Installing Photovoltaic Panels in Scotland in 2010
In January 2010 we decided to look at installing Photovoltaic (PV) or electricity generating panels on our roof. The average UK household's electricity use is about 3500kWh (kilowatt hours) per year. A kilowatt hour (kWh) is the amount of energy used to run 10 old 100 watt light bulbs for an hour.
To produce this amount of electricity in central Scotland on a South South West facing roof at 40 degrees from the horizontal we needed a 4kWp (kilowattpeak) system.
In the UK from April 2010 the electricity companies are required to pay customers a certain amount for every kWh of energy they produce. In 2010, for systems under 4kWp this is 41.9 pence per kWh generated. They also have to pay 3p per kWh put back into the grid. We also need to remember that all the energy used in the house doesn't need to be paid for giving a saving of about 10 pence per kWh.
In Spring 2010 this size of system would have cost about £15,000 on a bungalow with easy roof access.
In April 2010 we won the Future Friendly Family Award (see our page on this under Home) giving us a £10,000 bursary which we added to our already planned system. This resulted in a 7kWp system expected to produce 5500 kWh per year. We are higher than average electricity users as we have an airsource heat pump. The feed in or pay back for this size of system is 36.5p per kWh. The logic being a system is cheaper per kWh the bigger that system is.
Planning permission in Scotland in 2010 is not required so long as the system complies with the Town and Planning order Article 2(2) Part 1A Class 6A. Confirm this with your installer. Not all planning departments know this.
A building warrant is needed to ensure that the house roof can cope with the additional weight. This is straight forward to do. There is a cost which is proportional to the cost of the project. Ours was £460.
With a system above 4kWp you need "G59" approval from the owner of the electricity network ( The electricity company who owns the cables running to your house). In our case Scottish Power. This is to ensure we don't blow the system as electricity cables were designed to bring electricity to our houses not take it away. Unfortunately in the case of Scottish Power it took several weeks to find out how to make the application, only to find it would take a minimum of 3 months to get the assessment of the network done. So if you are having a system above 4kWp put in, start this process early. I am told, other suppliers are significantly quicker than this - 24 hours to one week.
If your system is below 4kWp (producing about 3200kWh per year), which most will be, then you need a "G83" completed. This is done by your installer once the system is installed, so the electricity network owner knows you are an electricity producer. This shouldn't incur delays.
September 2010 - the 28th we finally got the OK by to go ahead with the installation. Scottich Power's charge £734.66.
Then in October:
To produce this amount of electricity in central Scotland on a South South West facing roof at 40 degrees from the horizontal we needed a 4kWp (kilowattpeak) system.
In the UK from April 2010 the electricity companies are required to pay customers a certain amount for every kWh of energy they produce. In 2010, for systems under 4kWp this is 41.9 pence per kWh generated. They also have to pay 3p per kWh put back into the grid. We also need to remember that all the energy used in the house doesn't need to be paid for giving a saving of about 10 pence per kWh.
In Spring 2010 this size of system would have cost about £15,000 on a bungalow with easy roof access.
In April 2010 we won the Future Friendly Family Award (see our page on this under Home) giving us a £10,000 bursary which we added to our already planned system. This resulted in a 7kWp system expected to produce 5500 kWh per year. We are higher than average electricity users as we have an airsource heat pump. The feed in or pay back for this size of system is 36.5p per kWh. The logic being a system is cheaper per kWh the bigger that system is.
Planning permission in Scotland in 2010 is not required so long as the system complies with the Town and Planning order Article 2(2) Part 1A Class 6A. Confirm this with your installer. Not all planning departments know this.
A building warrant is needed to ensure that the house roof can cope with the additional weight. This is straight forward to do. There is a cost which is proportional to the cost of the project. Ours was £460.
With a system above 4kWp you need "G59" approval from the owner of the electricity network ( The electricity company who owns the cables running to your house). In our case Scottish Power. This is to ensure we don't blow the system as electricity cables were designed to bring electricity to our houses not take it away. Unfortunately in the case of Scottish Power it took several weeks to find out how to make the application, only to find it would take a minimum of 3 months to get the assessment of the network done. So if you are having a system above 4kWp put in, start this process early. I am told, other suppliers are significantly quicker than this - 24 hours to one week.
If your system is below 4kWp (producing about 3200kWh per year), which most will be, then you need a "G83" completed. This is done by your installer once the system is installed, so the electricity network owner knows you are an electricity producer. This shouldn't incur delays.
September 2010 - the 28th we finally got the OK by to go ahead with the installation. Scottich Power's charge £734.66.
Then in October:
25th October 2010
On time, as planned the installers arrived and started work on the roof. It was a frosty but clear morning. The holders for the frames for the PV panels need to be fixed through the water proof membrane and sarking to the roof trusses. We have thick roof trusses that are regularly spaced, so once the first was found the rest were locatable and by the end of day one most of the holders on one roof aspect were in place
26th October 2010
Again on time the guys arrived, this time in rain as well as cold. However, they plugged on all day and got the holders on the other aspect of the roof, fixing a few loose tiles as they went. The tiles where the holders attach to the roof are a little raised, this will be sorted as the frames are added. Though as they stand, due to the roof tile overlap, they are wind and water tight. They left about 3pm to fill the van for tomorrow with the panels, inverters and G59 switch.
27th October 2010
Again, the guys arrived on time and today we have solar panels on our roof. After all the background it seemed to happen very quickly. The panels fit on to the rails and are screwed on. The wireing is fed behind the panels to a single entry point on the roof, behind the panels.
Once the panels were on the South East facing roof they got on with the rails on the South West facing roof. As you can see they got most of the supporting rails on.
And they put in the inverters and the G59 switch. The red boxes are the Sunny Boy inverters. You can see the wiring from the South East facing panels coming in to the two grey switches on the right. Though they aren't wired in to the inverter as yet. The grey box to the very left is the G59 switich.
An amazing days work
An amazing days work
28th October 2010
The panels on the South Westerly roof face are now all in place and the wiring into the switches is done.
29th October 2010
No photos as it didn't look much different. The wiring from the panels to the inverters was finished, then from the inverters to the G59 switch and then finally the electrician connected the whole system up to the mains. We were allowed to test it to make sure it worked and we generated 4kW of electricity. Now we have to switch it all off for a week until the Scottish Power engineer comes out to check the work.
G59 testing
If you look at the picture of switches from 27th OCtober, the PV panels feed into the solar inverters (red boxes) and then in to the G59 switch - grey box. Scottish Power insist on checking the G59 switch to make sure it will cut off the PV panels in the event of the electricity beeing cut off - to prevent theire engineers being electrocuted - and if the frequency or voltage of the electricity from the inverters varies.
To do this a specialist bit of equipment is needed. Unfortunately, Scottish Power do not travel with one, and nor does our installer. Scottich Power didn't think to discuss this with our installer despite checking that he would make sure the system was working.
It turns out that the Scottish Power engineer, though having done many G59 switch checks on commercial projects has never done one on a relatively small domestic project.
Sadly, the first set of testing equipment sent for trial on the 16th November was faulty so a further set needed to be collected. However, the second set sent for 19th November worked, and the equipemnt passed it's test so we went live about 3.20 pm on 19th November.
If you are going over the 4kWp and need a G59 switch check about the testing equipment. The result for us is that the switch on has been delayed till the 16th November and the cost of hiring the testing equipment will be £500.
To do this a specialist bit of equipment is needed. Unfortunately, Scottish Power do not travel with one, and nor does our installer. Scottich Power didn't think to discuss this with our installer despite checking that he would make sure the system was working.
It turns out that the Scottish Power engineer, though having done many G59 switch checks on commercial projects has never done one on a relatively small domestic project.
Sadly, the first set of testing equipment sent for trial on the 16th November was faulty so a further set needed to be collected. However, the second set sent for 19th November worked, and the equipemnt passed it's test so we went live about 3.20 pm on 19th November.
If you are going over the 4kWp and need a G59 switch check about the testing equipment. The result for us is that the switch on has been delayed till the 16th November and the cost of hiring the testing equipment will be £500.
