Case Study

This domestic solar water heating system that won the Green Apple award, was installed in Edgware, Middlesex, England by SolarBase and the equipment was supplied by Navitron:

Introduction

As gas & electricity bills continued to creep up the home-owner got fed up with it and decided to do something constructive to reduce his expenditure on energy cut down our CO2 emissions at the same time by installing a solar water heating system.

Background & Objectives

4-bedroom semi-detached, solid brick built in the 1930’s with a large kitchen extension, conservatory, study and a bedroom extension in the attic with 3 occupants, with icos-Ideal H24 condensing gas boiler for hot water and central heating with wall-mounted radiators.
No cavity wall insulation possible/applicable, south-facing property, solid brick built.
This particular householder spends about £2448 per annum on gas & electricity, or about £204 per month (payable by direct debit), which is considered excessive.
The energy saving from solar water heating is expected to enable almost a cost-free consumption of hot water between April and September (based on similar installations) whereby the boiler may be used very little for about 6 months.
During the rest of the year, it is estimated that the solar water heating will contribute about 10% in hot water energy saving.
 
Issues & Challenges

This solar water installation was particularly challenging because the flow/return pipes had to be routed and secured to the external wall roof structure leading from a flat roof of the loft conversion.
The solar water heating panel was located on top of the 4th bedroom extension on top of the attic and all other components had to be fitted into the airing cupboard with little space to manoeuvre.
Due to this reason the specially designed and built hot water cylinder was sized as 300 mm diameter (350 mm including insulation) by 1500 mm high (144 litres total capacity).

4 Years' Return on Investment & Subsequent Savings

• Cost of the solar system was just under £3000.
• Cost of 55 electricity saving (CFL grade B) lights was about £350.
• Cost of window curtains to reduce drafts was about £150.
• Cost of a magnetic gas-economiser device was about £60
• Total outlay was therefore about £3560.
• The solar installation was expected at best to save about £50-£60 per month (about £600-£700 per annum), or about 35-40% of the total gas & electricity bill.
• In practice, the solar hot water system, combined with other energy saving measures has saved £900 per annum, thus exceeding expectations.
• Return on investment should be; £3560 divided by £900 = 4 years, and the saving for the next 15-20 years thereafter is expected to be around £15,000.

CO2 Pollution Reduction

Before the solar water heating system and additional energy-saving measures, the house produced approximately 5.46 tonnes of CO2 annually and after the installation pollution was reduced to 3.01; an annual reduction of 2.45 tonnes, or 45%.
Can you imagine 1 million, 10 millions or 100 millions of homes improved like this one?
The benefits from cutting CO2 pollution will be huge, running into millions of tonnes!
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