Discuss New MCS MIS3002 and PV Guide in the Solar PV Forum | Solar Panels Forum area at ElectriciansForums.net

You are incorrect. the SAP kWh/kWp for zone 12 for south facing 35 degree roof is 961 kWh/kWp. Assuming no shading the prediction would be 961 kWh x 4 kWp = 3884 kWh

So in increase of 400 kWh or so

It will make the selling of PV systems easier to an extent. Harder for places like Inverness for those who relied in SAP 2009, we haven't relied on SAP calcs at all up till now although do provide them in our quotes but not used for our performance estimates
 
Haven't looked at the new guide properly yet (in a moment of wanton frivolity, I ordered a hard copy for £9.99 off the Elecsa website so will wait for that to arrive and get stuck in with a cuppa) but am I correct in assuming that the shading assessment is more involved at the survey stage? If we will be doing more work in order to submit a quote and component prices are creeping up too, will we see installation prices increase to compensate? Will this damper customer enthusiasm all over again?
 
It certainly looks like a shading analysis needs to be performed at the survey stage, preferably from a window below where the array will go. So, yes, more paperwork. Looks like this can be excluded if there's clearly no shading.
 
We have quite often done this with a shading selector tool to assess the shading. Its fairly simple to do but you have to be careful to take into account the orientation of the roof, an east facing system with shading up until 10 am throughout the year would have a massive impact on the system potentially making it unsuitable. Whereas a south facing roof with shading up till 10 am the shading losses would be in the region of 5-10% roughly.
 
hmm.

There's a few things I'm not happy with in there...

Performance estimates are basically just an updating of the flawed SAP methods and are only marginally better, but fiendishly complex - they're certainly not going to stop any of the dodgy lying gits in the shiny suits from lying through their teeth about performance estimates then going bust before the liability claims roll in. As I read this they're at best around 15-20% accurate once you take into account the +/- 10% accuracy of the shading estimate, and the 15-20% varation from the average sunlight levels there is for our region (East Penines) between the east coast, and the Penine areas.

Fair enough if companies don't have a better system than this, then make them use this method, but it's ridiculous to make companies give greater prominance to such a flawed methodology than to a far more sophisticated and accurate method using 3d modelling for shading impact, and PVGIS for highly accurate localised sunlight and temperature data.

It also severely penalises those using more efficient inverter set ups as it makes no allowance for this at all that I can see, yet there can be a 5% performance advantage between an old style inverter and the latest high efficiency TL inverters operating at the peak efficiency point. The shading factor also makes no allowances for inverters with shading functions, or micro inverters, or system designs with dual trackers and correctly orinetated panels to minimise the shading impact, it's just a one size fits all package that means all companies will have to estimate the same output from all system designs, which will put more costly but better performing systems at a distinct disadvantage.

TBH I'm pretty well minded to tell them that we're going to refuse to comply with this guidance as we don't think companies should be penalised for using better equipment, better system designs, and much more accurate methods of producing performance estimates. Let's see them make that one stick in court if they dared to take it that far.
 
Looks like the Kk value for projected yields (per postcode zone) have already been multiplied by 0.8. There are some "handy" disclaimers that the Guide recommends to be used when presenting your proposals to end-clients, but it's clear that what these techniques will effectively do is to remove any differentiators between panels/inverters from one manufacturer and another. Should you decide to also provide additional analytical information to your end-client, the provision of the below statement seems to be required:

3.7.9 Additional Estimates
Additional estimates may be provided using an alternative methodology, including proprietary
software packages, but any such estimates must clearly describe and justify the approach taken
and factors used and must not be given greater prominence than the standard MCS estimate. In
addition, it must be accompanied by a warning stating that it should be treated with caution if it is
significantly greater than the result given by the standard method.
 
Anyone need one of these?......
Sun-Path_Tool.jpg
 
I'd quite like the bubble putting back into one of them we've got, as the bubble escaped somewhere which makes it a bit hard to know if it's level or not.
 

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