Wind Turbines
We have invested in our own turbines in Hertfordshire to evaluate the different machines available to allow us to provide our customers with accurate advice. This has now grown to Touchwood in collaboration with Segen Ltd becoming registered site surveyors and installers of small wind and PV systems - suitable for the domestic, school and farm scale.
The turbines we survey for and install are ones we would recommend ourselves. Below are the machines we offer with their corresponding blade diameter size, please click on the turbine name to see the full datasheet;(under construction!)
- Kestrel 1kW. 3 meter blades.
- South Western Wind Power Skystream 1.8kW. 3.7meter blades.
- Iskra 5kW. 5.4 meter blades.
- Westwind 10kW. 6.2 meter blades.
- Westwind 20kW. 10.4 meter blades.
It is important to remember wind energy unlike PV is non linear - in that power produced is proportional to the cube of the wind speed and the square of blade diameter. So a doubling of blade diameter results in 4 times the power.
PV systems on the other hand are linear, meaning that doubling the size of the system will produce double the power. The result of this is that the larger your wind turbine the exponentially better the power produced, and thus pay back period.
We would never be associated with building mounted turbines - the technology does not scale down well (due to it's non linear nature), meaning a turbine small enough to be safely mounted on a building's wall would never be large enough to produce a significant amount of power. It is also worth noting that the smaller the turbine, the faster the rotation speed, so small ones with around 1 meter diameter blades not only produce very little power but make more noise.
Larger machines are also available on request for farm / industrial unit situations. for more information please email:
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Photovoltaic Panels
PV panels make electricity directly from the sun, and can make a considerable amount of electricity. PVs are suited to sites where wind energy cannot be used such as built up urban environments where the wind resource is poor.
Touchwood have our own 2.88kWp PV array on our show home which we have been monitoring to see just how effective the technology can be. The system has produced around 2600kWh in a year, a substantial contribution to a households typical annual usage of around 5000kWh/year.
PV arrays can be roof mounted, ideally on a 45 degree pitch south facing facade, or we can now install ground mounted systems for locations where no suitable roof area exists - as seen in the picture. A flat roof is also a good option, since PVs can be installed on a stand to provide the ideal 45 degree pitch to the sun.
A site with PV and microwind is ideal since they complement each other very well - in the windier winter months there is less sun, and in the summer the reverse happens - therefor together the technologies will produce electricty most of the time
Touchwood can now survey your site for a PV system, supply and install the system working with out partner Segen. Various size grid connected systems are available to suit most situations. For more information please email:
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Heat Pumps
We have worked on the installation of heat pump systems and would not recommend their sole use due to their Achilles heel - essentially they are electric powered heating. A good heat pump system can be up to 400% efficient (i.e. 1kW electricity produces 4kW heat) but this is heating by electric - often quoted as the worst environmental heating method since grid electric is so massively inefficient. If you are producing the electric on site though, through wind or PV then this problem is removed and heat pump technology is worthwhile.
We think it is much more sensible and cheaper to firstly super insulate a building to virtually remove the need for a heating system and then have a wood fuel back up heat source for those very cold days. A simple cheap log stove would do this.
Solar Panels
Solar panels on the roof are another fantastic technology that will produce big savings on hot water. With these systems the sun heats the panels, which then heat the water. This hot water is then pumped to the hot water tank ready for use in the house. During the day this process can heat all the water in the tank thereby eliminating the use of the back up heater. We have installed many solar systems and know the techniques to provide an efficient system. A large hot water tank is needed to store the day's heat energy, evacuated tubes are best to avoid lime scale damaging the panels, and an intelligent dynamic controller is essential to maximise the energy saving potential.
Heat Recovery Ventilation
Using our logging software we can now see the effect on a building's temperature of a HRV system through performing runs with and without the system operating. The HRV will level out the temperature on each floor of the building and keep the air fresh by heating incoming air with the stale air leaving the building.
This graph shows how the production achieved from the 2.88kWp PV and 5.00kWp Wind Turbine compare. The PV was ahead in the first few months but then the turbine's production has increased throughout. Note that the PV developed a fault during December which is why no figures are available since. We have been promised this will be fixed in April!
