Questions and Answers
1. What are the differences between flat plates and evacuated tubes and why would one be better than another?
Evacuated Tubes. Good quality vacuum tubes manufactured in a country with a history of tube technology such as the U.K. are better in winter as there is no heat loss due to the absorber plate being in a vacuum. Tubes are smaller and lighter than flat plates making them easier to fit with less weight on the roof. Tubes usually work out to be the same price or less than flat plates, not per square metre, but per installation on a domestic property.
Thermomax tubes are made in the U.K by a British company, so less Co² produced in transportation. Thermomax is the oldest tube manufacturer in the world with a reputation for efficiency, strength and reliability. The tubes simply plug into the manifold and are inexpensive and easy to replace, costing £40 -£50 per tube compared with £500 – £700 for a new flat plate collector if it was damaged. Realistically, any damages are highly unlikely.
Tubes do not require an ‘A’ frame when installed on a horizontal surface i.e. a flat roof, thus avoiding wind-lift and making them less obtrusive. They can be installed horizontally directly onto a wall with the tubes twisted towards the sun at the optimum angle. In the same fashion they can lie flat onto a flat roof without an ‘A’ frame. One collector is always sufficient for a south east or south west roof, therefore only one set of fixings and less pipe work on the roof. They do not corrode. Tubes take less energy to make, less materials, there are no problems with condensation, snow slides off easily and they work in freezing conditions. They are 100% recyclable, hail proof and built to withstand substantial snow load.
Thermomax is the first evacuated tube manufacturer to gain a world market and has been manufacturing for nearly thirty years. We have installed them for 23 years and expect them to last at least 25 years plus.
Flat Plates have been well proven over the last 100 years or so. Life expectancy is 20-30 years and they can look very similar to Velux windows being ideal for roof integration, which is often better for listed buildings and conservation areas. They are not as efficient as tubes per square meter and therefore you will need to install a bigger surface area to heat the same amount of water. The rule of thumb is that for 3m² of absorber area in tubes you need 5m² of absorber area in flat plates to heat the same amount of water. Normally we would install them at an angle, either on an angled roof or mounted on an ‘A’ frame.
2. What components do you normally install? Why do you recommend these products over other ones? Are these products included in your tender?
We install different products to suit different requirements and it is very rarely that we come across a house which is not suitable for a solar installation.
DF100 – Direct Flow tubes are low cost and good for flat roofs and walls. HP200 – Heatpipes are for people who want the best output and the only collector with a Memotron (memory metal) valve which shuts off the tubes and never allows them to heat beyond 95 ºC; no stagnation; better for system.
EWF flat plate collectors for roof integration or because the customer prefers the way they look.
Resol controllers. Easy to use; half a million units have been sold and they have been on the market for 30 years.
Kingspan cylinders. Kingspan, owners of Thermomax, is the biggest company in the U.K making a large range of cylinders at good prices with good specifications.
Wilo circulating pumps are used as standard.
Laing pumps. These pumps use 9 watts compared to the 35-55 watts of a traditional circulating pump. Laing pumps are an optional extra.
All these products are all included in the tender, except Laing pumps.
3. How do you size the hot water cylinder? How much variation does this make to the cost?
We use 8 – 12 litres of storage per tube, for example: a 166 litre twin coil cylinder with 20 evacuated tubes.
We use a larger cylinder, 50 litres per m² of absorber area, with EWF flat plates – the cylinder costs £50 extra for 50 litres more storage, or, £1 per litre.
4. What is the extra cost of an east/west installation likely to be over a south facing roof slope?
East/west systems require extra plumbing, a controller upgrade, an extra pump and flow meter, 2 x air vents and 2 x collectors plus labour. This means £400 – £600 more depending on the size of the system.
5. Have you done wall-mounted installations before? How effective are these compared to the roof mounted?
An evacuated tube collector mounted flush onto a wall needs to be 20% bigger than the same mounted on a south roof.
1-2 people – 20 tubes
3-5 people – 30 tubes
We can install an ‘A’ frame for both tubes and flat plates. We have around 20 domestic systems with panels mounted horizontally on walls. For photos and more information please see our website: www.solarworks.co.uk.
6. In the (unlikely) event that a household had a complaint what steps would you take to resolve it?
Our complaints procedure is as follows:
Customer Care After Installation
The customer is phoned a day or two after the installation to check that all is well. Upon completion a Customer Satisfaction sheet is handed to the customer to be returned after a month. 5 yearly system checks and anti-freeze changes are recommended.
Fault Rectification
A free customer help line is available from 8am – 8pm, Monday to Friday and 9am – 5pm on Saturdays – 0800 7814004. At all other times, an answer phone service is available and regularly checked.
The phone is manned by family members trained to identify faults, give advice and arrange repair work to be carried out within a time scale determined by the nature of the fault.
All new system faults are dealt with within 48 hours and mostly sooner. These faults are generally minor.
In the case of a severe fault an operative is sent out immediately and can arrive in Wenhaston, allowing for traffic and hold ups, within 2 hours.
We believe in admitting to our mistakes, saying sorry and sorting out the problem. We are a family company. We don’t want to take problems home with us!
All products and installations comply with relevant BS/EN numbers as per Low Carbon Building Programme requirements, CE131 and MS001. Building Regulations parts L and G, Standards 6 and 4.9, Parts F and P. Water Supply Regulations 1999. Water fittings Bylaws 2000.
All components are checked before leaving our Lavenham workshop and pumping stations are assembled by Solarworks employees, ensuring quality and compatibility.
If a component fails the batch number has been recorded by us and it is returned with the faulty product to the manufacturer. We then make a judgement whether we can trust that this is a quality control issue on the part of a manufacturer whose products have been tried and tested by us for years, or, whether this is a faulty design from a product we are not familiar with. If the latter is the case any remaining components of the same ilk are set aside until we ascertain whether or not they should be used or sent back. Any components which have already been installed will be monitored.
a) By a phone call to the customer
b) Through physical investigation by an installer
If a product failure is identified with this product or batch then Solarworks will replace them all free of charge.
7. How long is the work guaranteed for and when, if at all, should households expect to replace the panels / tubes?
A two year parts and labour warranty
A five year warranty on collector components
In 25 years Solarworks has never had to replace a collector, flat plate or tubes. We have sold 13,000 tubes in the last year, and warranty claims have amounted to 10 – 20 tubes, due mostly to a broken tube in the box during transportation. The life expectancy of Thermomax tubes is 25 years plus and good quality flat plates, 20 to 30 years.
8. How many installations have you done in the last two years?
We have completed 160 installations in the last two years, ranging from 10 tube systems for one person households to 160 tubes for commercial customers. We supplied 20,000 tubes, or, 1000 systems with some going to South American countries, African countries, new Zealand, France and Spain.
(1 x system to the British Antarctic Survey Team in 2000 followed by another 3 x systems in 2007 – which we are particularly pleased with! After the first order they bought a Chinese collector which was destroyed by the extreme weather)
9. Have you been involved in any sort of projects such as this before?
Solarworks has been involved with several grant schemes and installations for Councils and Housing Associations:
Braintree D.C. – Social Housing with performance monitoring 2003
Sole contractor for Braintree grant scheme 2004 –2007 – 27 houses
Sole contractor for Southend -On-Sea grant scheme – 50 houses
Suffolk Housing Association – 32 flats
Others include:
Solar for London, Circle 33 Housing Association 6 flats, Surrey Housing Association 22 flats, E.C.S.C. Surrey and Kent Scheme, Surrey Solar Club, Affordable Energy – Essex E.E.E.A.C., Suffolk S.E.A.L., Energy for Good Cambridge and Ely, C.E.N. Scheme – Sussex and Kent.
10. Question: What geographical area does your business cover?
Answer: East Anglia, London and the Home Counties, with accredited installers nationwide.
11. Question: If ten households wish to go ahead what is the timescale for the installations? How long does one installation typically take and how would you propose to manage the process and would there be any extra inconvenience to households by having to link up with others?
Answer: The time scale is 4 – 5 weeks from order to completion. Installations take two installers between one and one and a half days. We have six installers with a combined experience of 85 years. Each installation will be completed by a two man team before they move on to the next house.
12. Question: Do you ask for an up-front deposit and if so how much?
Answer: A 10% deposit will be required; signed contracts come with a 7 day cooling off period as per Solar Trade Association Code of Conduct and REAL Assurance Scheme, both of which we are members of.
13. Question: When do you expect to get your MCS registration? Have you got an inspection date for accreditation?
Answer: Microgeneration registration took place in January and an inspector will make an appointment with us soon, although they have not yet set a date. Solarworks is a Clear Skies Approved Installation Company and a Low Carbon Building Programme Approved Installation Company.
14. Question: What is the impact of a solar heating system on the choice of boiler since we expect to renew our boiler in near future?
Answer: No problem as long as you do not choose a combination boiler.
15. Question: How is the system protected from over heating?
Answer:
The HP200 evacuated tube has a memotron valve to switch it off at 95°C.
DF100 heats up to 150°C the same as all other collectors including EWF flat plates so an 18 litre expansion vessel and a 6 bar safety valve is fitted for safety.
When the cylinder has reached the temperature it is set to the controller switches off the pump and the steam in the collector and pipework goes into the expansion vessel where it remains, condenses and returns to the pipework once the cylinder again requires heat.
The system is self regulating. There is no manual intervention required by the user so for instance if you go on holiday simply leave the pump and controller switched on and leave happy in the knowledge that the solar at least will look after itself.
16. Question: The orientation of our house is SSE, could we mount panels on a on a slate roof facing in this direction? We are less keen to have wall-mounted panels on the gable end because of limiting future sunroom options.
Answer: Any orientation within 45° of south is fine. With tubes you can turn the absorber plate 20° by twisting the tube the way you want it to face in order to maximise the absorber plate’s exposure to the south. This will mean that an evacuated tube collector on your south east roof is likely to face due south.
