Thursday 31 May 2012

How to Submit FiT Readings to British Gas to Get Feed In Payments?

How to Record British Gas FIT readings


When we had our Solar Panels installed we investigated the different options for registering our PV Panels under the MCS Scheme for the Feed In Tariff payments (FIT). We found there was no need to register your FITs with the electricity company that supply your energy. As our panels were installed very close to the December 2011 FIT payment being cut we wanted to make sure that our installation was registered in time so chose a FIT payment supplier that accepted applications online and also had a good record of paying FITs on time. There were many horror stories of EDF taking months to pay out but our experience with British Gas has been very positive so far.

How to Submit FiT Readings to British Gas to Get Feed In Payments?

We have recorded two FIT readings with British Gas now and are currently waiting for the second payment to arrive having submitted the readings recorded on 21 May.

To submit FIT readings to British Gas you need to send them as an email. The email must contain the following items:

Your Name
Your Address
Your Reading
The date of the reading

We use the British Gas reference number as the subject line of the email and the email is sent to  feedintariff@britishgas.co.uk 

More info on the British Gas FIT scheme here

http://www.britishgas.co.uk/products-and-services/solar-panels/solar-pv/feed-in-tariffs.html


How to Record British Gas FIT readings
How to Record British Gas FIT readings

Can I Use an iPhone to Communicate with My SMA Sunny Boy Inverter via Bluetooth?

When our solar panels were first installed I tried to connect to the SMA SunnyBoy inverter using my iPhone as it has Bluetooth already setup. The iPhone was unable to detect the SMA Inverter so initially I thought the Bluetooth was not configured on the SunnyBoy. However on further investigation it was possible to connect using a laptop so it appeared the problem was with the iPhone Bluetooth settings.

It seems like the iPhone Bluetooth configuration is very much restricted and that features that are standard on other Bluetooth devices are not possible on the iPhone hence the inability to communicate with the SMA inverter.

So the answer to the question "Can I Use an iPhone to Communicate with My SMA Sunny Boy Inverter via Bluetooth?" is unfortunately No.

Wednesday 30 May 2012

Why is The Peak Output of Solar Panels So Low? Why do my solar panels generate less than their rating?

When we got our Solar Panels I expected that they would generate electricity at a constant rate and that would be the same whenever the sun was shining. The reality is rather different. The output of your solar panels is affected by the length of the day, the temperature, the height of the sun in the sky and the cloud cover.

If you are finding your solar panels have a low Peak Output, much lower than the nominal kWp output that they are rated at then the most likely cause is temperature. PV Solar panels are less efficient the hotter they get and their rated output is measured at 25C. It is very noticeable that on a cloudy day the output can peak at very high levels, close to the maximum rating of the panels.

For some mixed sunny/cloudy days in April we got 3kW peak output from our 3kWp solar panels when the sun came out from behind a cloud. For consistently sunny days during May the daily peak has been far lower at around 2.3kW.


Why is Solar panel low peak output on hot days
Solar panel low peak output on hot days

You can see the difference in the graph above from April with the peak on the cloudy then sunny day reaching 3kW but the completely sunny day warmed the solar panels so the peak was lower at only 2.5kW. In May the peak electricity output was even lower due to the heat at 2.3kW.

Monday 28 May 2012

Effect of Temperature on PV Solar panel output in the UK

What is the effect of Temperature on PV Solar panel output in the UK?

How much variation does temperature cause for generating electricity from Solar PV Panels?

With one of the hottest days in the UK so far this year it is interesting to compare the output for a hot sunny day with a cooler sunny day earlier in the year.

The best generating day in April was 19kWh for a clear sunny day with temperature of 12C. Yesterday generated 17kWh for a clear sunny day with a temperature of 27C despite the longer generating time with the lengthening days.

Graph showing Effect of Temperature on PV Solar panel output
Solar panel output with different temperatures.
As you can see the output was for longer on the blue day (24 May) but the peak was lower than on the green day (2 April) as the temperature was far lower. The equation is the temperature coefficient which for our panels is 0.5% meaning output drops by 0.5% per degree over 25C. So for panels at 35C which is 10 degrees higher the output would be 5% lower.

As another comparison the maximum peak generation was around 2.3kW yesterday but for cooler days this has been as high as 2.5kW and for cloudy days with sunny spells it has peaked as high as 3kW showing the effect that temperature has on solar power generation.

One company was selling a hybrid solar panel that included water heating as well as electricity generation. As a method for cooling the solar panels to improve their efficiency it seems like an effective method based on this data as the water will extract the heat that can then be used for hot water in the house.

Solar panel generation in high temperatures

Friday 25 May 2012

Best Solar Output So Far - Today Breaks 20kWh Barrier

With a reasonable breeze today and slightly lower temperatures we have broken the 20kWh for the first time and got a new record for the electricity generated. By the time the sun set today we had generated 20.6kWh which is a full 1kWh more than the previous record set at the beginning of April. As per my blog post yesterday about the effect of temperature on solar panel electricity generation the cooler day as well as the breeze look to have contributed.

I think at 20kWh we are now getting very close to the maximum electricity that can be generated in the UK from 3kWp solar panels. I'm hoping we can hit the 21kWh target which would mean each 1kWp of panels had generated 7kWh which seems to be the maximum possible for us.

Maximum solar panel electricity output in UK

Thursday 24 May 2012

How does Temperature Affect Electricity Generated by Solar PV Panels?

How much variation does temperature cause for generating electricity from Solar PV Panels?

With one of the hottest days in the UK so far this year it is interesting to compare the output for a hot sunny day with a cooler sunny day earlier in the year.

The best generating day in April was 19kWh for a clear sunny day with temperature of 12C. Yesterday generated 17kWh for a clear sunny day with a temperature of 27C despite the longer generating time with the lengthening days.

Solar panel output with different temperatures.
As you can see the output was for longer on the blue day (24 May) but the peak was lower than on the green day (2 April) as the temperature was far lower. The equation is the temperature coefficient which for our panels is 0.5% meaning output drops by 0.5% per degree over 25C. So for panels at 35C which is 10 degrees higher the output would be 5% lower.

As another comparison the maximum peak generation was around 2.3kW yesterday but for cooler days this has been as high as 2.5kW and for cloudy days with sunny spells it has peaked as high as 3kW showing the effect that temperature has on solar power generation.

One company was selling a hybrid solar panel that included water heating as well as electricity generation. As a method for cooling the solar panels to improve their efficiency it seems like an effective method based on this data as the water will extract the heat that can then be used for hot water in the house.

Solar panel generation in high temperatures

Wednesday 16 May 2012

May Solar Generation Falls Short: Disappointing Solar Panel performance in May

We are now half way through the month and so far the electricity generated by our solar panels has been disappointing with the poor weather to blame. At the current rate May will be the first month when solar electricity generated has fallen well below target.
May solar panel performance lags behind target

Our record peak electricity generated remains the 1st April when you would actually expect the lengthening days to 22 June to break records consistently. The failure to reach new peaks shows the lack of clear sunny days and the number of rainy days since the hosepipe ban was introduced. Although the sun has shone at different times over the last 6 weeks we have not had a single day when the sun has been out all day with clear blue skies.

How does the Feed in Tariff (FITs) work?

The UK Feed in Tariff was modelled on one introduced in Germany and implemented in the UK from 2010. It pays households that have invested in solar PV power systems a set rate for every kilowatt hour of electricity that they generate as well as a payment for all electricity that they export to the national grid. The export payment is current calculated as "deemed" until smart meters are widely used across the UK. The deemed rate is assumed to be 50% of the electricity generated so if you can use a larger proportion at home then you will still be paid for it. As the export rate is much lower than the FiT rate this won't be a massive saving.
Feed in tariff details in the UK for your solar panels

Depending on your viewpoint the Feed in tariff has either been a huge success leading to large numbers of solar installations to help our CO2 reduction targets and massively cutting the price of solar power or an expensive scheme that has been abused by large players to make money at the expense of all consumers who effectively pay for FITs through a levy on electricity bills.

What is not in dispute is the drop in the costs of installation since 2010. It was common for a 4kWp solar pv system to cost up to £20,000 at the time and as of May 2012 this can cost as little as £7000 now. Putting the cuts in the feed in tariff in context these current prices still give a better return than the original rate with the higher prices.

Tuesday 1 May 2012

Impressive PV Solar Generation Despite Wettest April for 100 Years

April 2012 has been officially recorded as the wettest for over 100 years with rain virtually every day. Our weather station shows a huge 137mm of rain fell during the month compared to 20mm in March 2012. Despite this huge variation we actually generated more electricity from our PV solar panels than in March and were still above the SAP target. March generation was 310 kWh and April had the impressive result of 320kWh despite the rain so we can only imagine how good generation numbers would be with sunny weather.

The April figure of 320 kWh compares to a SAP 2009 estimate of 294kWh and PV-GIS of 330 kWh so is very close to the target. During the month we had some new records for solar electricity generation set with the highest 5 minute average electricity generation at 3.012kW as a result of the intermittent cloud cooling the panels. An output of 3.012kW from 3.01kWp PV solar panels must be about the maximum possible. I guess this was above the rated kWp figures as they are measured at 25C and this month the temperature has been nearer the 10C range. Lower temperatures improve solar power generation as can be seen by the peak generation just after clouds cool the solar panels.