Real Solar PV: data and experiences from a real solar photovoltaic installation

Data

The installation first generated on 2 December 2011 and readings from the generation meter are used to update the various charts and tables each month.

SAP calculation

Under the MCS accreditation scheme (1), installers are required to use the Government's SAP (Standard Assessment Procedure) calculation to ensure parity across quotations. Whilst this takes account of roof orientation, slope and any shading, it doesn't allow for different latitudes, leading to the north of the country being rated on a par with the south. The SAP calculation for this installation shows an annual predicted output of 2914kWh.

A more accurate figure can be obtained by using the calculator made available by the Photovoltaic Geographical Information System (PVGIS) (2). This showed a predicted annual output of 3140kWh at the time of installation but revised data now indicates 3210kWh. A third calculation, using the PVSOL calculator, indicates an output of 3050kWh.

SAP calculation *

PVGIS calculation *

* The above tables assume initial FiT and export rates of 43.3p and 3.1p increasing at 2.5% per annum, imported energy prices increasing at 4% per annum on a base 12p per kWh.

The charts and calculations below are based on the SAP calculation.

Predicted output v 2020-21 actual

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2020-21 actual

Predicted Feed in Tariff income v actual

Predicted FiT income (£)

Actual FiT income (£)

Electricity consumption from the grid pre PV installation v post PV installation: running average (kWh)

Interpretation of data presented in this chart is more difficult than that for others as consumption can vary quite widely year-on-year as a consequence of changes in such variables as occupancy patterns and the presence of electrical appliances. Never-the-less, the data presented is real data from a real installation.

Electricity consumption from the grid pre PV installation (kWh)

Electricity consumption from the grid post PV installation, running average (kWh)

Cumulative return on investment 2020-21 (£)

The graph displays cumulative income calculated on the Feed in Tariff and an additional amount for the 50% of generated energy which is deemed to be exported. At the time the system was commissioned, the Feed in Tariff was 43.3p per kWh and the Export Tariff was 3.1p per kWh. Both are increased each April by an amount which reflects the increase in the Retail Price Index over the previous 12 months. Savings made from reductions in imported energy are not included.

Graph of cumulative return on investment (£)

Daily generation, September 2021

Actual daily generation (kWh), September 2021

Predicted monthly average (kWh), September 2021

Current rolling average (kWh), September 2021

Predicted rolling average (kWh), September 2021

Snow on panels

Variation from predicted generation (%)

Variation to date

Variation this month

Daily generation (kWh) Year 10, 2020-21

Actual daily generation (kWh), Year 10

Predicted rolling average (kWh), Year 10

Daily peak (kW) Year 10, 2020-21

Actual daily peak (kW), Year 10

Average daily peak (kW), Year 10

Daily generation start, peak and stop times, and generation period, Year 10, 2020-21

Daily generation start, peak and stop times Year 10, 2020-21

Daily generation start time, Year 10 (time: left hand axis)

Daily generation peak time, Year 10 (time: left hand axis)

Daily generation stop time, Year 10 (time: left hand axis)

Daily generation period, Year 10 (hours: right hand axis)
[All times are GMT]

Earliest start: 04:00 on several dates
Latest start: 16:20 on several dates

Earliest finish: 12:20 on several dates
Latest finish: 22:00 on several dates

Longest period of generation: 16 hours 50 minutes on several dates
Shortest period of generation: 0 hours 10 minutes on 21 January 2015

Earliest maximum: 08:30
Latest maximum: 19:20
Most frequent maximum: 13:10

Days above predicted average:56.9%
Days below predicted average:43.1%

Total generation, income, savings and return on capital to date

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

31755

34732

+2,977

+9.4%

SAP

28827

34732

+5,905

+20.5%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£14242

£18130

+£3888

+27.3%

SAP

£12929

£18130

+£5201

+40.2%

Import savings (completed months)

£3338

44%

Total income to date

£21468

Return on capital

+19.9% (excluding import savings)

+23.6% (including import savings)

Daily maximum, minimum*, intra-day peak** and average generation (kWh), with monthly totals (kWh) and variation (%)

* Several minima of zero when the panels were entirely covered in snow have been ignored
** Output is recorded by the system every 10 minutes and so transient highs are missed. Readings in excess of 4kW have been regularly observed. All times are GMT.

Maximum

Minimum

Intra-day peak

Average

Total

Variation

Since commissioning

29.448 on 12 Jun 2021

0.000 on 19 Jan 2013

3.978 at 14:50 on 16 May 2012

9.672

34732

+20.5%

2021

September

17.843 on 20 September

2.321 on 14 September

3.204 at 14:20 on 29 September

10.231

306.916

+20.8%

August

22.849 on 3 August

4.924 on 21 August

3.462 at 15:10 on 17 August

12.635

391.680

+15.9%

July

26.182 on 1 July

5.115 on 30 July

3.762 at 15:40 on 28 July

16.528

512.373

+26.7%

June

29.448 on 12 June

6.346 on 21 June

3.780 at 14:00 on 19 June

18.055

541.659

+34.7%

May

27.931 on 30 May

5.446 on 3 May

3.810 at 13:40 on 7 May

14.938

463.087

+10.8%

April

25.115 on 22 April

5.494 on 1 April

3.594 at 14:10 on 25 April

17.259

517.763

+53.7%

March

18.763 on 30 March

1.623 on 10 March

3.282 at 13:20 on 26 March

8.602

289.567

+17.5%

February

14.123 on 28 February

0.020 on 2 February

2.730 at 13:10 on 25 February

5.097

142.715

+19.2%

January

7.577 on 25 January

0.000 on 14 January

1.746 at 13:40 on 23 January

2.184

69.686

-5.5%

2020

December

4.580 on 1 December

0.222 on 13 December

1.554 at 14:10 on 25 December

1.969

61.052

-1.4%

November

8.160 on 4 November

0.496 on 29 November

2.220 at 14:00 on 4 November

3.046

91.384

+2.9%

October

10.437 on 1 October

0.724 on 3 October

2.778 at 12:40 on 5 October

5.113

158.496

-2.4%

September

18.034 on 14 September

3.047 on 16 September

3.234 at 14:40 on 6 September

11.037

331.101

+30.3%

August

22.986 on 24 August

2.408 on 16 August

3.300 at 14:40 on 22 August

12.303

381.405

+12.8%

July

24.056 on 19 July

6.292 on 2 July

3.768 at 13:30 on 22 July

14.050

435.545

+7.7%

June

27.365 on 25 June

3.534 on 12 June

3.678 at 13:10 on 13 June

14.657

439.716

+9.3%

May

28.070 on 25 May

9.259 on 18 May

3.762 at 14:30 on 19 May

19.977

619.282

+48.2%

April

25.627 on 20 April

5.018 on 29 April

3.774 at 14:00 on 2 April

17.316

519.477

+54.2%

March

20.262 on 26 March

3.553 on 10 March

3.468 at 12:20 on 29 March

11.133

337.225

+36.8%

February

13.569 on 27 February

0.845 on 15 February

2.628 at 14:20 on 23 February

5.094

142.623

+15.0%

January

5.907 on 19 January

0.476 on 11 January

2.058 at 13:10 on 18 January

2.643

81.930

+11.1%

2019

December

4.975 on 9 December

0.281 on 12 December

1.446 at 13:50 on 8 December

2.366

42.583

+7.1%

November

6.390 on 18 November

0.346 on 25 November

1.818 at 13:10 on 13 November

2.409

72.281

-18.6%

October

17.459 on 2 October

1.954 on 13 October

2.682 at 14:10 on 2 October

6.195

192.035

+18.3%

September

19.253 on 13 September

2.128 on 24 September

3.294 at 13:30 on 1 September

11.375

341.252

+34.3%

August

22.201 on 13 August

2.796 on 16 August

3.552 at 13:20 on 8 August

14.665

454.630

+34.5%

July

25.080 on 23 July

1.740 on 27 July

3.552 at 13:20 on 1 July

15.433

478.416

+18.3%

June

28.163 on 27 June

4.464 on 25 June

3.606 at 15:00 on 21 June

14.642

439.271

+9.2%

May

27.260 on 24 May

5.247 on 8 May

3.744 at 11:40 on 20 May

15.809

490.084

+17.3%

April

23.256 on 21 April

4.915 on 8 April

3.354 at 14:30 on 2 April

14.883

446.501

+32.5%

March

20.557 on 29 March

2.926 on 6 March

3.282 at 12:20 on 26 March

9.391

312.806

+26.9%

February

13.373 on 27 February

1.012 on 1 February

2.484 at 12:40 on 11 February

6.963

194.969

+62.9%

January

8.724 on 28 January

0.296 on 7 January

2.040 at 13:50 on 30 January

2.811

87.127

+18.2%

2018

December

4.718 on 9 December

0.134 on 18 December

1.800 at 13:00 on 7 December

1.883

58.367

-5.7%

November

9.221 on 2 November

0.254 on 22 November

2.766 at 11:30 on 3 November

2.916

87.490

-1.5%

October

13.185 on 18 October

0.896 on 12 October

3.384 at 14:10 on 1 October

6.884

213.410

+31.4%

September

17.593 on 12 September

4.500 on 8 September

3.150 at 13:10 on 23 September

10.967

329.014

+29.5%

August

22.025 on 5 August

3.938 on 26 August

3.444 at 13:40 on 24 August

13.094

405.907

+20.1%

July

27.403 on 2 July

3.659 on 29 July

3.426 at 13:00 on 10 July

18.059

559.821

+38.4%

June

28.774 on 22 June

7.483 on 4 June

3.744 at 14:40 on 18 June

19.260

577.794

+43.6%

May

27.334 on 13 May

3.213 on 30 May

3.666 at 12:50 on 10 May

19.455

603.095

+44.3%

April

22.934 on 20 April

1.216 on 2 April

3.588 at 14:00 on 25 April

10.743

322.300

-4.3%

March

17.421 on 25 March

0.008 on 1 March

3.228 at 12:50 on 19 March

6.484

202.486

-17.9%

February

12.947 on 25 February

0.060 on 28 February

2.658 at 11:50 on 25 February

5.295

148.255

+23.8%

January

6.367 on 31 January

0.134 on 9 January

1.788 at 12:40 on 29 January

2.493

77.274

+4.8%

2017

December

5.218 on 1 December

0.011 on 29 December

1.782 at 14:20 on 27 December

2.205

68.365

+10.4%

November

8.990 on 5 November

0.482 on 22 November

2.208 at 13:10 on 5 November

3.961

118.833

+33.8%

October

14.440 on 5 October

0.843 on 26 October

2.586 at 12:30 on 2 October

5.216

161.691

-0.4%

September

15.985 on 13 September

3.525 on 25 September

3.120 at 12:40 on 16 September

9.241

277.244

+9.1%

August

22.659 on 5 August

6.107 on 8 August

3.654 at 13:50 on 19 August

14.376

445.670

+31.9%

July

28.034 on 2 July

4.825 on 11 July

3.720 at 13:40 on 1 July

16.307

505.514

+25.0%

June

27.280 on 18 June

2.775 on 23 June

3.618 at 13:40 on 7 June

13.860

415.785

+3.4%

May

26.781 on 26 May

2.113 on 29 May

3.726 at 14:20 on 27 May

16.050

497.549

+19.1%

April

24.109 on 23 April

5.876 on 14 April

3.786 at 13:50 on 15 April

13.781

413.427

+22.7%

March

19.670 on 24 March

1.923 on 22 March

3.270 at 13:30 on 31 March

9.942

303.129

+23.0%

February

9.690 on 24 February

0.035 on 13 February

2.526 at 12:20 on 24 February

3.709

103.842

-13.3%

January

8.200 on 25 January

0.332 on 6 January

1.704 at 13:30 on 25 January

2.365

73.330

-0.5%

2016

December

4.950 on 29 December

0.260 on 23 December

1.440 at 13:40 on 4 December

2.094

64.902

+4.8%

November

7.233 on 2 November

0.175 on 9 November

1.956 at 12:00 on 4 November

3.392

101.773

+14.6%

October

14.909 on 3 October

1.835 on 30 October

3.024 at 12:40 on 2 October

6.304

195.429

+20.4%

September

17.739 on 11 September

3.330 on 3 September

3.084 at 12:30 on 11 September

10.628

318.829

+25.5%

August

21.795 on 16 August

3.071 on 25 August

3.570 at 15:10 on 4 August

14.050

435.548

+28.9%

July

24.821 on 3 July

6.390 on 9 July

3.768 at 13:20 on 30 July

16.205

502.352

+24.2%

June

26.274 on 6 June

5.395 on 1 June

3.708 at 13:40 on 25 June

14.505

435.137

+8.2%

May

26.704 on 16 May

5.281 on 25 May

3.648 at 13:40 on 3 May

16.404

508.520

+21.7%

April

24.227 on 20 April

2.491 on 12 April

3.756 at 12:50 on 30 April

13.191

395.732

+17.5%

March

18.729 on 31 March

0.042 on 4 March

3.414 at 13:00 on 31 March

7.626

255.669

+3.7%

February

12.344 on 23 February

0.823 on 6 February

2.688 at 13:50 on 23 February

5.989

167.043

+40.1%

January

6.066 on 15 January

0.050 on 17 January

1.674 at 13:40 on 29 January

1.987

61.582

-16.5%

2015

December

4.811 on 29 December

0.087 on 12 December

1.404 at 12:10 on 29 December

1.573

48.766

-21.2%

November

7.895 on 1 November

0.286 on 30 November

1.980 at 12:50 on 16 November

2.453

73.596

-17.1%

October

15.595 on 1 October

0.800 on 28 October

2.688 at 13:30 on 6 October

6.111

189.433

+16.7%

September

21.110 on 6 September

4.053 on 8 September

3.600 at 13:20 on 4 September

11.437

343.108

+35.0%

August

20.879 on 27 August

2.511 on 14 August

3.546 at 13:50 on 15 August

13.356

414.037

+22.5%

July

27.213 on 15 July

8.135 on 27 July

3.636 at 13:00 on 19 July

16.036

497.103

+22.9%

June

28.448 on 10 June

5.696 on 14 June

3.846 at 14:10 on 21 June

18.433

552.994

+37.5%

May

24.711 on 26 May

7.867 on 2 May

3.894 at 14:00 on 19 May

15.936

494.005

+18.2%

April

24.105 on 21 April

3.745 on 3 April

3.798 at 13:00 on 11 April

16.671

500.129

+48.5%

March

17.068 on 31 March

2.188 on 9 March

3.180 at 13:40 on 31 March

9.274

297.817

+20.8%

February

11.670 on 23 February

0.665 on 13 February

2.814 at 14:10 on 27 February

5.494

153.843

+28.5%

January

7.522 on 30 January

0.000 on 21 January

1.920 at 12:20 on 31 January

2.574

79.800

+8.2%

2014

December

5.532 on 3 December

0.313 on 21 December

1.500 at 12:40 on 13 December

2.594

80.404

+29.9%

November

10.093 on 3 November

0.332 on 27 November

2.058 at 13:10 on 4 November

2.785

83.548

-5.9%

October

13.153 on 2 October

0.798 on 27 October

2.730 at 13:40 on 4 October

5.682

176.143

+8.5%

September

19.783 on 7 September

2.520 on 19 September

3.066 at 11:40 on 2 September

9.658

289.753

+14.0%

August

24.811 on 4 August

5.424 on 25 August

3.588 at 13:40 on 14 August

14.455

448.092

+32.6%

July

26.938 on 9 July

7.033 on 19 July

3.738 at 12:20 on 13 July

18.236

565.325

+39.8%

June

25.940 on 12 June

5.270 on 27 June

3.576 at 12:30 on 12 June

15.257

457.723

+13.8%

May

26.509 on 17 May

2.018 on 1 May

3.888 at 13:50 on 13 May

14.129

438.000

+4.8%

April

24.056 on 18 April

2.311 on 3 April

3.480 at 12:40 on 14 April

11.688

350.647

+4.1%

March

19.420 on 24 March

2.491 on 25 March

3.156 at 12:50 on 24 March

9.761

302.581

+22.7%

February

11.095 on 27 February

0.675 on 5 February

2.958 at 13:30 on 25 February

5.445

152.447

+27.3%

January

6.225 on 20 January

0.155 on 1 January

2.154 at 13:10 on 23 January

2.555

79.211

+7.4%

2013

December

4.509 on 29 December

0.175 on 23 December

1.554 at 13:10 on 4 December

2.076

64.359

+4.0%

November

10.319 on 4 November

1.296 on 11 November

2.046 at 14:30 on 5 November

4.387

131.611

+48.2%

October

12.662 on 6 October

0.280 on 12 October

3.558 at 14:50 on 10 October

5.455

169.109

+4.1%

September

16.857 on 22 September

2.759 on 6 September

3.450 at 14:00 on 9 September

9.482

284.471

+12.0%

August

22.105 on 18 August

4.711 on 24 August

3.564 at 13:40 on 31 August

14.509

449.785

+33.1%

July

26.068 on 5 July

7.215 on 2 July

3.690 at 14:10 on 3 July

18.363

569.240

+40.8%

June

27.694 on 7 June

8.170 on 11 June

3.600 at 14:10 on 2 June

17.790

533.702

+32.7%

May

27.890 on 25 May

3.661 on 18 May

3.810 at 11:50 on 16 May

14.914

462.341

+10.6%

April

23.378 on 20 April

5.114 on 11 April

3.882 at 12:30 on 26 April

13.653

409.588

+21.6%

March

16.549 on 29 March

0.428 on 8 March

3.624 at 13:40 on 30 March

7.067

219.091

-11.1%

February

13.841 on 28 February

0.651 on 13 February

2.370 at 11:50 on 27 February

5.183

145.130

+15.0%

January

6.749 on 27 January

0.009 on 14 January

1.836 at 12:50 on 27 January

1.386

42.979

-41.7%

2012

December

6.166 on 2 December

0.042 on 14 December

1.632 at 12:30 on 5 December

2.231

69.149

+11.7%

November

7.846 on 5 November

0.548 on 20 November

2.148 at 12:10 on 2 November

3.617

108.502

+22.2%

October

13.626 on 7 October

0.645 on 24 October

2.922 at 12:20 on 5 October

6.446

199.813

+23.1%

September

18.738 on 8 September

1.329 on 24 September

3.240 at 13:20 on 2 September

11.124

333.716

+31.3%

August

22.868 on 8 August

4.611 on 27 August

3.666 at 13:00 on 3 August

12.319

381.902

+13.0%

July

26.849 on 11 July

1.944 on 6 July

3.750 at 13:10 on 12 July

13.846

429.231

+6.1%

June

23.15 on 26 June

4.298 on 21 June

3.852 at 15:40 on 25 June

12.512

375.352

-6.7%

May

27.875 on 18 May

3.736 on 10 May

3.978 at 14:50 on 16 May

17.147

531.545

+27.2%

April

22.855 on 10 April

1.867 on 1 April

3.738 at 15:00 on 21 April

11.142

334.262

-0.8%

March

18.361 on 26 March

1.731 on 4 March

2.814 at 16:00 on 30 March

10.772

333.941

+35.5%

February

12.25 on 19 February

0.087 on 5 February

2.172 at 12:30 on 15 February

4.090

118.614

-4.3%

January

6.968 on 28 January

0.403 on 1 January

1.782 at 13:50 on 26 January

2.877

89.190

+21.0%

2011

December

5.037 on 18 December

0.281 on 23 December

1.572 at 12:20 on 24 December

1.656

57.375

-17.1%

Historic monthly generation totals

Historic daily generation totals

Year 9 (2019-20) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3206.471

3601.028

+394.557

+12.3%

SAP

2910.796

3601.028

+690.232

+23.7%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1438.10

£2083.58

+£645.48

+44.9%

SAP

£1305.49

£2083.58

+£778.09

+59.6%

Total import savings (Year 9)

£232

29.43%

Return on capital at end of Year 9

+21.8% (excluding import savings)

+25.5% (including import savings)

Predicted output v 2019-20 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2019-20 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2019-20 (£)

Daily generation (kWh) 2019-20

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2019-20

Daily generation start time, Year 9 (time: left hand axis)

Daily generation peak time, Year 9 (time: left hand axis)

Daily generation stop time, Year 9 (time: left hand axis)

Daily generation period, Year 9 (hours: right hand axis)
[All times are GMT]

Year 8 (2018-19) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3311.710

+109.950

+3.4%

SAP

2906.520

3311.710

+405.190

+13.9%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1991.18

+£555.20

+38.7%

SAP

£1303.57

£1991.18

+£687.60

+52.7%

Total import savings (Year 8)

£277

35.19%

Return on capital at end of Year 8

+18.7% (excluding import savings)

+22.8% (including import savings)

Predicted output v 2018-19 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2018-19 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2018-19 (£)

Daily generation (kWh) 2018-19

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2018-19

Daily generation start time, Year 8 (time: left hand axis)

Daily generation peak time, Year 8 (time: left hand axis)

Daily generation stop time, Year 8 (time: left hand axis)

Daily generation period, Year 8 (hours: right hand axis)
[All times are GMT]

Year 7 (2017-18) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3595.211

+393.451

+12.29%

SAP

2906.520

3595.211

+688.691

+23.69%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1952.65

+£516.66

+35.98%

SAP

£1303.57

£1952.65

+£649.07

+49.79%

Total import savings (Year 7)

£377

47.9%

Return on capital at end of Year 7

+18.7% (excluding import savings)

+22.8% (including import savings)

Predicted output v 2017-18 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2017-18 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2017-18 (£)

Daily generation (kWh) 2017-18

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2017-18

Daily generation start time, Year 7 (time: left hand axis)

Daily generation peak time, Year 7 (time: left hand axis)

Daily generation stop time, Year 7 (time: left hand axis)

Daily generation period, Year 7 (hours: right hand axis)
[All times are GMT]

Year 6 (2016-17) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3380.916

+179.156

+5.59%

SAP

2906.520

3380.916

+474.396

+16.32%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1705.06

+£269.07

+18.74%

SAP

£1303.57

£1705.06

+£401.48

+30.8%

Total import savings (Year 6)

£368

46.8%

Return on capital at end of Year 6

+21.4% (excluding import savings)

+25.5% (including import savings)

Predicted output v 2016-17 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2016-17 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2016-17 (£)

Daily generation (kWh) 2016-17

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2016-17

Daily generation start time, Year 6 (time: left hand axis)

Daily generation peak time, Year 6 (time: left hand axis)

Daily generation stop time, Year 6 (time: left hand axis)

Daily generation period, Year 6 (hours: right hand axis)
[All times are GMT]

Year 5 (2015-16) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3206.471

3426.380

+219.909

+6.85%

SAP

2906.520

3426.380

+519.86

+17.89%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1438.10

£1728.14

+£290.04

+20.2%

SAP

£1305.49

£1728.14

+£422.65

+32.4%

Total import savings (Year 5)

£310

39.41%

Return on capital at end of Year 5

+18.1% (excluding import savings)

+22.2% (including import savings)

Predicted output v 2015-16 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2015-16 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2015-16 (£)

Daily generation (kWh) 2015-16

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2015-16

Daily generation start time, Year 5 (time: left hand axis)

Daily generation peak time, Year 5 (time: left hand axis)

Daily generation stop time, Year 5 (time: left hand axis)

Daily generation period, Year 5 (hours: right hand axis)
[All times are GMT]

Year 4 (2014-15) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3676.269

+474.509

+14.8%

SAP

2906.520

3676.269

+769.749

+26.5%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1853.86

+£417.87

+22.5%

SAP

£1303.57

£1853.86

+£550.28

+29.7%

Total import savings (Year 4)

£415

52.76%

Return on capital at end of Year 4

+18.3% (excluding import savings)

+22.5% (including import savings)

Predicted output v 2014-15 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2014-15 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2014-15 (£)

Daily generation (kWh) 2014-15

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2014-15

Daily generation start time, Year 4 (time: left hand axis)

Daily generation peak time, Year 4 (time: left hand axis)

Daily generation stop time, Year 4 (time: left hand axis)

Daily generation period, Year 4 (hours: right hand axis)
[All times are GMT]

Year 3 (2013-14) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3407.829

+206.069

+6.4%

SAP

2906.520

3407.829

+501.309

+17.2%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1688.09

+£252.11

+14.9%

SAP

£1303.57

£1688.09

+£384.52

+22.8%

Total import savings (year 3)

£393

49.92%

Return on capital at end of year 3

+17.8% (excluding import savings)

+21.0% (including import savings)

Predicted output v 2013-14 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2013-14 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2013-14 (£)

Daily generation (kWh) 2013-14

Actual daily generation (kWh)

Predicted rolling average (kWh)

Daily generation start, peak and stop times, and generation period, 2013-14

Daily generation start time, year 3 (time: left hand axis)

Daily generation peak time, year 3 (time: left hand axis)

Daily generation stop time, year 3 (time: left hand axis)

Daily generation period, year 3 (hours: right hand axis)
[All times are GMT]

Year 2 (2012-13) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3201.760

3486.196

+284.436

+8.9%

SAP

2906.520

3486.196

+579.676

+19.9%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1435.99

£1682.46

+£246.47

+17.2%

SAP

£1303.57

£1682.46

+£378.89

+29.1%

Total import savings (year 2)

£389

49.36%

Return on capital at end of year 2

+17.4% (excluding import savings)

+21.6% (including import savings)

Predicted output v 2012-13 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2012-13 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2012-13 (£)

Daily generation (kWh) 2012-13

Actual daily generation (kWh)

Predicted rolling average (kWh)

Year 1 (2011-12) Summary

Generation (kWh)

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

3206.470

3293.443

+86.973

+2.7%

SAP

2910.796

3293.443

+382.647

+13.1%

Income

Calculation

Predicted

Actual

Variation

% Variation

PVGIS

£1438.10

£1535.04

+£96.94

+6.7%

SAP

£1305.49

£1535.04

+£229.55

+17.6%

Total import savings (year 1)

£390

49.51%

Return on capital at end of year 1

+16.6% (excluding import savings)

+20.8% (including import savings)

Predicted output v 2011-12 actual output

Predicted output (kWh)

Actual output (kWh)

Predicted Feed in Tariff income v 2011-12 actual

Predicted FiT income (£)

Actual FiT income (£)

Cumulative return on investment 2011-12 (£)

Daily generation (kWh) 2011-12

Actual daily generation (kWh)

Predicted rolling average (kWh)

(1) Microgeneration Certification Scheme
(2) Photovoltaic Geographical Information System (PVGIS) calculator