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**J.P.M.** · 06-18-2015, 04:44 PM

Originally posted by mungosocal

Hi folks, I just introduced myself over in the intro area, but I'll repeat all that below and then ask some particular questions. Once I get my post count up to ten I hope to ask some of you locals for referrals to the contractors you went with and get some meetings set up where I can learn more about my unique situation.

I'm a homeowner in Poway, CA (near San Diego) that had for a long time dismissed solar power for our home for a few reasons (oldish roof, relatively low consumption, etc.) but am reconsidering. So I'm going to poke around the forums and see what I can learn. New developments for me is that I've realized that I could install on a patio cover of which we have several (and were already thinking of expanding), and that my consideration of an electric vehicle would significantly increase our electrical consumption and change the ROI on a solar system. Present consumption is around 500 kwh in the non-summer months with the hot months distributed from 600-1150 kwh. My newbish initial thinking is that something smallish like a 2-3 kw system would serve my needs best, particularly since I don't have unlimited square footage.

What should I be thinking about when considering panel placement on a patio cover? Current assumptions are that patio covers adjacent / connected to the house are going to be a lot easier to install than free-standing structures which would involve a lot of exposed electrical and need for trenching over a paver patio. Agree or is that a non-factor? Also, traditional painted wood patio covers don't last forever. Should I be thinking of composite or aluminum for any new structures that we may add to increase our panel potential? Or does painted wood structure generally share a lifespan with today's panels? I know (at least most of you) are not accountants, but would a new structure built to host a solar panel be a reasonable cost to claim the tax credit against?

Thanks for helping me work through this. I've got a lot to learn . . .

See other post.

But add: Horizontal placement may not be a good idea. Production will be from the lower than tilted from the start and fouling (dirt) will be a bigger problem than if the panels are tilted.

**mungosocal** · 06-18-2015, 05:33 PM

Originally posted by J.P.M.

See other post.

I saw the replies over there and thank you for that. I was surprised that you were recommending such a large system (5 kW + more for an EV) for what I thought were relatively modest consumption numbers and overall goals, but I suppose that will make more sense once I learn more.

**easye** · 06-18-2015, 07:18 PM

Originally posted by mungosocal

I saw the replies over there and thank you for that. I was surprised that you were recommending such a large system (5 kW + more for an EV) for what I thought were relatively modest consumption numbers and overall goals, but I suppose that will make more sense once I learn more.

the deal is, if you are going to get a system then get a system. Your consumption really isn't that low and falls in line with a lot of members here. Bottom line is a solar system provided you stay in the house for 8 plus years will almost certainly save you money. My understanding is once you take the credit you are done. Adding on to a system can be very expensive since initial labor is spread out and inverters are used based on system size. If you are sure you are getting an EV, it shouldn't be too hard to estimate the usage and size the system accordingly.

**DanKegel** · 06-18-2015, 07:29 PM

Originally posted by mungosocal

What should I be thinking about when considering panel placement on a patio cover?

+1 to everything JPM said.

Are these patio covers supposed to keep rain out, too?
Unless you've got a very special look in mind, you'll probably want to tilt mount
the panels to catch the sun better, but that might complicate keeping rain out.

If the backs of the panels will get lots of indirect light, you might consider bifacial panels.
As JPM will tell you, they're newfangled and unproven, but you might get a 10% boost from that back lighting.
(I'm about to try out a couple GxB300 bifacial panels next to a bunch of LG305's, but I have no idea how well they'll work in practice.)

**mungosocal** · 06-18-2015, 07:46 PM

The existing covers are not weatherproof, but there just to cut the sun a bit and make it more comfortable underneath. I mentioned expanding my covered areas but would first like to see if simply paneling my current covers would present a viable option. I am not sure my limited range of options available to me right now (I am not comfortable with exploiting my current roof nor do I want to buy a new roof right now) warrants gathering more than a basic understanding of the technology, like it would it I had to evaluate a full spectrum of options. Knowledge never hurts, but if it isn't going to work for me given my existing constraints I hope to get to that answer quickly. Perhaps if I posted a couple of pics of the candidate locations and dimensions you could help me determine if they are worth pursuing (and committing to forging a solar link on my maester's chain). Apologies for the game of thrones reference...I am in withdrawal.

**mungosocal** · 06-18-2015, 08:07 PM

mungo house.jpg

This is the view looking east.

On the back of my house (west) is the smaller cover that is approximately 8 x 19, minus a couple square feet for the chimney. We had given some thought to expanding the size of that cover along the back of that house, but I'm not quite happy with where the posts would fall so would like the put that thought aside.

On the side of the house (south) is a larger cover that is approximately 9 x 32. It currently has some solar fabric on it in case you're wondering. Clearly there is some potential issue with the roof obstructing the sun under certain conditions, but perhaps some portion of that might be usable.

Seems to me that the small cover area only yields up to 2 kW using the most efficient and expensive panels, and I suspect that wouldn't be a sound investment. Is a portion of the larger patio viable though?

**DanKegel** · 06-18-2015, 08:11 PM

If you lay the panels flat on either of those patio shades, they won't get as much output
as if you tilt them... and tilting them would look kind of ugly.

Tempting to say "wait until you replace your roof".

**J.P.M.** · 06-18-2015, 08:28 PM

Originally posted by DanKegel

+1 to everything JPM said.

Are these patio covers supposed to keep rain out, too?
Unless you've got a very special look in mind, you'll probably want to tilt mount
the panels to catch the sun better, but that might complicate keeping rain out.

If the backs of the panels will get lots of indirect light, you might consider bifacial panels.
As JPM will tell you, they're newfangled and unproven, but you might get a 10% boost from that back lighting.
(I'm about to try out a couple GxB300 bifacial panels next to a bunch of LG305's, but I have no idea how well they'll work in practice.)

To be clear, until I see vetted serious published data I can believe to the contrary, my opinion is that bifacial panels are not worth the hype or expense. I believe, as I stated in prior posts, that under anything like a usual configuration, bifacial panels will boost performance by about 1 % or so. You really need to rig the game to make exaggerated claims have a chance of being close to reality about how great they are - such as single or multiple rear reflectors, or very high tilt angles or other schemes rarely seen in real applications.

IMO, Dan likes to cherry pick published stuff - Often it seems from some source with skin in the game that others may or may not agree with, and claim/imply by innuendo that it's akin to the holy grail of renewable energy.

I've stopped responding to Dan's stuff as I'm of the opinion that it's a waste of my time. I respond here because of what I see as the confusing nature of the sentence with my handle in it that may lead to an inference by readers of the post that I believe a 10 % performance enhancement is possible from bifacial panels. To be clear to the risk of redundancy, I do not. IMO, based on my own prior work both academic and experimental, bifacial panels are a gimmick.

Given some serious published research I can agree with, I may modify or change my opinion, but not because I get why daddy type poorly constructed attempts at Socratic type questioning that are little more than argumentation as an end in itself.

**mungosocal** · 06-18-2015, 08:55 PM

Ugliness doesn't bother me -- nobody would really be looking at it and if they did they would first notice the ugly red shingles.

**DanKegel** · 06-18-2015, 11:00 PM

Originally posted by mungosocal

Ugliness doesn't bother me -- nobody would really be looking at it and if they did they would first notice the ugly red shingles.

Well, ok

So, how many hours of uninterrupted sunlight do each of those patio roofs get?
i.e. how long is it between when the last shadow on the roof goes away in the morning,
and the first shadow appears in the evening?

Also -- I know you said your monthly usage is 500 kWh to 1150 kWh.
How much do you pay for that, and what's the smallest number of kWh
you'd have to knock off to get down to a cheaper price tier?

Finally, have you replaced all your incadenscent bulbs with LEDs yet? I had to ask

You may be able to scratch your itch by efficiency improvements rather than adding solar.

**Living Large** · 06-18-2015, 11:14 PM

Originally posted by J.P.M.

Given some serious published research I can agree with, I may modify or change my opinion, but not because I get why type daddy poorly constructed attempts at Socratic type questioning that are little more than argumentation as an end in itself.

Whoa, daddy, that is the most profound and confusing sentence I've seen here, or most anywhere.

**J.P.M.** · 06-18-2015, 11:22 PM

Originally posted by Living Large

Whoa, daddy, that is the most profound and confusing sentence I've seen here, or most anywhere.

Take what you want of the post that profundity came from, but not out of context. Scrap the rest or use as your needs dictate.

Respectfully,

**J.P.M.** · 06-19-2015, 12:01 AM

Originally posted by Living Large

Whoa, daddy, that is the most profound and confusing sentence I've seen here, or most anywhere.

edit: Change "why type daddy" to "why daddy type".

My error. Brain flatulence.

**thejq** · 06-19-2015, 02:24 AM

Originally posted by mungosocal

Ugliness doesn't bother me -- nobody would really be looking at it and if they did they would first notice the ugly red shingles.

I'm not sure why you'd think aesthetics is not a big deal. If you're spending that much money to build a patio cover and install solar, making it look nice is as important as other aspects. After-all it's part of your house. If you don't like the color of your roof, is it old enough that you want to change it in the near future? If so, doing it now with your solar will allow you to claim more tax credits. Personally I think installing solar on patio cover is not a good idea. Because of the height and load (and wind) bearing, you probably also need permit to build the patio cover which is not going to be cheap. Have you talked to any reputable installer to see if they can give you any advice WRT your idea?

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