OUR CONTACT POLICY
We endeavor to provide as much information as we can.
To keep costs to the customer to a minimum we do not operate a call centre.
If we can help it is by far easier for potential customers to list any queries in an e-mail and we will attempt to provide information on a point by point basis.
Unfortunately we simply don't have the time to act as individual project ‘consultants’ free of charge – many solar system providers would charge a small fortune for advice or incorporate their 'advice charge into their costs'. We receive numerous information requests on a daily basis this is why we incorporated as much information as possible into this website. Most queries can be answered by taking a little time to refer to the site and the downloadable information available.
In the past many individuals and organizations have merely used us for technical information, which in most cases they could not obtain elsewhere without expense, provided at our expense in time and effort. We have learned from this and policy had to change accordingly - hence the detailed information made available on our website.
Unfortunately we simply don't have sufficient time each day to discuss numerous similar queries over the telephone or we would not be able to concentrate on our core aim which is to supply low cost solutions for the DIY alternative energy market.
PLEASE ALSO CLICK HERE TO CHECK OUT OUR PAGE ON PRACTICAL APPLICATIONS OF RENEWABLE ENERGY
SOLAR
Collector dimensions?
The 10 tube double-walled tube collector (47mm tubes) is 1760x 760 x130mm (LxWxH)
The 20 tube double-walled tube collector (47mm tubes) is 1760x1500x130mm (LxWxH)
The 30 tube double-walled tube collector (47mm tubes) is 1760x2170x130mm (LxWxH)
The 20 tube double-walled tube collector (58mm tubes) is 1900x1660x200mm (LxWxH)
The 30 tube double-walled tube collector (58mm tubes) is 1900x 2406 x200mm (LxWxH)
The 10 tube single-walled tube collector (70mm tubes) is 1760x1000x130mm (LxWxH)
The 20 tube single-walled tube collector (70mm tubes) is 1760x 1950 x130mm (LxWxH)
Handle with care?
The tubes are made from borosilicate glass, which is very tough,also known as pyrex. The tubes are designed to withstand hailstones up to 35mm - so they are unlikely to be broken, unless dropped onto a solid floor prior to installation. The 58 mm tubes are notoriously difficult to transport. 47mm tubes 'travel' better. We still recommend that you order 3 spare tubes with every order to offset the possibility of any damage in transit.
When assembling the panel kit don't overtighten the jubilee clips over the rubber boots and tubes as this may crack the glass and render the particular damaged tube useless:
It is important not to over-tighten the circlips around the rubber boots when fitting the tubes to the panel. To over tighten may eventually result in the end of the tube cracking off.
If you over tighten you risk cracking the glass tube - the air/moisture will react with the black coating - aluminium nitride, but it is a slow process - it takes between 2 weeks (badly damaged tube exposed to wet weather) and 12 weeks (small crack/summer weather) - this always tends to throw people. If damaged at the time of installation - it would not start to discolour for several weeks, so people do not realise that it has happened. The other main culprit is over tightening the jubilee clips - particularly if they are installed in colder weather, as the pressure on the glass will increase when the tube/weather gets warmer. It will be obvious when removed - it will be a circular or semi circular crack underneath the jubilee clip – a precaution is to rotate the tube as you are installing, as soon as there is some resistance, stop tightening. And always use a screwdriver rather than a ratchet wrench or drill driver. Be careful remember in some cases when it comes to tightening less may be preferable to more!
Solar cylinder sizing for my requirements?
It is a suggestion that the 20 tube panel is used with cylinders up to 175 litres.
The 30 tube panel is suggested with cylinders up to 260 litres.
If your cylinder is larger then it can be heated with more than one panels. It is possible to add an extra panel if you aim to benefit from higher temperatures in the wintertime.
If you decide to fit a smaller cylinder you will get hotter water however less of it. You might consider fitting a small tank of 135 litres if you only need a smaller amount of hotter water.
Panel output in terms of kWh?
This depends upon the time of year - in summer you would expect almost 10 times more solar energy that we get in wintertime.
In the mid summer you might expect to get 14kWh of heat per day from a single 20tube panel. In December this could average only 1.15kWh per day. In winter it is still possible to preheat water to 40C or greater in the winter sunshine. If multiple panels are fitted then it is possible to heat water to 100C in January (This has been achieved in Cornwall).
How hot will the water get?
This depends on the size of the cylinder you choose and the amount of water you use. A smaller cylinder will heat to a higher temperature, whereas a larger cylinder will heat more water, but not to the same extent. Systems are generally designed to heat water to 65C or so, although during the winter, it may be necessary to 'top-up' the heat on less sunny days. Large arrays, running high temperature solar antifreeze at high pressures can be designed to achieve temperatures of 170C or more!
Where do these need placing and at what angle?
Panels should be sited on a south facing wall or roof. In fact, anywhere between South-West and South East will give good results. If you are limited to an East-West facing system, then you will need two panels to provide the same amount of hot water as a single south-facing roof slope. The most frequent solution to this problem is normally to mount one panel on the east slope and a second panel on the west slope. A special controller is available for East/West facing installations.
The panels should be mounted at the angle of your lattitude. For example, at our location in the UK, this is 53°. This is AVERAGE optimum angle. In fact, in winter the optimum angle is 15° steeper, whereas in the summer it is 15° shallower. The panels will function anywhere between 15 and 90° angle of inclination. This is actually academic, a variation of 15° will make very little difference to the output, so most people simply settle for whatever angle their roof slope is. The extra cost of trying to stand panels off the roof to achieve better efficiency would probably be better spent on purchasing a second panel!
Does the roof need to be strengthened at all?
The solar panel in operation weighs around 50kg - this is really not much weight for a roof, when you consider the weight of the tiles or slates. Generally there is no requirement to strengthen a house roof prior to mounting the solar panel, except if you are fitting a panel to a very old roof, which has sagging and decaying timbers.
Are spares available?
Yes, spares are always available, should you need them. With no moving parts, it is very unlikely that you will need to replace anything, but occasionally customers break tubes during the installation process, in which case you can purchase a modestly-priced replacement. However, it is not possible to post a replacement tube, so you will need to collect it. The tubes are made of borosillicate glass (aka 'pyrex') so they are actually very tough.
Can I fit this system DIY?
Yes you can! These systems are very easy to fit, and anyone with basic plumbing and electric skills can carry out a DIY installation. Mounting the panel on the roof is sometimes daunting, although it is actually quite simple - but we can offer this service, if required.
How do I connect both ends of the panels manifold 22mm to the 15mm recommended pipework?
Fit to both ends of the manifold using compression joint pipe connectors a 22mm copper elbow with reducing olive down to the 15mm pipework. (available from plumbers merchants/suppliers).
How do I fill the solar loop?
To fill the solar loop, premix the antifreeze/water to 40% concentration in a 'hanging basket watering device' available from any garden centre. Remove the nozzle/lance of the device - there should be a threaded connector. You will then need to obtain an adaptor from a plumbers merchant to adapt this to the filling loop supplied with the pressure system kit included within your solar kit. (Depending upon the watering device it is something like a BSP 1/2 to BSP 3/8 male/make adaptor). You can now connect the watering device to the filling loop, via the non return valve supplied in the pressurised system kit and by pumping the handle to pressurise the reservoir, it will force the antifreeze solution into the system. Ensuring that all air is bled out of the highest point in the system (usually by loosening one of the compression fittings on the panel itself) once the air has been bled tighten the connection which has been used as the bleed point. Continue to fill until the pressure reaches 1bar, the 'pressure system kit' includes a pressure gauge. After the first hot day, when any air in the system will have expanded, repeat the bleeding and pressurisation procedure to 1 bar. You could also repeat the process a month later just to ensure all of the air had been bled from the system and you are getting maximum benefit!
Can I come on a course to learn how to install solar water heating systems?
Yes you can! We run training courses every month, which are designed to run through everything you need to know, whether you are planning to DIY, or become a professional installer.
Will the system need to be inspected by a plumber or be installed by a plumber?
No, you can do this yourself. However, you can call in a plumber to carry out the work if you feel you are not able to tackle to plumbing yourself.
We normally recommend that you fit a pressurised system. This is not essential, but it allows you to place the solar panel on the roof without worrying about whether it is possible to place the header tank high enough to function correctly. With a pressurised system, the plumbing is simpler, and by running the system at 1-2 bar, it is possible to increase the boiling point of the water to 120C or higher - allowing greater safety margins, and lower chance of fluid loss.
How much maintenance do the systems require?
Very little maintenance is required for solar water heating systems. You should occasionally check the system pressure, to make sure there has been no water loss, and to check for any air in the system. The only other requirement is to ensure that there is an electricity supply connected at all times, otherwise without pump circulation, in strong sunshine, the panel could overheat, and start to boil off water.
What about freezing in Cold Weather?
The solar panel is very well insulated - the manifold is surrounded by 2"of rockwool insulation. This is better than your outdoor water pipes, so it is unlikely to freeze except in exceptionally cold weather. However, it is recommended that you take precautions to prevent the possibility of freezing, by either adding antifreeze to the system (use a non-toxic solar antifreeze) or you can use a DELTASOL B controller which has 'freeze protection' - this controller monitors the temperature of the collector - and if it falls below 4C, it will turn on the pump, allowing water to circulate and heat the manifold. You should turn this function off if you use antifreeze.
Can I use Solar Power with a Mains Pressure Hot Water Cylinder?
Yes. There are two ways to achieve this. You can either purchase a mains pressure unvented water cylinder (these can be expensive). Please note that you will have to have a pressure vessel certificate to install these. Alternatively, you can fit a 'solar store' cylinder (see below)
What is a Thermal Store?
A thermal store is a tank which has an additional large surface area high efficiency coil fitted. The mains cold water is fed into this coil, thus heating the water on its way through. The mains water exits the tank as hot as the hottest water in the tank, but without losing any pressure - thus providing mains pressue hot water to the household taps.
Can I get a grant for these systems?
Grants are only available for professionally installed systems. At the moment, the panel is undergoing testing for the solar grant. However, this will take several months, and costs in the region of £15000. The government has refused to allow a UK laboratory to carry out the required tests - so we are forced to use labs on the continent - which pushes up the cost of the exercise. Once we have carried out the required tests, the price of the panels will have to increase to cover the investment. For this reason, it is likely that the grant will not make the solar installation any cheaper. Solar installations are available at £2500, whereas the grant-aided systems are generally £6000-8000, with a £400 grant!
Do I need planning permission?
In most cases, no. Evacuated tube solar panels are considered in the same way as roof windows. Unless you live in a listed building, it is unlikely that it will require planning permission. Even if you do live in a listed building, you can usually fit the panel to the rear of the building, or at ground level without requiring planning permission
Can I power the pump with solar energy?
Yes, this is possible. For flat plate collectors, manufacturers will specify a 5W photovoltaic panel, and a 5-10W low voltage pump. This is because flate plate collectors do not work efficiently in low sun conditions, so the pump only needs to function in bright sunlight. This is insufficient for evacuated tubes, which due to their high efficiency, will require pump circulation even in overcast conditions. For this reason, the pump should be rated at least 10W, and the panel 20W to provide sufficient circulation. At the moment, there is no cost-effective low voltage pump on the market suitable for pumping hot water. The most popular 12v solar pump, the 'ivan' retails at around £150-200, making this an expensive option. It is possible to use a solar photovoltaic panel to drive a mains inverter, powering a standard 220v circulation pump, but most customers do not want the complexity of such as system.
What is the difference between the single-walled and double-walled solar panels?
The difference relates to the design of the solar tubes. The standard tubes are double-walled, with a vacuum between the two walls of the glass. The centre is filled with air and the heatpipe runs up through the centre. The single walled tube is entirely filled with vacuum, and the vacuum is sealed by a glass-metal weld sealing the heatpipe to the glass. This is technically much more difficult to do, hence the cost is much higher. The single walled tube has a marginal advantage over the double-walled tube in that it reacts much quicker to sunlight (eg it starts to heat water within 5-10minutes rather than 10-15minutes) - so it is slightly more efficient in marginal conditions. However, it also cools down quicker, whereas the standard tube will continue to heat for 10-15minutes after the sun goes in. A 10tube single walled panel (70mm diameter tubes) produces about 10% less heat than a standard 20tube double-walled panel (47mm diameter tubes).
How many panels/tubes do I require to meet my household needs?
This is a difficult question to answer as it depends on your water usage. For example, one person that contacted us lives in a motorhome, and uses only 70litres of hot water over a two week period. A young couple I spoke to estimated their hot water consumption to be at least 400litres per day!
First you should calculate how large a hot water cylinder you require to meet your needs. Remember that solar cylinders are normally designed to store water for use over 2 days, rather than one, thus allowing you hot water even if the following day is cloudy. Once you have calculated your cylinder size, you can estimate your panel size on the basis of One Solar Tube per 6.5 - 8.5litres of hot water cylinder (i.e. a 20tube panel can supply hot water for a 120-170litre cylinder, and a 30tube panel can supply 180 - 255litres). This assumes you have an unshaded south-facing roofslope to mount the panel
Can I heat my house with evacuated solar tubes?
There is 10 times more sun energy in the summer than in the winter. (this is the reason for the different seasons, after all). Therefore you immediately have the problem that the bulk of the energy is at the wrong time of year. The other problem with using solar to heat your house is that it is not present at the times when it is really cold - at night, on very overcast days, in winter evenings etc.
In practice you can provide a significant amount of supplementary heat in the spring and autumn (and some people have implemented such systems), but the contribution in the winter will be minimal, restricted to sunny days, but you will need to fit many more panels, as heating a house is a lot larger task than heating an insulated cylinder of water. Solar water heating on the other hand, can be effective even in the winter, as the amount of heat required is considerably less than that required to heat a house.
WIND
Are these prices for real?!
Yes, these are real prices! I think you call it 'ethical pricing'! It is a full kit - the only thing you will need apart from this is - batteries (I can supply 110Ah deep-cycle batteries for £69),
battery hook-up wires and cement for the foundations. These wind turbines are extremely good, and I have sold a lot in the UK. Unfortunately, as there are a lot of over-priced wind turbines for sale, it seems too good to be true - so if you are thinking this, feel free to come and have a look at the turbines before you buy - you can take one away with you if you decide you like it.
What the dimensions for the various turbines?
The dimensions are as follows:
200W 2m diameter, 4m tower
300W 2.5m diameter, 6m tower
500W 2.7m diameter, 6m tower
1kW 3.0m diameter, 6m tower
What power wind turbine do I need to power my house?
How do I know?! It depends on the wind available and the amount of electricity that you use. Neither is something that I can determine. I can provide some guidance however - click here for more details
Do I need planning permission?
Planning requirements vary from one area to another. Most planning departments will require planning consent for structures over 4m high. However, planning should not be required for temporary structures - and many people have successfully argued that a tilt-up tower (as supplied by Navitron), is a temporary structure, as it can be lowered to the ground when not in use. The same applies for mounting the turbine on any kind of moveable structure, such as a trailer, light gantry, cherry-picker or forklift.
If planning consent is sought, it is normally granted without problems, and we can help with the wording of planning applications, if required.
Approximately 95% of customers do not bother with planning permission, and this does not normally cause problems. You can always apply retrospectively, if required to do so.
Where should I site the wind turbine?
The turbine should be sited far enough away from living and sleeping areas so as not to cause disturbance. Consideration should also be given to neighbours in this respect - after all, they will not be reaping the free electricity from the wind turbine! Generally the wind turbine should be at least 6m (for 4m towers) or 8m (for 6m towers) from the house. To ensure safety, the tower should be sited away from buildings, cars and play-areas etc. so that no damage will occur to property if the tower should fall for any reason. You should not allow anyone to come within 7m of the tower whilst the wind turbine is operating, or during windy weather, for safety reasons. Some companies advocate mounting a wind turbine on a rooftop or gable end. This is strongly discouraged by most installers for the following reasons: vibration will carry through the building structure and exaggerate noise inside the building; the building structure may be weakened by constant vibration, unless a very small turbine is used; planning consent is much less likely for roof-mounted turbines and the turbulence associated with a roof will reduce performance and lifespan
In terms of performance, the wind turbine should be mounted in an open position away from trees, buildings or any other structures. The turbine should be mounted as high as practical, and with clear views to the prevailing wind. If possible, the turbine should be located on a hilltop, or ridge on the side exposed to the prevailing winds. Not all locations can provide ideal positions for wind turbines, but even theoretically poor sites can yield adequate results, although you may experience lower outputs.
How much noise do these make?
Wind turbines are not silent, but nor are conventional power sources (think of petrol or diesel generators!). The wind turbines make a swishing noise, caused by turbulence around the blades. This is not particularly loud, and often the noise of the wind itself and of trees buffeting in the wind is louder. However, in strong winds, the turbine can create a whistling noise - so it is not a good idea to site it immediately next to the bedroom window, however, with double-glazing, it is unlikely that you will hear the turbine inside a building 10metres away.
The survival wind speed (40m/s) seems low
Actually this is quite fast - it is equivalent to 90mph. This is the highest inland wind speed ever recorded in the UK. However most wind turbine failures are caused by gusts rather than constant high speed wind - often gusts will be far faster than the measured wind speed, and often come from a completely different direction. For customers in very windy areas-particularly on the coast in exposed locations - may consider this survival speed too low. In such circumstances, it is possible to trim the blades to a shorter length, which will reduce their performance in low wind speeds, but it will allow the turbine to withstand higher wind speeds without damage. It is important to bear in mind that these turbines are low-wind speed turbines, which in average UK winds, outperform wind turbines from another British manufacturer rated at 4 times higher power!
Can I get a grant for these systems?
In order to get approval for the government's so-called grant scheme, it is a necessary for us to spend £10 000+ getting the wind turbines approved. If we do this, the price of the wind turbines would have to be increased substantially to cover the cost of this approval. When the government have issued little more than 200 grants in total, it seems that these grants are not that readily available! DIY installations are specifically excluded by the grant scheme, so you would be looking at spending £15 000+ to qualify for a wind turbine grant!
Can I connect the wind turbine to the grid to sell the electricity?
The wind turbines producing less than 1kW of power are low-voltage machines, designed for charging 24v-48v battery banks. You will need a 'grid tie inverter' to feed electricity into the mains supply. These are special inverters that must meet the requirements set out in the G83 electrical standard (http://www.iee.org/Publish/WireRegs/Commentary-updateJun03.pdf )However, grid-tie inverters are usually designed for input voltages of 200-600v, so most are not suitable for this application. There are a few available for example Phillips can provide suitable equipment which accepts low voltage input.
How much maintenance do the systems require?
The wind turbines are very reliable. No strict maintenance is necessary, but the turbine blades should be checked regularly for damage, and to ensure that they are in balance, and the structural parts (tower, guy wires, anchors etc) should be checked for structural damage, cracks etc
Are spares available?
Yes, spares are available for these machines. The turbines are very reliable, so it is unlikely you will need spares, unless you make a mistake during installation.
Will the system need to be inspected by a electrician or be installed by an electrician?
As these are low voltage systems, you do not need to get an electrician to install or commission the system. However, if you plan to connect anything to your household wiring system, you should consult a qualified electrician.
What is the best way to utilise wind power?
Wind power is not a constant resource. For this reason there are three ways to use the wind:
1. Store the power in batteries, for reuse when needed
2. Use the power to provide heating (especially useful as houses lose heat faster in windy weather)
3. Sell the electricity directly to the grid, and buy it back when required.
Battery storage is the easiest way to utilise wind power. Our kits are supplied with charge controllers to regulate the power going to the batteries, but they are also supplied with a dump load, which will produce heat, once the batteries are fully charged.
What batteries should I use?
Any type of lead acid battery can be used, but the best batteries to use are 'deep cycle batteries'. Unlike car batteries, these are designed to withstand deep discharge without damage. They are made with much thicker and heavier lead plates, which are more resistant to damage, and last many times longer than conventional lead acid batteries. Deep cycle batteries are also used for forklifts and leisure batteries. We can supply suitable deep cycle batteries at excellent prices- please ask us for details.
Do not be tempted to buy gel cell batteries. These are good batteries, but not very suitable for renewable energy use. This is because gel cells are designed to be charged carefully, and within strict limitations. The variable nature of renewable energy makes this application quite unsuitable.
How many batteries do I need?
The smaller wind turbines are designed for 24v usage. The 500W turbine is designed for 36v and the 1kW for 48v. You therefore need to use the appropriate number of 12v deep cycle batteries connected in series i.e. 2x12v for 24v operation, 3x12v for 36v or 4x12v for 48v. If you need higher capacity, you can make up additional banks of batteries and put these in parallel - see diagram below:
What is the recommended system voltage and wattage, and why?
It is a matter of personal preference, and there are many variables that affect this decision. Often it is necessary to chose a wind turbine that has to integrate into an existing system - eg photovoltaics, an existing battery bank or a DC backup system. In this case, your choice of turbine will be determined to some extent by the existing system voltage. If you are not constrained by this, you need to work out how much power you require, and how much power is available. Wind power varies enormously from one site to another, and even at different locations on the same site, but as a general rule, in a good location you will expect about 30% of the maximum output when you average out over the whole year. You can expect proportionately more power during the winter months, and periods of bad weather.
Incidentally, it is possible to boost the performance of the wind turbine in very low wind conditions by using it will a smaller battery bank than intended. For example, if you use a 500W 36v turbine to charge 24v batteries, then the power curve will be shifted towards lower wind speeds, but with a penalty of having a lower maximum output. One customer reported that his Navitron 500W turbine massively exceeded the output of a Proven 2kW turbine in almost all conditions, when used with a 24v battery.
How do I connect the batteries?
The batteries should be connected in series to produce the required voltage. In other words, if you wish to make up a 36v battery bank using three 12v batteries, you should connect the negative terminal of battery '1' to the positive terminal of battery '2' and the negative terminal of battery '2' to the positive terminal of battery '3'. The charge controller output should then be connected to the positive terminal of battery '1' and the negative terminal of battery '3'.
Where can I get the cables for the batteries?
Battery cable can be made up from sufficiently thick copper cable, short lengths of steel or brass bar with battery clamps attached, or if you have screw terminals, you can make connectors from steel plate with appropriately drilled holes. It is also possible to purchase battery cable from battery or renewable energy suppliers, but expect to pay a high price!
Do you have 12v wind turbines for sale?
See below..... Also, from December 2005 we are now offering lower voltage options on the turbines.
Can I use the 200W/300W wind turbine with 12v (or 500W/1000W turbine on 24v)?
Yes, you can use any of the wind turbines that I sell on 24v or 12v systems. This will mean that the maximum power output is much reduced as the battery will act as a brake. For example, if you use the 500W (36v) turbine with 12 volt systems expect 1/3 of the power, so around 180Watts max, on a 24 volt system the same machine will produce about 365 Watts max. On the other hand your cut in speed is much reduced. If you were to use a 200 Watt (24v) Navitron wind turbine on a 12v system, its cut in speed will be reduced from around 4.5m/s to around 2.5m/s and on low wind sites, you will get much more power out of it over a week. You have to obtain a new voltage regulator to prevent over-charging of the battery.
How do I tell how charged my Batteries are?
The state-of-charge of a lead-acid battery can, to a certain extent, be estimated by measuring the open terminal voltage. Prior to measuring, the battery must have rested for 4-8 hours after charge or discharge and reside at room temperature. A cold battery would show slightly higher voltages and a hot battery would be lower. Plate additions of calcium and antimony will also vary the open terminal voltage. Furthermore, AGM has a higher voltage plateau than the flooded lead acid
| State of Charge | Voltage (open circuit) |
|---|
| 100% | 12.65v |
| 75% | 12.45v |
| 50% | 12.24v |
25% | 12.06v |
| 0% | 11.89v |
Why does my inverter shut down unexpectedly?
This can be for two possible reasons - either the inverter is overloaded, or the voltage is too low (due to battery voltage too low, poor battery connections or insufficiently heavy battery cable). The inverter shuts down before the batteries are completely discharged to protect the battery from damage
Should I balance the blades before use?
Yes. Balancing the blades will result in trouble free running, smoother operation with less vibration and longer bearing life.
How do I balance the blades?
This is actually quite simply. With the turbine in its normal position, and stationary, blades and hub attached, simply place a weight onto one of the blades extended horizontally from the hub. Start with the weight next to the hub, and gradually move it outwards until the blade starts to turn. Measure the minimum distance required to start turning. Repeat with each blade. If all the measurements are the same, then the blades are balanced. If however, one blade requires the weight to be further out, it means that this blade is lighter, and therefore more weight must be added. You can do this by sandwiching lead plates between the blades and the retaining plates.
WATER
What power output is available?
We can supply water turbines from 200W to 1000kW
What is the voltage/frequency output?
220v 50Hz single phase a.c.
Why not low voltage DC?
Because the higher voltage allows you to site the water turbine further away from the house without incurring heavy powerline losses. Also, it allows you to use these turbines directly with household wiring, without the expense and efficiency losses provided by an inverter system. It is of course necessary to ensure that the incoming mains electricity and the turbine-produced electric are kept separate using a changeover switch.
What about load variations?
All of our turbines come with an integral dump load connected to a voltage stabiliser circuit. Some manufacturers supply these at additional costs of hundreds of pounds. The voltage stabiliser ensures that a constant maximum load is placed on the turbine at all times. The circuitry reacts to changes in applied load, and feeds any excess power into the dump load, thus maintaining voltage and frequency.
What Head of Water do I need?
The minimum head is 1.8m. Ideally, you should have more head than this, as you need a large volume of water to produce sufficient power at low head sites
Can you survey my site for me, and tell me how much power I can produce?
Yes, we can, but it takes time, travel etc. We prefer to concentrate on offering the best products at the lowest prices, in order to make these technologies affordable. Consequently, we do not build-in the cost of so-called 'free surveys' into the price. Instead we try to offer all the information you will need in order to do it yourself. Therefore we can offer the service at a price, but you need to consider the cost of the survey with the cost of buying a turbine and some pipe to try it out. For small scale sites, our turbine prices are so competitive, you might as well do some crude calculations yourself, and purchase a turbine to test it out.
Can I survey my own site to save money?
Yes, of course! We encourage customers to do this, as surveying costs are high, and yet it is very easy to achieve fairly accurate results by carrying out a DIY survey. Many installers will try to make you believe that this is a magic art which requires great skill. Read below to find out how to survey your own water site, and then decide if you agree!
How do I calculate the potential power of a site?
You need to measure the maximum fall available and the flow rate. Bear in mind that flow rate varies considerably by season, and the turbine will not work if flow rate drops below the design requirements. The power output (watts) = head (metres) x flow (litres/second) x gravitational constant ('g' i.e. 9.81) x efficiency (~70%)
How do I measure head?
The best method is to use a laser level. Set up the laser level at the point where you intend to divert water from the main flow. It is easier to set this up at waist height, so measure the height difference from the level to the water level. Use the laser level to project a level to a point above the lower part of the water course, where you intend to place the water turbine (use a tall tree, wall or similar to project onto). Measure the difference in height between this projected level and the water level at the lower point. Deduct the height difference between the laser level and the water level at the top of the watercourse. This is your head. If necessary you can do this in several stages, if you are surveying a long watercourse. As a crude method, on high head sites, it is sometimes possible to use the height contours on an ordnance survey map to give an approximation.
How do I measure the flow rate?
This depends on the amount of water you are trying to measure. The flow of a small stream can be measured by finding a natural dam, or installing a crude temporary dam, and diverting the flow into a large bucket. Measure the capacity of the bucket beforehand, and time how long it takes to fill the bucket. For larger water courses, where this is impractical, you can estimate the average depth and width of the water. You can then drop a leaf or stick onto the surface of the water and time how long it takes to float 1m (or 10m etc). For example if the average depth is 1m and the average width is 5m, and it takes 4seconds for the stick to float 10m, then the flow rate is 5x1x(10/4)=12.5m3/second. To convert m3 into litres, simply multiply by 1000 i.e. 1000x12.5 = 12 500litres/second. If you have a river, you can often check the flow rate simply by telephoning the Environment Agency, who monitor the flow of most rivers. Some of the information is even available online.
I have not got enough head. Perhaps I could use a small nozzle to get extra pressure and therefore more power?
Power is dependant on flow rate and head. Nothing else...or at least, nothing you can change (the gravitational constant and the density of water).
HEATPUMPS
Are the Heat pumps suitable for single phase or 3 phase electricity?
The 5kW and 9kW heat pumps are suitable for standard 240v single phase input.
Can you provide larger heat pumps?
Yes, we can provide heat pumps up to 16kW. Larger units are available on request
How does a heat pump work?
A heat pump does not create heat, but rather it moves heat from one place to another. Your refrigerator is a heat pump that moves warm air from inside the box to outside making inside the box colder. A ground source heat pump collects heat energy stored in the earth and transfers it inside your home. However, it does so very efficiently - up to 6 times as much heat is produced compared with the electricity required to run it.
I’ve heard heat pumps don’t work very well in cold climates.
Some air source heat pumps, especially the older models, don’t perform well when the outdoor temperature drops below freezing. Ground source heat pumps connect with the earth and are not affected by freezing temperatures.
How is the heat transferred between the earth and my home?
The earth has the ability to absorb and store heat energy. To use that stored energy, heat is extracted from the earth through a liquid medium (groundwater or an anti-freeze solution), and is pumped to the heat exchanger of the heat pump. There it’s converted into usable heat for the home.
Horizontal Loop System
How much can I save?
A ground source heat pump is three to four times more efficient than a conventional furnace. The unit is moving heat- not creating it, so the only electricity being used is to run the compressor and fans. It will cost less to operate than a high efficiency natural gas furnace or wood stove, and much less than a propane or electric furnace.
Can I use the Ground Source Heat Pump to Cool my house in the summer?
Yes, you can select the cooling function on the control panel to run the system in reverse and provide cooling in the summer.
How does the cooling work?
In the cooling mode, a ground source heat pump takes heat from indoors and transfers it to the cooler earth. You can change from heating to cooling with a flick of a switch on the indoor thermostat.
How does it connect with the earth?
The actual connection is made either through groundwater - an open loop system like a well, or an underground, closed loop system. Most installations use a closed loop.The closed loop uses a continuous loop of a plastic pipe, buried to make contact with the ground.
What can I use for the ground source loop?
There are a variety of heat sources you can use:
A loop or several loops of plastic pipe buried in the ground, at a depth of at least 2m
Well water/stream water/river water/sea water pumped directly through the heat pump, using a suitable filter to prevent ingress of dirt and abrasive particles.
Water pumped directly from a bore hole, and returned to another bore hole at least 10metres away
Where is the buried loop located?
That depends on land availability and terrain. Most closed loops are trenched horizontally in yards adjacent to the house.
How deep and long are the trenches?
Trenches are normally 1 to 3metres deep. Plastic pipe is placed in the trench, often in multiple layers. Trench length will depend on size and insulation levels of the house. Alternatively, the pipe can be laid out as 'slinkies' which reduces the required trench length.
What length of pipe will I need for the ground loop?
Typically for the 9kW unit, you will need approximately 300m of pipe. Standard PVC pipe 20mm diameter is sufficient. This can be purchased as 150m rolls. Typically in warmer climates you should lay 1m of pipe per 40watts of heatpump (heating) rating. In colder climates, 1m of pipe should be laid for each 30watts of heatpump. The pipe should be laid between 2 and 4metres deep. If space is limited, it is possible to lay pipes at different depths in the same trench - eg 4m/3m/2m.
Should I use antifreeze in the groundloop?
Yes, ideally. In case of leakage, it is important to use a non-toxic antifreeze. The cheapest and easiest solution is to use common salt. You should add enough salt to protect to -12C.
Do I need separate ground loops for heating and cooling?
No. The same loop works for both. The only thing that happens when changing from heating to cooling, or vice-versa, is the flow of heat is reversed.
What if there’s no room for a horizontal loop?
Closed loop systems can also be vertical. Holes are bored to about 40 to 60metres. U-shaped loops of pipe are inserted into the holes, and the holes are backfilled with sealing solution.
Vertical Loop System
What is the pipe made of?
Closed loop systems should only be installed using high-density polyethylene or polybutylene plastic. These pipes are inert to chemicals normally found in the soil, and are guaranteed for 50 years. PVC pipe should not be used under any circumstances.
Can I put a loop in a pond or a lake?
Yes, if it’s deep enough and large enough. A minimum of six feet in depth at is lowest level during the year is needed for a pond to be considered. Certain permits may be required to place a loop in a lake.
Can a ground source heat pump also heat water for hot water?
Yes, by using a device called a desuperheater. Desuperheaters are standard on some units, and optional on others. Producing high temperature water can be very inefficient with heat pumps by comparison to the standard COP rating. The WRB series heatpumps do not have a desuperheater facility.
What size water pump should I fit to circulate the ground-loop water?
The circulation pump for the ground loop is not included in the heat pump (however, an internal pump is provided to circulate the heated output water). We recommend that the pump should produce a flow rate of at least 0.25litres/second and be capable of working with a 10m head. Bearing in mind the resistance of the ground loop, this generally requires a circulation pump of at least 250watts electrical consumption.
How does a photovoltaic cell work?
The term Photovoltaic is derived from the Greek word for light 'photos' and 'volt' which is the term for electromotive force. PV cells convert solar energy from the sun into electricity through semi-conductor cells.
A PV cell is made up of two thin layers of dissimilar semiconducting materials, usually made from silicon which have been treated with small amounts of substances giving the cell the means to produce electricity.
The cell is made from two layers. The first layer is called the P type layer and is created by treating the silicon with tiny amounts of the element boron- this causes a shortage of electrons and hence a positive charge. The second layer is called the n type layer, this is treated with phosphorous creating a surplus of electrons and hence a negative charge.
The 'barrier' between these layers is called the p -n junction. When light energy is applied at this junction the electrons are given enough energy to move across the junction. In turn this generates an energy difference, otherwise known as a potential difference or voltage. If a circuit is made this drives the flow of electrons around the circuit producing an electrical current.
