New SAP an i doing this right?

[saint]

Am i doing this right? Seems like a lot of kWh's compared to the old way....

3kWp, SW facing, 45 degree pitch, no shading, zone 2.
3x1049x1=3147kWh.

The old way.
2393kWh

i know the old way under cooked it but........

 

[Somecamel]

Yep that's right- The old SAP automatically took off 20% to account for a small amount of shading and irradiance loss, the new calc adds this back but we must be really careful with the shading and not under estimate it- You played around with this yet?

http://easy-pv.co.uk/performance.php

 

[SRE]

Just tried it - great concept but doesn't provide a figure. I'll have to drop them an email - must be my postcode area. Hopelessly inaccurate way of measuring shade unless you're in the middle of where the array is going though.

 

[confounded]

Worked for my area if you call predicting 4364 for a 4kWp system with no shading on a south facing roof as working. We would have oversold every single system we have installed if we had been using these figures. We use PV SOL and find it to be an excellent prediction including cases where shading is modeled in.

 

[saint]

Worked for my area if you call predicting 4364 for a 4kWp system with no shading on a south facing roof as working. We would have oversold every single system we have installed if we had been using these figures. We use PV SOL and find it to be an excellent prediction including cases where shading is modeled in.

But you have to use these new figures don't you? So what are you doing to avoid over selling?
I believe the new SAP over estimates and may cause a real problem for our industry. I'm guessing around May 2014.

I raise this point because i have been asked by a customer how confident we are that the system we have designed will achieve the estimated yield figures.

I would love to hear others opinions on this.