Saturday 31 December 2011

December 2011 - First Full Month of Solar Panel Electricity Generation

As the sun has now set on 31 December 2011 we now have the data for our first full month of solar power generation. Against both estimates using PV-GIS we have either easily beaten or just exceeded the estimated PV generation for the month depending on the values used.

Using the standard PV-GIS solar values the estimate for December was 68 kWh of generation from 3kWp panel and the alternative estimate using satellite solar values was 101 kWh.

Our generation for the month was 105kWh which for December is an excellent result and hopefully a good sign of the performance we should expect from the panels over the next 12 months.

I have now begun the project to automate the collection and loading of the solar PV generation data from the SMA Sunny Boy inverter and will outline the process in another blog post soon.

Thursday 22 December 2011

Solar PV - The Difference Weather Makes for Power Generation!

The difference a day makes, yesterday was cold, dull and wet, a typical December day so our solar PV panels generated very little electricity, a mere 0.65kWh for the whole day.

How difference 24 hours can be! Apart from the sun being so low in the sky today is more like September. Very sunny and warm with temperatures of around 14C, not a typical December day at all. Despite today being the Winter Solstice, the point in the year with the shortest day we have still generated a significant amount of electricity today. As of 3pm we have produced 7kWh and the panels are still generating although it has dropped from the 1800W maximum earlier in the day down to under 200W now. Hopefully this means that from now on into 2012 generation will only increase.

So although salesman might say that all you need for solar panels to produce electricity is daylight and that they generate on dull days too, that is only partly true. For maximum generation you do need sun and lots of it.

Total Solar Electricity Generation for Weather Conditions:

Dull day in December : 0.65 kWh
Sunny day in December : 7.7kWh

For details of he specification of our solar panels installed in Kent UK click here

The Difference Weather Makes for Solar Power Generation

Wednesday 21 December 2011

Solar FITs Cuts Ruled Illegal - High Court Legal Action over Feed in Tariff

Cuts to the Solar PV FITs (Feed in Tariff) have been ruled illegal by the High Court after Legal Action brought by Friends of the Earth and solar PV companies.

The cuts to the Feed in Tariff would have seen the rates slashed from 43.3p per kWh to 21p as of April 2012 for installations after 12 December 2011 despite the consultation that the government initiated not finishing until 23 December.

It hardly seems surprising that this action has been ruled unlawful as cutting a rate while still consulting on it makes no sense at all as I had stated in my blog when the cuts were announced.
Solar FITs Cuts Illegal - High Court Legal Action over Feed in Tariff

Sunday 11 December 2011

December 2011 Performance Figures for Kent PV Solar Panels

Solar PV Panel Daily Outputs - December 2011

These are the daily output figures from our 3.01kWp PV Solar Panel system with Sunny Boy 3000HF inverter.

As of 10 December 2011, the total generated for the month is 44.6 kWh which compares to an estimated total of 68kWh for the whole month so we are ahead of target so far.

  Date  kWh

  01/12/2011  1.426
  02/12/2011  5.981
  03/12/2011  4.874
 04/12/2011  0.596
 05/12/2011  4.233
 06/12/2011  3.311
 07/12/2011  7.033
 08/12/2011  0.7
 09/12/2011  8.542
 10/12/2011  7.936
 11/12/2011  0.888

Output Difference between Sunny and Cloudy Days for Solar PV Generation

I thought it would be interesting to show the difference between the output between two days when one is sunny and the other covered in cloud.

Yesterday was a very sunny day with only a very short spell of cloud. The electricity generated by our 3kWp PV solar panels was over 7kWh. Today is a very dull, wet and cloudy day with no sun. The output has been 0.6kWh so sunny days give at least 10x better solar PV elecricity generation than dull cloudy days, at least in winter.

Sunny day : 7kWh
Cloudy day: 0.6 kWh

Saturday 10 December 2011

Why does my Solar PV Inverter Read Higher/Lower than my Generation Meter?

Having had solar panels installed for nearly a month now it has become clear that there is a difference between the readings from the Sunny Boy inverter and the Landis generation meter so why does my Solar PV Inverter read lower than my Generation Meter? Other people have reported the opposite - that their Solar PV Inverter reads higher than the generation meter?

The reason is that the inverter reading is an estimate based on the electricity it produces but is not an accurate reading of the output. In contrast the generation meter is a calibrated piece of equipment that has to meet certain tolerances and is tested to ensure that the meter is within these tolerances before it leaves the factory.

So the reading on the generation meter is the correct one and the inverter output reading is to give you a good idea of how the panels are performing at any given moment in time.

At present our Sunny Boy 3000HF inverter is showing a reading of 96.1kWh produced but the generation meter is showing 98.33kWh which is just over a 2% difference between them.

Saturday 3 December 2011

Inverter Startup/Kickin Voltage for PV Solar Panels

Does Inverter Startup/Kick In Voltage Matter?

A number of installers throw around the startup voltage of inverters as a sales ploy and seems to be particularly prevalent with Aurora salesmen (it must be part of their training ) . A salesman from PV Solar UK used the argument when trying to sell their system to us but logic said something wasn't right if SMA Sunny Boy, the market leader didn't use that voltage.

The Aurora inverters are shipped with a default startup of 200V, which is actually higher than some other makes, but this is adjustable between 120V & 350V, other makes have adjustable startup settings too. An issue which has come to light in the past is that the saleman will push the 120V startup voltage, but when installed it'll be left at 200V .... why ? Well having too low a startup voltage causes unnecessary switch cycling, particularly in the morning, which can result in premature component failure.

Some data:

Sunrise on 5 Dec 2011 was 07:43 and sunset was 15:49.

Our Sunny Boy inverter started at 0805 producing 12W of electricity and finished at 1545 again producing 12W of electricity. So  the maximum window for increasing production was from 0743 to 0805 and from 1545 to 1549, a total of 22 minutes in the morning and 4 minutes in the evening. Realistically it will only be a few minutes either side that any meaningful electricity can be generated and at less than 12W output (125v/200V) likely to be 7.5W the difference over a year could be a maximum of 3kWh at a cost of early component failure, even the FIT payment of £1.50 isn't worthwhile.

Also when the Sunny Boy inverter starts up at 0805 it is then running for the whole day until sunset. This means that a lower kick in/startup voltage will only have any effect at sunrise and sunset not during daylight hours.

Wednesday 30 November 2011

November PV Solar Panel Output Performance Update

 With a late surge as a result of a brilliant last day to end November the panels gave a final output for the month of 53.02 kWh. As the panels were commissioned late morning on 18th November this was produced over 11.5 days so the estimated production for the whole month of November would be 138 kWh.

So 3.01kWh panels have generated  an average per day of 4.61kWh. This compares well to the SAP calculated estimate of 3.6kWh but is below the figure quoted by PV Solar UK of 4.87kWh which seems overly opimistic - much the same as the rest of their figures!

Monthly PV Solar Panel performance for November

The 11 days of November that the solar panels were generating were a varied mix of sunny, cloudy and a couple of rainy days so appeared to be a typical spread of weather although we are now far more attentive to whether the sun is out or not!

It is now quite noticeable that shading has a significant effect and the graphs produced by the inverter clearly show the drop in output as soon as the panel area has any shade falling on it. I will post some eexperiences of how the shade affects the solar panel output later.

How to View Solar Panel Generation Data via Bluetooth from SMA Sunny Boy 3000HF Inverter

How to View Solar Panel Generation Data via Bluetooth from SMA Sunny Boy 3000HF Inverter 

Having just had our Sungrid PV solar panels installed by Solar Advanced Systems we were keen to be able to monitor the production of electricity by the PV panels without needing to visit the Sunny Boy inverter each time to view the display.
14 Solar panel array - Sungrid PV installation with Sunny Boy 3000HF inverter

SMA Sunny Boy 3000HF (as well as the 2500HF and 4000HF) inverters have the capability to display data using Bluetooth. SMA Sunny Boy supply a device called the Sunny Beam that will show the production from your solar panel system. However this costs around £175 in the UK and there are much cheaper alternatives to the Sunny Beam to show this data on your PC or laptop.

Step 1)

Firstly you need a laptop or PC that has Bluetooth capability. If your PC doesn't have this built in then you can buy an external USB Bluetooth dongle for approx £10. This is one such device from Ebuyer  A class 1 Bluetooth adapter would probably be a better bet than a Class 2 adapter as it will give a much longer range than class 2. The difference between a Bluetooth class 1 range of 100m and class 2 range of 10m is very significant and would mean the difference between being to view the data from any room in your house to only being able to view from the room next to the inverter.

Step 2)

Once the Bluetooth dongle is installed you need to download the free Sunny Explorer software. This is available as a free download from the SMA website.

Step 3)

Install the Sunny Explorer software, let it detect your system. You will need to enter its password which is set as default to 0000.

Step 4)

View your data and download the log files to your PC. By default these are stored in a folder called SMA under the My Documents folder.

Step 5)

Additional tools are also available to analyse and store the data from the SMA Sunny Boy 3000HF./2500HF/4000HF inverter range and I will cover those in another blog post.

You can find more info about viewing your SMA inverter data online without a Sunny Webbox here

Saturday 26 November 2011

An Open Letter to the Government about Solar Panel FiT Cuts

Marc Linch, Director of GreenEnviro Energy Systems has posted an open letter to the national press about the cuts in the Feed In Tariff. He makes some excellent points about the loss of jobs as a result of the FiT being slashed by 50% and the benefits to the UK economy of getting spending on green projects moving.

You can read the full letter here

Friday 25 November 2011

UK Solar PV Panel Performance - Daily Output per kWp

Our PV solar panels have now been installed for almost a week now and over that time the performance has varied considerably as has the weather. On an overcast day we still generated some electricity but it scraped in just under 1kWh.

PV Solar panel performance, daily outputs in Kent UK

Today has been the best performance so far. Despite an initial rainy start, the day quickly cleared to bright sunshine and the panels started generating from 07:40 this morning at 36W, giving a total output for the day of 8.176kWh. For a day in late November this seems to be a very good performance. So far the output recorded on the generation meter has totalled 32.67kWh in just 6 days, ranging from a low of 0.98kWh to todays 8.176kWh.

The maximum peak output at any one point during the day has been 2kW. Again this was achieved today, the highest previous output from our solar panels was 1.5kW which was reached on a number of days this week.

In the 6 days so far we have earnt the grand total of £14 in FIT payments - not a bad start for one of the worst performing months of the year for solar!

It is my intention to publish each month the performance of our solar panels, 3.01kWp from 14 Sungrid 215W panels with SMA Sunny Boy 3000HF inverter to give an indication of what can be achieved as an output from solar panels in Kent UK. Any comparisons with other panels in the UK would be useful, two friends also have now installed solar panels in the local area so I will endeavour to provide figures to compare the different setups and output performance achieved.

Thursday 24 November 2011

Time Lapse Video of PV Solar Panels taken before the Feed In Tariff Cuts happen in December 2011

This is a time lapse video taken of our solar panel installation being fitted by Solar Advanced Systems of Edenbridge Kent. The solar panel array is 14 solar panels of 215W capacity giving a total potential output of 3kWp.

The solar panels are now generating electricity and on 20 November generated a total of 6.46kWh of electricity, somewhat above the quoted average for November of 4.87kWh so it will be interesting to see how they perform over a longer period.

Review of Solar Advanced Systems panel installation.

Wednesday 2 November 2011

Choosing Best Position to install PV Solar Panels in Kent for Maximum FIT Payments

Are you thinking about installing solar panels in Kent to benefit from the FiT (Feed in Tariff) scheme? If you install solar panels you want them in the best position to get the most sun to generate maximum electricity and maximise your FIT payments for best returns. Kent is the Garden of England and has some of the sunniest days in the UK so is ideally positioned to get the best return on your solar panel investment from the payment of Feed In Tariffs.

We have had quotes for installing solar panels on our roof. We have two choices, the lower extension roof or the upper original house roof.

Installing solar panels on the lower roof would be cheaper as the access is much easier than the scaffolding needed for the upper roof. However we have checked the roof at different times of the day and the shading and sun levels are significantly different for the two roofs.

Sun on both roofs first thing in the morning but slight shading on the lower roof to the right hand side

Solar panel positioning to avoid shade for best FIT payments
 You can see on the roof later in the day that the lower roof is almost totally shaded, there is some shade across the upper roof but most of the roof is still covered in sun. We had three options for the panels. With a 3kWp system we could have solar panels fitted on the upper or lower roof or a mix between the two.
Solar panel positioning to avoid shade for best FIT payments
From the photos above we have decided to have the solar panels fitted on the upper roof only. The cost is higher due to the difficult access to the upper roof but from these photos of the shading of the roof the payback should mean that the FiT (Feed in Tariff) payments are significantly higher which will more than offset the increased cost of installing the solar panels on the higher roof.

Panels are now ordered so check back for progress reports on how they are doing!You can view the full article on the blog here