NEW MCS Guide on PV Performance Estimation

[snoopdog]

Hi all I was wondering if any of you had a chance to look at the new Performance Estimation

Just done a trial and I was wondering if you agree with my calc's


A 4 Kwp system no shading, 20 degrees off south (almost South West) pitch 35 degrees we are a CO7 postcode Table 12 ( page 111 in the guide )


Annual AC output (kWh) = kWp x Kk x SF Therefore 4 x 949 x 1 = 3796 Kwp


Sap 2009 = .8 x kWp x S x ZPV Therfore .8 x 4 x 1 1027 = 3286.4 Kwp

Perhaps some one could confirm my I am correct and also that we can illustrate the estimated annual yield as 3796 Kwp in our payback cals's and be in compliance with REAL and the MCS scheme.

Look forward to your replies

 

[Ian-LS]

Hi all I was wondering if any of you had a chance to look at the new Performance Estimation

Just done a trial and I was wondering if you agree with my calc's


A 4 Kwp system no shading, 20 degrees off south (almost South West) pitch 35 degrees we are a CO7 postcode Table 12 ( page 111 in the guide )


Annual AC output (kWh) = kWp x Kk x SF Therefore 4 x 949 x 1 = 3796 Kwp


Sap 2009 = .8 x kWp x S x ZPV Therfore .8 x 4 x 1 1027 = 3286.4 Kwp

Perhaps some one could confirm my I am correct and also that we can illustrate the estimated annual yield as 3796 Kwp in our payback cals's and be in compliance with REAL and the MCS scheme.

Look forward to your replies

3796 kWh you mean not kWp. If you state kWp not kWh then I don't think you'll be in compliance with REAL and MCS. Other than that it sounds like the right kind of figure the CO postcode should get.

 

[whinmoor]

I just did a trial using the software at Paperclip: PaperClip :: SAP Calculator

Using your example data it gave: 3037kWh p.a.

Not sure if this is correct or not. It seems very low to me.

 

[Ian-LS]

That PV paper clip still has inverter losses at 20 % which is why the output is low. Its basic calculation of the irradiation times the kWp of panels x the shading factor is it not?

 

[snoopdog]

3796 kWh you mean not kWp. If you state kWp not kWh then I don't think you'll be in compliance with REAL and MCS. Other than that it sounds like the right kind of figure the CO postcode should get.

Sorry your totally correct it was a mad moment I was having should have been 3796 kWh.

Thanks Ian, the point I was trying to make as well under the new MCS Guide as soon as we all start using it the whole thing looks a lot better for the doubtful customer , but within the REAL rules

 

[whinmoor]

That PV paper clip still has inverter losses at 20 % which is why the output is low. Its basic calculation of the irradiation times the kWp of panels x the shading factor is it not?

That would explain the discrepancy. I can't see inverter losses mentioned in the small print and 20% seems like a pretty serious mis-match! Hope they can rectify it soon to be more accurate.

 

[Ian-LS]

0.8 is the factor used in SAP 2009 so I guess its just been left in cause the dog ate it

 

[Vegelen]

PVGIS estimates of solar electricity generation ​ Location: 51�54'41" North, 0�59'7" East, Elevation: 36 m a.s.l.,

Solar radiation database used: PVGIS-CMSAF Nominal power of the PV system: 4.0 kW (crystalline silicon) Estimated losses due to temperature and low irradiance: 11.7% (using local ambient temperature) Estimated loss due to angular reflectance effects: 3.0% Other losses (cables, inverter etc.): 14.0% Combined PV system losses: 26.3%

Fixed system: inclination=35�, orientation=20� Month E[SUB]d[/SUB] E[SUB]m[/SUB] H[SUB]d[/SUB] H[SUB]m[/SUB] Jan 4.37 136 1.37 42.3 Feb 6.96 195 2.22 62.2 Mar 10.50 324 3.44 107 Apr 15.30 458 5.20 156 May 15.80 490 5.49 170 Jun 16.10 483 5.67 170 Jul 15.40 477 5.46 169 Aug 13.80 428 4.88 151 Sep 12.10 362 4.16 125 Oct 8.56 265 2.85 88.3 Nov 5.80 174 1.85 55.4 Dec 3.94 122 1.22 38.0 Yearly average 10.7 326 3.65 111 Total for year 3920 1330

 

[Ian-LS]

PVGIS estimates of solar electricity generation​ Location: 51�54'41" North, 0�59'7" East, Elevation: 36 m a.s.l.,

Solar radiation database used: PVGIS-CMSAF Nominal power of the PV system: 4.0 kW (crystalline silicon) Estimated losses due to temperature and low irradiance: 7.4% (using local ambient temperature) Estimated loss due to angular reflectance effects: 3.0% Other losses (cables, inverter etc.): 14.0% Combined PV system losses: 22.7%

Fixed system: inclination=35�, orientation=20� Month E[SUB]d[/SUB] E[SUB]m[/SUB] H[SUB]d[/SUB] H[SUB]m[/SUB] Jan 4.53 140 1.37 42.3 Feb 7.25 203 2.22 62.2 Mar 11.00 340 3.44 107 Apr 16.10 484 5.20 156 May 16.70 517 5.49 170 Jun 17.00 509 5.67 170 Jul 16.20 503 5.46 169 Aug 14.50 451 4.88 151 Sep 12.70 381 4.16 125 Oct 8.95 278 2.85 88.3 Nov 6.01 180 1.85 55.4 Dec 4.07 126 1.22 38.0 Yearly average 11.3 343 3.65 111 Total for year 4110 1330

E[SUB]d[/SUB]: Average daily electricity production from the given system (kWh) E[SUB]m[/SUB]: Average monthly electricity production from the given system (kWh) H[SUB]d[/SUB]: Average daily sum of global irradiation per square meter received by the modules of the given system (kWh/m[SUP]2[/SUP]) H[SUB]m[/SUB]: Average sum of global irradiation per square meter received by the modules of the given system (kWh/m[SUP]2[/SUP])

Pretty sure you have forgot to change it to building integrated rather than free standing, so it will overestimate production. Unless the system is free standing of course!