estimating shading effects

[Don Jeansonne]

I am trying to decide if a solar system makes sense in my situation since I have a significant amount of shade. It seems that I have about 4 hours of full sun on my roof.

A contractor / seller ran a program (SolarPathfinder) to calculate the expected kwh for each month of the year.

My question is does anyone have any experience or knowledge on the accuracy of such programs? I am trying to assess what are my risks in success.

Thanks

[Vic99]

I've had an active system on my roof for less than a month in MA.

I had 3 companies evaluate my set up. One used a digital pathfinder program, the other two took a photo of a dome-like device on my roof. Readings were 79, 80, 81%. I have to say that late Oct, early Nov is more productive than I thought. Part of that might be because leaves are mostly off of the trees and only a few limbs shade. Chimney and a dormer give a little shading at certain times of day as well.

To deal with shading not shutting down the whole array, I went with enphase microinverters. They allow each panel to operate independently. Not good for bigger panels like Sunpower ~327W, but work fine if your panels are in the 240W range. I have 25 Suniva 255W. Plus the microinverters are warrantied for 25 years.

Good luck.

[Naptown]

Is this thermal or PV, and did they show you the report with the trace and layout?

[Naptown]

I've had an active system on my roof for less than a month in MA.

I had 3 companies evaluate my set up. One used a digital pathfinder program, the other two took a photo of a dome-like device on my roof. Readings were 79, 80, 81%. I have to say that late Oct, early Nov is more productive than I thought. Part of that might be because leaves are mostly off of the trees and only a few limbs shade. Chimney and a dormer give a little shading at certain times of day as well.

To deal with shading not shutting down the whole array, I went with enphase microinverters. They allow each panel to operate independently. Not good for bigger panels like Sunpower ~327W, but work fine if your panels are in the 240W range. I have 25 Suniva 255W. Plus the microinverters are warrantied for 25 years.

Good luck.

the digital one was most likely a Sometric Eye designed specifically for PV
the Dome that they took a picture of is the Pathfinder. '
I have both and use both. the pathfinder mostly for Thermal where deciduous trees can be accounted for, however this is a subjective value.

[Don Jeansonne]

solar shading

Is this thermal or PV, and did they show you the report with the trace and layout?

It is PV not thermal.

The report is only a tabulation estimates for each month's kwh production.It indicated about 60% of an ideal setup.

[Naptown]

It is PV not thermal.

The report is only a tabulation estimates for each month's kwh production.It indicated about 60% of an ideal setup.

that is probably a bit low for a quick ROI And there are other factors such as tilt and azimuth that are taken into account not only shading.
Big question is do the numbers work?

[Don Jeansonne]

numbers are okay for me

that is probably a bit low for a quick ROI And there are other factors such as tilt and azimuth that are taken into account not only shading.
Big question is do the numbers work?

I have special considerations on the net cost to me and other factors so the numbers are marginal but satisfactory.
The report includes tilt and azimuth assumptions.
My problem is that I am trying to assess the risk or uncertainty in the results. If they are conservative then that would be good but if to aggressive then it is bad.

[Naptown]

If the Solmetric eye is the one it is based of of the actual will probably be a bit higher during the winter and spring than estimated if decidious.
Also make sure the image was unedited meaning anything that could shade the array is shown as a green color.

[Greenscape Energy]

Enphase Technology

We have started using the Enphase micro-inverters here in England.
They really perform very well when compared to a standard string inverter in normal situations.
Where there is shadowing across panels, the performance is far superior to any string inverter.
Add in the 25 year warranty and on-line monitoring, along with the extra yield and they are a must have for Solar Installations.

Mod note - Links not allowed.

[bonaire]

It's really hard to know if Enphase will be in business within the 20-25 year window to support the warranty. The 190's were more faulty than 215s are now and needed replacement. They are still a losing-money company (ie. negative EPS).

If you have significant shade - why go solar pv? What about other energy efficiency changes within the house to cut energy usage? Conserve first, solar second - is the rule. If you have done no conservation steps and are looking to do solar, it's not the right way to go. See the sticky link on this forum regarding the conservation angle. http://www.solarpaneltalk.com/showth...-Towards-Solar

Then there is also the more political angle of "why should taxpayers chip in 30% federal and <n> state/local for a system that doesn't perform very well". As we know, the federal program doesn't care if you install the panels in your basement as long as it is installed (a jobs program). Some state programs do a shading review and analyze what productivity the system will have.

[russ]

We have started using the Enphase micro-inverters here in England.
They really perform very well when compared to a standard string inverter in normal situations.
Where there is shadowing across panels, the performance is far superior to any string inverter.
Add in the 25 year warranty and on-line monitoring, along with the extra yield and they are a must have for Solar Installations.

Mod note - Links not allowed.

Trying for free advertising and spreading salesman's BS = shame, shame!