New MCS MIS3002 and PV Guide

[jerriais]

other than the hand held tool - were do you buy a sun path diagramm to draw on?

You can get the appropriate one (accurate to one degree of latitude) here Sunpath Diagrams

 

[Earthstore]

other than the hand held tool

Bet that raises some eyebrows on surveys..

 

[Berneray]

This is mannah from heaven for the shiny suit guys.....because the figures before shading are better than before. And they will completely ignore any shading factor.

On a side issue......do you know an eight panel 2kwp system with micro inverters will outperform a 4kpw system without. How do I know that. Because a shiny suit rep from a large national company told a couple in Fife that earlier in the week. And the cost. Only £9500.

And he also told them the annual figures were quarterly. And that this system would earn more than enough to cover the monthly payments of £185 and leave enough over to pay their electric.

Are guys like that going to even bother about shading....

And how can MCS or REA police what they show and tell.

 

[Berneray]

For a small company...(just the two of us) I think we install a relative high amount of SolarEdge especially on properties where shading is a factor.

Will there ever come a time when the benefit from the additional cost of SE can be factored into a SAP calc.

With these new guidelines where shading take a more prominent role than before it seems wrong that a calc for a standard install on a roof with a dormer will come out the same as for one using SE.

Because when consumers as comparing quotes the payback time for an instal with SE will seem longer than one without. Of course its my job to explain the benefits....but how often do we all loose jobs simply because people often times opt for the cheapest or easier to understand option...

 

[TedM]

Microinverters and systems capped by inverter size seem to be completely missing from the new calcs.

 

[The Solar King]

I have been scratching my head over these irradiance tables. I thought they were based on the methodology set out in the draft of SAP2012 which uses the same regions. I can get no consistent reconciliation between the two. The draft of SAP2012 still uses the 0.8 multiple. Applying this to the irradiance figure calculated from the methodology gives a range of results for differing zones in the UK which do not equate to the figures given in the PV guide. I have compared the figures to PVSol and SAFPVGIS as well.

A couple of examples:
All are for a south facing roof at 40deg inclination.
Zone 17 (Scottish Highlands) SAP2012: 968kWhrs x 0.8 = 774 kWhrs, PV Guide: 837kWhrs, PVsol:809kWhrs, SAFPVGIS: 794kWhrs
Zone 15 (East of Scotland) SAP2012: 993kWhrs X 0.8 = 794.4kWhrs, PV Guide: 944kWhs, PVSol 849kWhrs, SAFPVGIS: 890kWhrs
Zone 12 (Cambridge) SAP2012: 1153kWhrs x 0.8 = 922 kWhrs, PV Guide: 962kWhrs, PVsol 892kWhrs, SAFPVGIS: 971kWhrs
Zone 1 (Croydon) SAP2012: 1140kWhrs x 0.8 = 912kWhrs, PV Guide: 985kWhrs, PVSol:882kWhrs, SAFPVGIS:947kWhrs

It would be useful to know what methodolgy as been used to create the datasets given for each region in the PV Guide.

Confused? You should be

 

[Gavin A]

from those figures I'd suspect it uses x 0.85, and slightly different starting data than SAP2012 - maybe it incorporates a couple more years insolation data or something.

 

[dansk]

Micro inverters are included if you can be bothered. it states a shade calculation can be done for each independent MPP, twin trackers can have two shade calcs and therefore Solaredge also if you really wanted to do one for each panel.

 

[TedM]

Thanks, I'd missed that. Will have to re-read that section.

 

[Gavin A]

Micro inverters are included if you can be bothered. it states a shade calculation can be done for each independent MPP, twin trackers can have two shade calcs and therefore Solaredge also if you really wanted to do one for each panel.

I suspected that'd be how they'd do it, but seriously 16 x shading calcs for a microinverter system, when each calcs only gives an accuracy of +/-10% anyway is nuts.

I don't actually mind that they're giving this as a methodology for people to use who haven't got a better methodology, what I object to is their insistence that everyone must use this method even if they also use a much more accurate method, and that the more accurate method can't be given greater prominence than the inaccurate method they've devised.

Even this method though makes no allowance for the use of systems like the optitrac global peak function that's avaialble on later generation SMA & Power-One inverters that when combined with correctly orientated panels enable the bypass diades in the panels to be used to massively reduce the impact of hard shading compared to an inverter without a similar feature.

We produce 3d models for every system we install, then assess the shading and specifically design the system to minimise that shading impact when combined with the global peak function, yet we'll have to be giving the exact same output predictions as some clown outfit that just wacks the panels on the wrong way round, and uses the cheapest inverter without a global peak type function on it. All this does is to reward the installers of cheap rubbish and penalise those who take the time to design and specify each system correctly to maximise the generation potential from that site. This is entirely the opposite of what MCS should be trying to do - they should be aiming to raise standards not lower them.

 

[The Solar King]

From my experience PVSol is not the greatest with micro inverters either. There are times when it shows no gain or even a lesser output than a conventional inverter when this should clearly not be the case. I have even dis-assembled a micro inverter array in the software making it individual panels on different parts of the roof. The sum of the individual panels comes out the same as the array, which is clearly incorrect. It seems the software cannot show the advantages of micro inverters where there are shading issues.

Having said that, the shading model in PVSol is excellent for general use. The 3D animation allows you to look at panel placement to optimise output, and also the effect of cutting the tops off conifers to lessen the impact!

 

[SolarCity]

I agree SK. PV Sol does seem to struggle with micro inverters and I can't really work out why - or if there is something that I'm missing.

 

[The Solar King]

I suspect PVSol is falling behind a little and not keeping up with technological advances. It was only in the last update that it became possible to do an East-West arrray. I didn't buy that update as I feel it is a bit cheeky to be asking one to pay for things the software should do anyway. Dr Valintine and the Solar Design Company will need to pull something pretty spectacular out of the bag to persuade me to part with yet more money at a time when prices for equipment and the amount one gets for a job are falling.

 

[SolarCity]

The way that PV Sol deals with split arrays - and for different strings on different MPPTs with different shading issues - seems to be spot on, so I don't see why it should be any different with the micro inverters. Surely it is effectively the same thing?