Meeting of the solar water heater challenge with the installer Gabriel Wondraush of SunGift Solar

19.6.08

Brief outline of sungift solar as a company

Main office in Exeter and small office in Totnes, 2 fully trainer installers who work for them.

They have been going for 2 years and accredited with the UK-microgeneration scheme to allow the low carbon building programme grants and members of the solar trade association, the renewable energy assurance listing, Devon cc trading standards buy with confidence scheme.

Most schemes do checks on their work and they are complaints free.

Proud of the work they do and choosing the right components for the job and thoroughly overseeing the installation and working with the customers. They will survey each property and design each system to suit each person.

The materials they use are the best quality as most evacuated tubes in the solar industry come from china but they do not use any Chinese components. They research the components so to maximise the efficiency of each system. On the face of it solar systems are very simple, but to make the system perform well every component has to mesh with the other components. They generally aren’t the cheapest but offer good quality and good service.

After they do a survey they ask for a £500 deposit and they will guide people through planning permission (if required) and grant applications. Grants are easy now. Most systems can be done n 2 days. One day is for the pipe work and mounting the system on the roof and the second day is changing the hot water cylinder and there will be some disturbance and they leave everything neat and tidy and they then take you through the system and how it works so that you can get the best out of your systems.

They aim to install systems that will give you 60-70% of your hot water needs. So through the summer you get just about all your hot water and the winter you have to use back up heating to top up.

You will get a 10 year guarantee on the panels, 5 years on the controls and 2 years on the entire system. Once every 2 years a service of the system will be offered, the major cost is the travelling, £60-80 for the service. We can use many different panel, evacuated tubes are the most efficient, flat plate is cheaper but less efficient, and many don’t like the look of evacuated tubes, ETs work better in winter. In summer it’s more less the same for flat plate and evacuated tubes.

SunGift also do biomass systems and ground or air source heat pumps. Solar thermal is the most cost effective of all the RE technologies.

The systems they use are for the Evacuated Tubes (ET)l he is using are Thermomax They use them because they are not Chinese and they can assure the quality of the systems. Made in N.Ireland and Wales, they are mostly British panels, the tubes are made by Schott glass, and the rest of the systems is put together in the UK. They are the most efficient. Not including the discount and grant this systems usually retails at £4-5000. The cheapest flat plat is Greek, fully accredited – they are called Solex. They work with several suppliers from Austria and Germany and also the UK. They match the panels with the roof size, property size, occupancy and available tank space. The German and Austrian brackets are designed for snow load 5, which isn’t appropriate for this country. So there are lots of choices. All panels have undergone clear skys testing and solar key mark. Flat plat systems can generally start at £3300 less the discount and grant. They like to put up to 74mm insulation on the solar cylinder and like to use tall thin cylinders which help with stratification which increases the efficiency of the systems.

There then followed an extensive Q & A

Q: We already have the twin coil cylinder, can you work with that?

A: We can size the systems to the tank you have. Lots of the cost is the plumbing in the changing the tank so that will cut cost a lot.

Q: What if not enough people will come into this scheme will we still get a discount?

A: We have enough people already so we are committed to the discount. We are confident that we will get the volume.

Q: Do the tubes ever break and how easy are they to fix?

A: I have only seen three broken tubes, and two were at a school and someone threw stones at them. The other one was never working and it was a poor installation which never worked and the systems was in a bad way because of the temperature extremes that resulted. If a system has been put in well and serviced it’s no problem to change the tubes.

The tubes are self clearing(super smooth), and undergo a hail and snow load test, and then pile 1.5 tons of sand bags on , but they won’t take stones being thrown on them.

Q: Flat plane is less efficient?

A: Flat plate is less efficient.

Q: Do you use filsol systems?

A: They have been around for a long time, and they use a poly carbonate cover which gets less efficient in time. SunGift use the Swiss SPF testing reports for system performance data. And they use the systems that have the best performance/quality/cost ratio.

Q: Is the angle of the roof important?

A: The steeper the angle the roof the better it is for winter solar collection, but less so for the summer. Also East or West they get less than south, you can also do a E W system, and they are independently pumped.

Q: With the woodburner we will have to use a thermal store?

A: Yes with a woodburner we recommend the use of a thermal store if you want it to contribute to the heating. There is lots of pipe work involved and you store all the energy in the thermal store for both the hot water and the central heating.

Q: What’s the size of a 300 litre cylinder.

A: 1800 high and 600mm wide and lots of pipework.

Q: What is the difference between the Thermomax Df 100 and the HB200 does one from time to time stop working?

A: On thermomax tubes there are 2 types and one has a heat pipe which is sealed for each tube, the liquid evaporates and the other is the direct flow system. The panels will go on absorbing heat and can reach 140 degrees but this means the pump stops working. So the collectors won’t work until they go below 120 degrees. The system is in stagnation. The heat pipe system doesn’t have this problem. You can always put your boiler on however.

Q: Is there a safety problem with these systems?

A: The expansion vessel is sized to take all the liquid in the tubes. So it takes any pressure. There is also a pressure release valve. So this will automatically vent the system,. This is unusual. When a system is badly sized this can happen.

Q: I live in a bungalow will I have to have a tank in my loft?

A: Occasionally we put a tank in a loft, but we usually put it where the existing cylinder is. Tanks in a loft have to have adequate height for a header tank or be a combination or pressurised tank. So we will generally place a tank where it is, but if you want it out of the way in a loft then we can do that. We want the cylinder within 20 meters of the panels. Most of our tanks are made to measure.

Q: Survey is free?

A: Yes

Q: I have a very small cottage with an oil burner doing the central heating. Will i have to have the oil burner changed to get a grant?

A: If you have an oil stove you might want to change that. Gas? If there is gas, or if budget isn’t a problem, change it to a biomass, or Wood burner. Or you can get a high efficiency oil burner the new ones are more efficient, but if that’s what suits best?

Q: To get a grant you have done all the insulation and other things?

A: You have to tick boxes on the grant applications; Energy saving lights, thermostatic controls and insulation to cavity walls if you have them. It might not be cost effective to have to re wire your house, if you need to do that to get low energy light bulbs absolutely everywhere. You can follow the on line prompts and its fairly simple to get a grant now.

Q: Planning permission; do you need it in writing?

A: The rules changed on April 6th. If not in a listed building or conservation area, and you have a systems that doesn’t protrude more than 200mm above the roof, generally you don’t have to apply for planning. You do not need to go through the planning process. You don’t have to have it in writing anymore. As long as your permitted development rights are intact you don’t need planning permission.

Q: We had some loft insulation some time ago and it’s a very small space.

A: You don’t need it if you can’t do it economically. You can use blown in insulation if you want more insulation. This is something we can look at for you when we do the installation.

Q: How much does the Thermomax systems jut out?

A: 95mm maybe from 100mm from the roof.

Q: Can you angle the panels?

A: Yes if you want it or need it, but generally we don’t do it, unless you have a flat roof, most roofs are at a good angle to collect sufficient radiation.

Q: Can I have a Photo-voltaic pump?

A: We can use Photo voltaic (pv) pump but it increases the cost of the system. It will make the system less efficient, and the controllers can be better if they are run on the mains. There is lots more flexibility. PV pumps will add about £400 to the cost of the systems.

Q: If there is a power cut?

A: They won’t work if there is a power cut if you are on the mains.

Q: Hot water is what % of your energy bill?

A: Hot water is 25% of your total energy bill and the thermal systems is 60-70% of your hot water needs.

Q: I use off peak electric for water heating. During the day the panel will heat up the water and the night the electricity will?

A: The solar will do the work during the day, and if the desired temp is reached, then you won’t use the electric. But if you take a bath during the evening then you will use the electric more of the time. So it depends on your bathing habits as to whether you get the most out of your solar system.

Q: Combination boiler?

A: With combis if the boiler accepts the pre heated water and it will then use it. If you are below the temp the boiler will heat it. But you can convert the boiler into a non combi boiler. We then have to use a tank.. Horizontal cylinders are 30% less efficient.

Q: Are there minimal or very basic systems?

A: Yes there are Thermo siphon systems. They have no controls and we can sometimes use second hand panels, but we can’t guarantee the panel and the connections can’t be guaranteed. They will probably be £2500 less discount and grant.