By late September 2009 the KWB Wood Pellet "Easyfire" boiler was up and running. The next obvious step was to install Solar Panels. Our boiler installer did quote us for Solar Thermal ('ST' for hot water) but he didn't have MCS Accreditation for the Photovoltaics. We figured we would have both for one simple reason - we had lots of roof space. The house had been chosen for its large south-facing roof. In our last post-carbon home we easily installed a 1.5kWp Photovoltaic system and that roof was significantly smaller. It remained to be seen how much we could shoe-horn onto the new roof but double seemed to be a reasonable starting point. Afterall the ST is limited in size. Once you have enough to provide all your hot water needs in summer then you can't install a bigger system. However, with Photovoltaics ('PV') you can install as much as you like and export any excess to the Grid and get paid for it.

So we decided to go for an installer who could do both PV and ST. We figured this would be the cheapest option and indeed it certainly should be. Think about it - if you are going to put up scaffolding you only want to do it once - hence pay for it once. You could call it economies of scale. You certainly need to put up as much PV as you can afford and have roof space for. The reason is that the Installer's costs are largely fixed. The incremental cost of each kWp of panels is small in comparison to their labour charge. For example, a 1.5kWp system might cost you about £9000 but £7000 is fixed cost whilst the incremental cost of the PV is about £2000 per kW. Hence ordering a 2kWp system doesn't cost £18000, it costs only £11000! Of course this is still a lot of money. But you get it all back.... Read on.

So in December 2009 we decided to get cracking with some quotes. We knew that we needed planning permission as we live in a Conservation Area. Hence we needed some illustrations of the proposed installation. The Planning Permission would take a couple of months judging by our experience with the Biomass Boiler Flue. As we wanted to get the installation done in April 2010 we figured that starting the Planning Permission process in late December was the best option to give us time to choose an installer. There were a couple of other important factors concerning timing too. Firstly the Feed-In Tariffs (more about them later) started in April 2010. Secondly we wanted to qualify for a Low Carbon Building program grant. In our case the latter would be £1000 as we had already had £1500 for the Biomass Boiler and the LCBP grants are capped at £2500 per household.

As it turned out our timing was perfect. We put in the application for the grant and was awarded it only a couple of months before the PV grants were scrapped. Thankfully it didn't effect existing grant commitments. Getting both the FIT and the LCBP grant is a matter of timing. That window of opportunity has now passed but a similar window is open between April 2010 and February 2011 for a grant for your ST before these too are scrapped in favour of the April 2011 introduction of the Renewable Heat Incentive (more about that later too). You qualify for FIT and RHI even if you had a LCBP grant.

We downloaded the list of MCS accredited installers from the LCBP website and browsed it for local installers. We chose one from Oxford, one from Aylesbury (Buckinghamshire, UK) and one from Slough. All three came over and gave us quotes. There was a little bit of uncertainty about whether both an ST and a 3kWp PV system could be shoe-horned on the roof but we set the bar high for the installers and they all quoted for the requested capacity. There was then a pause during January and February as we awaited the Planning Permission. In this time another installer came on the scene who had been introduced by a local Transition Town. This installer was not local (being based in the west country) and they were the only installer who refused to quote for the full 3kWp PV system. This installer and the one in Oxford also proved to be the most expensive so we finally ruled them out. They were over-charging us for something we didn't want. It made no sense. That left us with two vendors.

The end of February came and went without us hearing any more from the local Planning Department. We lost patience and E:Mailed them. This provoked a swift reply and the Planning Permission was granted in full the next day. This brought us into March. We then entered a brief period of fierce haggling with one of the installers who refused to be beaten on price. This had not been the original intended approach but we got the price down quite a lot. It was an enlightening experience that we will take forward when we implement a renewable energy club with our local Transition Town. It seemed to us that this is much like buying a car. There is no shame in haggling and playing one vendor off against another. It also proved to us that not all installers are the same as they all offer different technologies from different manufacturers. You should always consider a variety of options which may lead you to not choosing the cheapest system. Instead you should end up with the best value system - an important consideration as it is strapped to your roof for 30 years and will generate you income. Can you say the same about a car or a fitted kitchen?

Having chosen our installer we quickly paid the deposit and had a promise from them that they would install in the first week of April. This was important because the end date of the LCBP grant was 15th April and we knew that meant that the LCBP administrators needed all the paperwork BEFORE that date. So we waited and waited. Easter came and went with no installers turning up. I dropped an E:Mail to the installer reminding them of my deadline and their promise. All of a sudden everything started to happen. They phoned right back promising me that the install would start the very next day (Wednesday 7th April 2010). Indeed it did.... Read on.

Pictured above - the Inverter in the attic.

Pictured above - the scaffolding up around the house.

Pictured above - the first PV mounting rail in position.

Pictured above - a view underneath the PV panels from the garden.

On the 7th April 2010 the electricians turned up before the scaffolders did. However there was plenty for them to do as they started in the attic. The Inverter goes there. This takes the DC (direct current) from the PV panels and converts it into AC (alternating current) before feeding it into the house fuse box ("consumer unit"). Our consumer unit was ancient so we had a local electrician come in a couple of weeks before and replace it for us. IEE regulated electricians will do a very thorough and safe job. We had all the electrics in the house checked and given a clean bill of health.

There was a good morning's work to be done with the internal wiring. A very neat job of Inverter installation was done. We asked that it be put at a height that would allow us to store items beneath it in the attic space. The electricians did exactly as we requested. They even supplied a lovely piece of wood which they fixed to the roof rafters, at one end of the attic, to mount the Inverter on. When we asked it turned out to be a section of the installer's daughter's old wardrobe door. Lovely! In our last post-carbon home the Inverter had been put at knee level in an inaccessible pat of the attic. So this was all a big improvement. Next the electricians moved into the Garage where the consumer unit was. There they fitted the Generation Meter and an isolator switch so that the PV power could be switched off by anyone working on the Meters or the Fuse Box.

Next the scaffolders finally turned up. After much cajoling, tea and biscuits they were finally persuaded to actually do something. The scaffolding was then erected quite quickly. It was meant to curl around the side of the neighbour's house too. We had not been warned about this in advance and the neighbour's were not in to be asked. The scaffolders refused to do it without the neighbours permission so left the site with the job half done - but with a promise they would come back the next day to finish the job. We never saw them again. Despite a quick chat with the neighbour's to secure their permission (it was a courtesy really) we later found out that the scaffolders had claimed they were not being paid enough to do the full job. As it turned out the extra scaffolding was really for safety purposes. There was enough room to get all the panels on without it - so the installers soldiered on.

As soon as the scaffolders were finished the PV installers crawled all over the roof fitting brackets to mount the PV upon. These are "U" shaped and one half slides under your roof tiles to be bolted to the roof rafters underneath. This is actually very time consuming and it was to take two days to get all this done. When it is done then a set of aluminum extruded rails were bolted to the brackets. On top of these are bolted the photovoltaic panels.

That Wednesday afternoon the plumber arrived to work on the Solar Thermal. More about his work later. He quickly assembled a frame for the solar collectors and tried it out on the roof space. As it turned out it was a perfect fit. Previous concerns about not getting all the PV on the roof were dispelled. The two systems fitted perfectly side by side fully endorsing our gut-feel for what would fit.

The electricians ran armoured external mains cable from the Inverter in the Attic, out through the gap between roof and walls, down behind a drain pipe ad then into the garage via a carefully drilled hole. From there it was run along a pipe and then down to the Consumer Board. The Inverter is connected to the household mains electricity supply for reference. It then makes the voltage and AC frequency of the PV output the same as that coming into the house from outside. If there is a power cut the PV is isolated from your mains supply for safety reasons.

In the end we got exactly what we wanted. Sixteen 185Wp Mitsubishi ("PV-TD185MF5") Photovoltaic panels giving us a total of 2.96kWp. The system should yield 2516kWk/year based upon a BRE estimate of 850kWh/kWp/yr on a south facing roof in the south of England. Each kWh offsets 0.568 kgCO2 per annum making us a total of 1.68 tonnes CO2 save per year. It took three days to install without difficulty. The job would have been wrapped up by 3pm Friday afternoon but two electricians spent two hours in the attic doing something. When we asked they admitted that something wasn't working. However they replaced a section of wiring and everything was now working correctly. They ran through the commissioning paperwork and were gone by 5 o'clock. Great job lads!

Pictured above - the household consumer unit in the garage with PV Generation Meter and isolator switch.

Pictured above - the roof mounting brackets for the PV system.

Pictured above - the PV panels mounted on the rails.

Pictured above - the frame for the Solar Thermal tubes.

Pictured above - the bottom of the ST frame showing the lower caps that support the tubes.

Pictured above - the old DHWC prior to removal.

Pictured above - the Airing Cupboard after the old DHWC was removed.

Pictured above - our installer fixing in the last of the Solar Collector Tubes.

Pictured above - a close-up of the bottom of the collector tubes.

Pictured above - the Solar Thermal Tubes in position as seen from the ground.

The Solar Thermal ("ST" or "Solar Hot Water") installer turned up a bit later on the first Wednesday. Unfortunately the Gledhill twin-coil hot water cylinder wasn't ready yet but the installer was able to fit everything else. He soon had the tube frame mounted on the roof. These are mounted differently from the PV system as they are smaller, lighter and fitted closer to the roof surface. The PV system is heavier and mounted a couple of inches off the surface so that cooling air can flow underneath. PV works better when cool whilst ST likes to get really hot (of course). Hence small holes are drilled directly through the roof tiles and then long screws are screwed directly into the roof rafters. Rubber washes protect the tiles from breakage.

Next came the internal work. A pumping station is mounted on the attic wall on the opposite side to the PV Inverter. This all worked out quite well as electricity and water don't really mix very well! Thankfully the layout of the house meant that the garage and consumer board are at the western end whilst the hot water tank is at the eastern end of the roof space. There was no vying for limited space - there was plenty. An expansion tank is mounted on one rafter. Flexible tubing is laid out between pump and roof. More tubes go from pump station down under the loft insulation through to the airing cupboard.

Due to the delay with the Gledhill tank we had to wait another week before the installer could come back to finish the job. In that week the tubes themselves couldn't be put in place so the scaffolding had to remain in place.

Finally the tank turned up after some comic comings and goings. It had been delivered to the installer's head office in Slough rather than our home. Gledhill had turned up at our home expecting to collect a cylinder they had never delivered. Apparently the original cylinder wasn't correct. It didn't have a sensor pocket for the DHWC temperature sensor for the KWB Easyfire. The survey should have picked this up but the surveyor was an electrician not a plumber. He had no interest in the ST system's requirements and only took a photo of the Hot Water Cylinder. It really pays to have a proper survey done by your installer. By 'proper' we mean thorough! It didn't result in much inconvenience for us really as the time restriction was on the LCBP Grant. Since that as related only to the PV installation then we were perfectly happy to accept a small delay.

The installing company were very good in bending over backwards to get us all of the right paperwork so we could complete the grant application. However we think the old adage is true - "more haste, less speed"!

After the right tank turned up we soon found our old domestic hot water cylinder sitting on the front lawn. The swap over was completed in under a day so there was no inconvenience of having no hot water or heating. The water is off for a few hours obviously but it was of no great inconvenience. You fill up your bath with water and flush the toilet with a bucket! If you have a bit of "Blitz spirit" then this is just part of the fun.

The old hot water cylinder was in a poor state. It was only fitted by the previous home owners back in 2003. It was heavy with lime scale as this is a hard water area and they had no water softener fitted. We had our water softener fitted after the KWB went in so this damage is now unlikely. The new cylinder has a 170 litre capacity. The old one had only a 100 litre capacity. The lime scale probably accounted for a lot of that so we easily doubled our hot water capacity. This now stops us from running out of hot water after a couple of showers. A really big help around the home!

The only downside was the loss of space in the airing cupboard. The new cylinder was taller and thinner. It mean we lost half a shelf. Later on we managed to reconstruct a partial-shelf from bits of left-over shelves to give us a bit more storage space there. Due to the limited width of the tank there is more space in front of it. You can stack quite a few shoe boxes there. So we will probably find some small shelving units that will fit well.

The only significant set back during the install was the flood of water after the new tank was connected. This lead to an embarrassing near-panic by the installer who feared he had not connected something properly. We quickly ran around the house and put down some blankets, plastic sheet and buckets to catch the drips downstairs. Thankfully no damage was done.

The problem was quickly located to the hole at the top of the cylinder where the Domestic Hot Water Cylinder normally slots. The installer had decided to use the immersion heater electrical spur for the Pump Station so he elected to specify a tank with no immersion heating element. All well and good but Gledhill didn't supply the cap to go over the hole. This would have been quickly rectified if they had not covered the hole up with a plastic over-wrap that had been taped in place permanently. Once ripped off the problem was obvious. The installer popped out to buy a tank cap and all was then well. However, red-faces all round and an eternally apologetic installer resulted.

Despite this we felt it was Gledhill's fault and didn't blame the installer who, otherwise, did a superb job. It was just unfortunate. We were lucky that no damage resulted as the problem was spotted quickly and the water switched off before too much over-flowed.

This incident did waste a bit of time but the installer made up for it and everything then slotted neatly into place. Soon it was back to the roof to put in the evacuated tube solar collectors. These do not actually have any fluids flowing through them that are connected to the hot water cylinder. The heat transfer glycol fluid, that takes the heat down to the hot water cylinder, only flows through the top part of the ST frame. It extracts the heat from the very top of the tube. Inside the tube is a long thin element which absorbs the heat and conducts it to the end of the tube. This makes the entire assembly easy to install. It is easy to add or remove the tubes. We were even supplied with a spare!

Before the installer left he showed us how to operate the system control panel that is mounted in the airing cupboard. This delightful box of tricks gives a clear visual read out of tank temperature. You can set the desired temperature to whatever you wish. There is also a "holiday mode" which you can use to prevent the system over-heating if you are not using the hot water for several weeks. It all gave us a great feeling of having a system we were fully in control of.

Our system is a 20 tube ETZ2580 BE Solar System. The tubes are 1.8m long giving a 1.87m² aperture.

By the late summer the glycol in the system had vanished and we had to get BritishEco back to refill and recommission the system. Various theories were forwarded on why this happened and we still await a follow-up visit in 2011 to perform other minor rectifications. We suspect that the roof sensor doesn't read correctly but the installer disagrees. They wish to fit a valve to stop reverse siphoning.

Pictured above - the Solar Pump Station in the attic

Pictured above - the piping from Pump Station to Solar Collectors

Pictured above - the top-right-hand side of the ST frame showing the pipe mounting.

Pictured above - the left hand-side of the ST frame sowing how close it is to the PV panels (left)

Pictured above - the old cylinder and the new.

Pictured above - the new cylinder in the Airing Cupboard.

Pictured above - the Tubes being secured.

Pictured above - the airing cupboard after all the pipes were re-insulated and the shelves replaced.

Pictured above - the finished Inverter installation in the attic showing generation of 2100W.

Pictured above - the finished installation minus scaffolding.

Pictured above - a clear view after the rear garden trees were removed - June 2010.

This is not the first Solar Panel system we have had installed. It is the first Solar Thermal system we have had installed and the combined system represented a much larger capital investment than before. Overall we are very happy with the price we paid and the installation.

However there were a few things that could have gone better. The issue with the over-flowing tank we felt was just bad luck and relatively trivial so we won't mention it again. The other things were:

• Inadequate technical survey for the ST leading to incorrect tank being specified

• The fitted tank didn't have an electrical Immersion heater although it was meant to be a like-for-like swap. Installer didn't want to run a new electrical spur to power the Pump Station

• Installer didn't copy the Quote to the Sales Order. They copied it from another order so it had copy and paste errors

• The order & job sheet omitted the remote energy display monitor that was on the quote. They had to come back and retrofit this twenty days later.

• All paperwork had the wrong address on.

• There was no explanation as to why the tank was not ready for the installation as the deposit had been paid five weeks before

These 'niggles' to one side we had a good relationship with the installer. They dealt with all the problems swiftly and professionally. They are a large national operator and all their installers are contractors pulled in from all over the place. The surveyor came from Watford (only about 30 miles away) and he was meant to be the original installer of the PV. In the end they pulled in guys from Rugby for the PV and then from Sussex for the ST. So they were not quite as "local" as we may have wished but all were highly competent and all did a very good job. We suspect that given the tight deadlines the installer had to use whoever was free. The contractors are probably normally chosen for the locality to the install. We were probably the exception.

Both the PV and ST systems are working fine. After 17 days of operation in April the PV had generated 214 units of electricity. They are on target to generate over 330 per month through Autumn, Spring & Summer. Not bad considering that we consume only about 260 units per month.

The handover of the ST probably could have been slightly improved. We were left to drain the air from the system. This is an easy job but it takes several days to complete and involves a daily trip up to the attic. I am sure many customers, and specifically the elderly, may well object to this initial chore. We also received no advice on the day about how to get the best from the system. Since the hot water cylinder is joined to the same system as your regular boiler then there is nothing to stop the boiler supplying all the heat and the ST system doing nothing.

So we applied common sense and did the following:

• Set the Boiler DHWC Temperature to 55 to 58^oC

• Set the ST DHWC Temperature to 60 to 65^oC

• Change your Boiler times so that it acts as a top up only after the hours of daylight are over

Some experimentation may be required to get the best out of the combined boiler/ST system. You want the sun to do most of the work but you also need the boiler to kick in when the sun is not available! It might require a delicate balance. We spoke on the phone to the installer some days later and he agreed that the action we had taken was perfectly correct.

In our case the change from the 100 litre tank to the 170 litre tank makes a big difference because it can store 24 hours worth of hot water. We were originally offered a 270 litre tank but we did some maths about our actual hot water usage. We measured up the sink and bath to estimate their capacity. We also measured the output of the shower by cutting the top off a 2 litre plastic milk container then ran the shower into the container and counted how many seconds it took to fill. This will give you the flow rate in litres/minute. Multiply this out by the length of your showers.

We finally concluded that the typical day needed between 110 and 150 litres of hot water. 270 litres would have been too much and would have consumed all our storage space in the airing cupboard. It allowed us to save a bit of money and have a slightly smaller ST system on the roof.

Your installer will estimate your usage based upon a rule-of-thumb. This may be based solely upon the number of bedrooms in the house. This is what the Water Companies do and it isn't accurate as it doesn't allow for how many people are in the house nor for their patterns of water usage. Hence estimate it yourself and it will guarantee you get the right system at the right price.

Our conclusion? Get Solar Panels. Read up on the FIT & RHI (below) and you will see how it makes economic sense now more than ever.

Pictured above - the PV panels in foreground with the Biomass Boiler Flue in the background.

Pictured above - view from the ground.

Pictured above - in the lounge on the wall. Three boxes. The middle one shows the output of the Photovoltaics.

• Not as good as they used to be!

• The RHI & FITs were a great idea.