Jamie Taylor

Performance statistics for an ensemble of distributed PV systems in the UK are rare, and there are few publications based on an ensemble representative of the UK PV fleet. This work presents the results of analysing the energy production and the performance of more than 2500 distributed PV systems in the UK monitored for up to 7 years, and provides an overview of the state of the art. We have mapped the annual energy yield of all the PV systems in the database according to the regions of the UK. The mean reported annual energy yield for PV in the UK in 2013 was 910 kWh/kWp, and we assessed the corresponding long-term value as 886 kWh/kWp. The mean value of the yearly-integrated PR for the years 2012-2014 was 84% (with 3% standard deviation). We have shown the presence of seasonal trends in mean monthly PR, with peaks in Spring/Autumn and troughs in Summer/Winter. We have found an increase in the overall performance of PV systems between 6% and 18% from 2004 to 2012, which represents...

In 2012 National Grid, the company responsible for managing the electricity transmission network in the UK, estimated that the UK's energy grid can accommodate up to 22 GW of solar PV generation. Managing such a level of PV penetration on the grid will require advancements in our understanding of the combined energy production of distributed PV. Here we present the results of a study into the length scales over which PV generation time series become decorrelated, a crucial statistic in order to accurately model how PV penetration in the electricity grid impacts at Low, Medium and High Voltage (Transmission) network levels. Using a database containing thousands of real PV generation time series, we have employed simplified geostatistical techniques such as an empirical pseudo-semivariogram with exponential fit in order to study the decorrelation length of PV generation on a half hourly resolution. The decorrelation length under clear-sky conditions is found to extend beyond 350 k...

In June 2015, the UK fleet of solar photovoltaic (PV) systems reached 7.8 GWp of capacity, but there are wide gaps in our understanding of the performance of these systems, which has lead to the conservative limit of 10 GWp being imposed on UK PV capacity by the Department of Energy and Climate Change. Here we present the results of a statistical analysis of real world UK PV systems which donate data to the Microgen Database, of which there are over 7000. The mean yearly-integrated Performance Ratio (PR) of domestic scale UK PV is 83% with a standard deviation of 7%. By considering yearly-integrated PR, we have shown that 4.1 % of systems suffered long-term underperformance relative to their nominal efficiencies during 2013. The mean degradation rate for crystalline Silicon-based PV systems in the UK is-0.8 ± 0.1% per year. The state-of-the-art of UK PV, in terms of technology, manufacturing, and installation-standards, is found to have increased by 1% per year between 2002 and 2013.

We have tried to cast some light on some of the numerous questions concerning the performance of solar PV systems in Europe. We have based our analysis on the operational data monitored at more than 31,000 PV systems in Europe. These installations comprise residential and commercial rooftop PV systems distributed over 9 different countries, including multi-megawatt PV plants installed in the South of Europe. The PV systems were installed between 2006 and 2014. The mean Energy Yield of the PV systems located in the four reference countries are 1115 kWh/kWp for France, 898 kWh/kWp for the UK, 908 kWh/kWp for Belgium, 1450 kWh/kWp for the PV plants in Spain mounted on a static structure, and 2127 kWh/kWp for those mounted on a solar tracker in Spain. We suggest that the typical PR value for the PV systems installed in 2015 is 0.81. We have observed that the performance of the PV systems tends to increase when the peak power of the PV systems increases. We have found significant performance differences as a function of the inverter manufacturer, and the PV module manufacturer and technology. We have found an improvement of the state-of-the-art, in the form of an increase in performance in the yearly integrated PR of around 3 to 4% over the last seven years, which represents an increase of about 0.5% per year.

Performance statistics for an ensemble of distributed PV systems in the UK are rare, and there  are  few  publications  based  on  an  ensemble  representative  of  the  UK  PV  fleet.  This  work presents the results of analysing the energy production and the performance of more than 2500
distributed PV systems in the UK monitored for up to 7 years, and provides an overview of the  state of  the art. We have mapped the annual energy yield of all the PV systems in the database  according to the regions of the UK. The mean reported annual energy yield for PV in the UK in
2013  was  910  kWh/kWp,  and  we  assessed  the  corresponding  long-term  value  as  886  kWh/kWp. The mean value of the yearly-integrated PR for the years 2012-2014 was 84% (with 3% standard deviation). We have shown the presence of seasonal trends in mean monthly PR,
with peaks in Spring/Autumn and troughs in Summer/Winter. We have found an increase in the overall performance of PV systems between 6% and 18% from 2004 to 2012, which represents a clear increasing trend with a mean gradient of 1.5%/year.

In  2012  National  Grid,  the  company  responsible  for  managing  the  electricity  transmission network in the UK, estimated that the UK’s energy grid can accommodate up to 22 GW of solar  PV generation. Managing such a level of PV penetration on the grid will require advancements  in our understanding of the combined energy production of distributed PV. Here we present the  results  of  a  study  into  the  length  scales  over  which  PV  generation  time  series  become  decorrelated, a crucial statistic in order to accurately model how PV penetration in the electricity  grid  impacts  at  Low,  Medium  and  High  Voltage  (Transmission)  network  levels.  Using  a database containing thousands of real PV generation time series, we have employed simplified geostatistical techniques such as an empirical pseudo semivariogram with  exponential fit in  order  to  study  the  decorrelation  length  of  PV  generation  on  a  half  hourly  resolution.  The  decorrelation length under clear-sky conditions is found to extend beyond 350 km, whilst under  variable sky conditions PV generation time series are found to decorrelate after 15 km. We have qualitatively identified the presence ofstochastic decorrelation at all length scales.