Solar Panel Output - Shortest Day Behind Us!

With the shortest day now behind us we can start to look forward to improving solar panel outputs over the next few months. After the first year with our solar panels it was obvious how much lower the electricity output from solar panels is over the winter months.


Solar Panel Output - Shortest Day Behind Us!

While you may get a solid 16 hours generation during the summer months this can drop to around 6 hours or less during winter especially on very cloudy days. Last year on an extremely cloudy day we barely generated any electricity and on one snowy day had a 0 kWh output.

Luckily even with the poor summer of 2012 we still achieved over 20kWh of electricity generation on 4 days and over 15kWh on 55 days.

In contrast December had no days over 10kWh and only 8 days when above 5kWh was produced.

You can view the full yearly & monthly solar panel output statistics here

Is Solar Panel Investment Still Worthwhile?

Are solar panels still worth buying as an investment or has the sun set on solar power?

We got our solar PV panels last year just before the FIT (Feed In Tariff) was cut from 45p to 21p. At the time it was a great investment and the speculation has been that the investment is no longer worth it. However in that time the price of solar panels has plummeted again so the investment may still be a good one.

I thought it would be useful to compare the numbers we obtained from our first years generation and run them through the calculations for a solar panels based on the new FIT rates and the current price for solar panels.

We paid £9000 for our 3kWp panels and get a FIT rate of 47p per kWh. These generated 3250kWh which produced an income of £1527

Latest panels look to be available for under £6000 for 4kWp panels and on a roof with the same direction as our 3kWp, should be expected to produce 4333kWh of electricity per year. The FIT income from this would be £693 at the 16p rate.

The payback period for our panels is just under 6 years, but the payback for a new installation at the lower FIT rate would still only be just over 8 years so in many ways still a very attractive investment.

When FIT was first introduced the price of solar panels was £16,000 or more for 4kWp so the price drop has meant that the lower FIT retains the same benefits as those at the time Feed in Tariffs were introduced.

What is Annual UK Solar Panel Output from Domestic Installation?

What is the UK Solar Panel Output per year?

We have now had our solar panels for over 12 months so are starting to get year on year comparisons of the output.

Our first year we generated 3095 kWh of electricity from our 3kWp panels (14x Sungrid 245W) but this would have been around 3250 kWh without a loss of 2 weeks generation in August 2012. This is substantially above the SAP2009 estimate of 2479kWh for a 3kWp system.

You can see this graph of Solar Panel Output in the UK which shows the peak at the middle of the day and how the output from solar panels drops towards the end of the day.


What is the UK Solar Panel Output per day?

View UK Solar Panel Output details here



One Year Later: Annual UK Solar Panel Output

After 12 months of of having our solar panels we have now reached that landmark of one year's solar generation. The annual output from our PV Solar Panels has surpassed even our wildest expectations and despite what was estimated to be the worst summer for 100 years we still generated 3095kWh of electricity over the year.

Rain falling on our solar panels

Rain on our solar panels was a common sight this year but even with the appalling summer weather we still generated 30% more than the SAP 2009estimates given with our quotes. The generation varied from 0kWh for a snowy day in February to 20.6kWh for the sunniest summer day. You can read more details here of solar panel UK output records


One Year Later: Annual UK Solar Panel Output

Without the inverter error in August I would expect our solar panels to have generated 3250kWh over the year which would equate to 1083kWh per kWP of solar panels. This is substantially above the normal estimates for the UK of around 800-900kWh of electricity per kWp of installed solar panel capacity.



Frosty solar panels in winter

Why Are Inverter and Generation Meter Readings different?

Why is the inverter reading not the same as the generation meter?

Something we noticed early on with our solar panels was that the inverter and generation meter readings differed. In our case the generation meter reads higher than the inverter but other people have found that the generation meter reading is lower than the inverter.

Over time this can be a significant difference. Approaching the first anniversary of our solar panels being commissioned our generation meter is reading 3079kWh and the inverter reads 3043kWh. The difference is approximately 1% higher reading for the generation meter.

Why is the inverter reading different to the generation meter?

The correct reading is the one on the generation meter as this meter is calibrated and manufactured to strict tolerances. The electricity reading from the inverter should only be considered an estimate and will vary from the true reading from the generation meter.

More solar panel FAQs here

Connect to Sunny Boy Inverter via Bluetooth Using iPhone

Are you trying to connect to your SMA SunnyBoy via Bluetooth using an iPhone? Why does the Sunny Boy inverter not show using Bluetooth on an iPhone?



SMA SunnyBoy Bluetooth iPhone Connection

Unfortunately the Bluetooth on the iPhone does not allow it to connect to the Sunny Boy inverter. In fact the iPhone cannot even detect or display that the Sunny Boy inverter exists as the Bluetooth settings on the iOS software prevent this.

You can detect the SMA Sunny Boy inverter using an Android or Windows phone

Total FIT Payment for Year - Final Payment Now Received

The cheque from British Gas has just arrived, 7 days after submitting the solar panel generation reading which means we have now had our 4 FIT (Feed In Tariff) payments since our solar PV panels were installed in November 2011. It hasn't quite been a year as the final reading was requested on 5th November but we have received FIT payments for 3025 units of electricity produced

Total FIT Payment for Year was £1401.62, this would have been higher apart from the disaster in August when the inverter stopped for 14 days, losing us around 150kWh of electricity generation.



Total FIT Payment for Year - Final Payment Now Received

Despite the exceptionally poor summer months we still have generated over 25% more electricity than the SAP2009 claimed figures which is a great result!