then we pick up the bill for any extra costs anyway. Remote surveys based on what the customer knows: what floor is your hot water store on? can you email me a photo? etc, is a super green way to eliminate vehicle emmissions from the sales and survey process, where this is possible.

14/ Some people want to know whether their solar thermal installation will put up their electricity bill. Even if a mains pumped solar water heating systems only costs £10 extra a year to run, it will typically to negate its carbon savings by about 20% according to both DTI and Energy Saving Trust funded research.

15/ Others plan ahead, asking about regular solar water heating system maintenance requirements such as for antifreeze (not always required, this usually needs replacing every few years at a cost which can over £100), water softeners (which can cost around £10-£20 per person per year to run with most non-antifreeze based, water filled systems, and high pressure hot water cylinder inspections (some of which should be checked annually by a G3 qualified plumber every year, at a cost of around £100). Extra costs  erode the savings you make from solar water heating energy savings and your RHI income.

16/ Some solar water heating systems require users to replace their hot water cylinder with a costly new one. Several do not. Some installations comply closely with HSE requirements on Legionella, others less so. Some installations, called retrofit installations, re-use the existing hot water cylinder. This generally means a rapid one-day installation with no hot water loss overnight. Most retrofit solar heating installations are designed to "back-up-heat" to the hot water cylinder base daily. Most new "solar cylinder" installations do not heat to the base. Installations which do not heat to the base may deliver about 10% more solar energy, but at the price of a tenfold increase in Legionella risk, according to our calculations. Is this avoidable increase in safety risk is acceptable for state funded installations under RHI in UK? This question is now under review via the Microgeneration Certification Scheme.

17/ The legionella-safest of all solar water heating installations are called thermal store installations. These can provide high pressure hot water as pre-feeds to combi-boilers, for example. Having installed several thousand solar water heating systems, these are increasing in popularity to the extent that about half our installations at present are thermal stores.

I hope these extra solar heating buyers guide type tips, based on our experience as innovators in the zero carbon solar retrofit area are helpful to readers!

 Regards, Barry Johnston.

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An excellent summary. I would add a couple of further points.

Firstly, that people should look for installers that are members of the REAL Assurance scheme, which explicitly bans the pressure sales tactics you refer to. The code also covers other areas of consumer protection.

Secondly, that they should look for testimonials, and ask to speak to existing customers.

Colin Newlyn
Ecohouse Solar

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