Novice Looking for Advice

[Chris J]

Hi. This is my first posting. I'm considering a MicrFit (Ontario) solar project for my rooftop and I have a concern with some morning shadowing from about mid September until mid April. There is a 60' mature silver maple in another yard about 70' from the southeast corner of my roof. I have created a very detailed Sketchup model of my home and surrounding yards. When I project the model throughout a year cycle, the maple tracks a hazy leafless shadow across approximately 25% of my roof at the eaves from about 8:00 am until 10:15 AM. After mid April it's not a concern and I have absolutely no shadows from then until mid September when the cycle starts again in Sept.

I have been speaking with an installer who has quoted a 39 panel 9.3kw project all with Enphase micro inverters. The installer has presented projected revenue figures from PV Watts for this installation (roof faces south - 170 degrees, 6/12 pitch, Essex County Ontario Canada). I understand that the PV Watts projections are at optimal conditions so is there a way I can loosely estimate the amount of revenue loss I could expect from this shadow over a year? I just want to make sure it's not a project busting obstacle before we proceed. The expect the installer will also do an analysis but I want educate myself before that's presented.

I'll try to post a photo I grabbed from Sketchup but if that doesn't work it's also posted on flickr - http://www.flickr.com/photos/algonqu...er/5584110868/. It shows how the shadow looked this morning (a bit drastic as the model tree has foliage)

Thanks in advance for your input.

Chris

[Chris J]

Try Picture Again

[IMG]Shadow Projections by algonquin paddler, on Flickr[/IMG]

[MarineLiner]

[Naptown]

have your installer go on the roof and shoot multiple sun studies (At least 9 one each corner and three up the middle and one in the middle of each side.
If using a sun eye or pathfinder they should be able to nail the production fairly closely.
If using Enphase you could get higher production than what is predicted. I have on every shading issue I have had as the pathfinder and sun eye don't count for deciduous trees and show them as a solid year round. Although output will be diminished it will not be 0
The shading is actually not as much of an issue as you might at first suspect. Peak sun hours are really between 9 and 3 from solar noon and production does not dramatically pick up until about 10. This is known as the solar window where most production will take place.

[russ]

Hi Chris - Welcome to Solar Panel Talk!

Insist the salesman show you the calculations - not just say it has been done. Rich may be insulted again but there are too many out there that are not like him (without his good intentions).

The money is yours until paid - then you can plan on getting whatever help the individual company wants to give - often no more than they have to without being sued.

Russ

Here is a shade calculator - Never tried it myself but have been told it is good. 1) Shade Calculator http://www.honeybeesolar.com/shade.html

[Mike90250]

Hybrid system.

Part string inverter on the unshaded portion of the roof, and then micro inverters on the shaded portion. To me, that is the best way.

[Naptown]

Hi Chris - Welcome to Solar Panel Talk!

Insist the salesman show you the calculations - not just say it has been done. Rich may be insulted again but there are too many out there that are not like him (without his good intentions).

The money is yours until paid - then you can plan on getting whatever help the individual company wants to give - often no more than they have to without being sued.

Russ

Here is a shade calculator - Never tried it myself but have been told it is good. 1) Shade Calculator http://www.honeybeesolar.com/shade.html

I agree totally with that And make them show you the different studies. I know A pathfinder will allow the tracings to be shown and I know the sun eye has this capability also. Pathfinder allow for multiple tracings and an averaging if you use the assistant software. doing it manually would be a pain. The other thing you will want to see is the derate parameters they used. This is where all the losses are accounted for such as module mismatch, soiling, inverter efficiency, age, power tolerence etc are set for the system. Post it up if you get a chance I'd love to take a look at it.

[Naptown]

Hybrid system.

Part string inverter on the unshaded portion of the roof, and then micro inverters on the shaded portion. To me, that is the best way.

That would work and could be a viable solution. He just needs to make sure the string calculations work out on the big inverter and have no more than 15 modules on the micro's if they are Enphase 190's or 20 on 380's otherwise costs could rise substantially.
Current set up with Enphase would require 3 AC circuits with 190's or 2 circuits with the 380's. There is no cost benefit to the 380's until you get over 20KW as the trunk cables will eat you alive.

[dvhenry]

One more option!

[Mike90250]

I think that's a bad option. I'd consider a ground mount between the trees, south far enough to avoid shade. Shade on your house will reduce the cooling needed.

[silverhorsefarm]

Since your partial shading happens largely during leafless short days of winter, I think your harvest will be pretty close to optimal, particularly if you use micros. Most of your annual harvest will happen b/w April and September anyway. Maybe some judicious pruning, but spare the tree!

[russ]

It was a rather radical solution

[Naptown]

Hi. This is my first posting. I'm considering a MicrFit (Ontario) solar project for my rooftop and I have a concern with some morning shadowing from about mid September until mid April. There is a 60' mature silver maple in another yard about 70' from the southeast corner of my roof. I have created a very detailed Sketchup model of my home and surrounding yards. When I project the model throughout a year cycle, the maple tracks a hazy leafless shadow across approximately 25% of my roof at the eaves from about 8:00 am until 10:15 AM. After mid April it's not a concern and I have absolutely no shadows from then until mid September when the cycle starts again in Sept.

I have been speaking with an installer who has quoted a 39 panel 9.3kw project all with Enphase micro inverters. The installer has presented projected revenue figures from PV Watts for this installation (roof faces south - 170 degrees, 6/12 pitch, Essex County Ontario Canada). I understand that the PV Watts projections are at optimal conditions so is there a way I can loosely estimate the amount of revenue loss I could expect from this shadow over a year? I just want to make sure it's not a project busting obstacle before we proceed. The expect the installer will also do an analysis but I want educate myself before that's presented.

I'll try to post a photo I grabbed from Sketchup but if that doesn't work it's also posted on flickr - http://www.flickr.com/photos/algonqu...er/5584110868/. It shows how the shadow looked this morning (a bit drastic as the model tree has foliage)

Thanks in advance for your input.

Chris

The operative words here are another yard.
racking, trenching etc for a ground mount system will add 20% to the system cost.
September perhaps early October will be the worst months as the trees will still have foliage spring they leaf out most likely in April beyond the shading.
The OP says that the shade is gone by 10AM. This is the very beginning of the daily solar window. We're making a mountain out of a molehill here. He has several choices.
Use one big string inverter and lose maybe 5% annually. Use two smaller string inverters with one set on the shaded area and lose maybe 4% per year or use microinverters and gain 75% annually (Just kidding) lose maybe 3% to shading. There will be some losses due to shading but they will be minimal.

[Chris J]

Thanks for your input!

It's great to get such passionate responses. Naptown summarized things nicely - the trees are not in my yard and there is no room for a ground mount system. I've been able to use all your suggestions during my discussions with installer. He's aware that I will not proceed without a full shade analysis so I can consider the potential drain on the investment. I'm happy with that.

Now as long as my application doesn't get bogged down in this recent controversy! http://canadasolarforum.com/content....olar-investors

I'll update you as we move forward. Thanks again.

Chris

[russ]

Another member, user name Stomp, just got screwed by a bad installation - take a look at his photos http://www.solarpaneltalk.com/showth...2654#post22654

A good installer that wants to do the job 'right' makes all the difference. Most likely they will not be the cheapest.

Russ