Economics and Uses of vertical solar panels in northern latitudes.

[Ripple4]

I wanted to share my most recent project, which was placing solar panels on the exposed parts of the vertical south face of my house. The reason this might be counterintuitive is that it seemed to violate common sense for me because solar panels are not exactly cheap, and it seems reasonable to place the panels in a position that is collecting the most possible sunlight so to maximize the financial benefit. However, after studying this and also doing it, I found a unexpected result. It turns out mounting solar panels on the vertical south face of my home are actually a better return on investment than any other way to mount them. My vertical panels have a 30 year lifetime cost per kilowatt hour of about 3.3 cents/kWh whereas my 22 degree slope ground mount was 4.1 cents per kilowatt hour. This is my costs from tallied receipts accounting for the 2021 26% solar tax credit, reproduction costs might be higher or lower. Of course, I'm assuming that they will last the 30 years, and will have a proportionally transferable value to anyone who buys the house after me.

This is exciting I think because the mental image that may pop into a persons head when they hear home solar panels is a large ground hogging array or roof installation. also the other benefits include not getting wintertime snow build up on them, which helps with the main benefit of a vertical south facing solar panels which is that they have the same, or even more power output in winter than summer, which is great because this production profile may line up with energy use better than a traditionally 4/12 or 20 degree sloped roof.



This population chart shows that most people in the USA live north of the 37th parallel (roughly the Tennessee/Kentucky or Utah/Arizona border), which happens to be about where vertical solar panels begin to have a performance advantage over a ~20 degree sloped ones. The ROI is tricky to calculate however, because more solar panels are needed in a vertical array, and also they will make less total energy. so what this is really about is why vertical solar panels are less expensive to install than sloped on a roof or a ground mount structure. Its the racking and also the downstream forced choices. So a vertical solar panels basically can use much cheaper racking than roof/pole mounted ones, because the wall is already there, the expensive part is already paid for. just a few hanger bolts and some hardware store aluminum angle, and its up. The cost per watt for ironridge brand racking is roughly $50 per panel whereas vertical wall mounting the way I did it cost is $15 per panel.

Here is an image of my house with 10x 100w solar panels mounted up there. There is painted PVC wire protector below the windows and the peak array voltage/current is about 85 VDC/12 Amps DC in 2 parallel 5 series arrangement. In my case I was not even worried that the gutter and eave was shading the top few cells of the solar panels in the summer, since late may I've only gotten 1kWh per 1kWp but in the spring I was getting 5kWh/kWp so this is really just about winter production for me.



the next thing that I'm working on, but is not yet done is installing a minisplit heat pump. I know these get a lot of attention here and on other places, so all that I will add is that if I calculate the cost to run the 19 SEER pump in mild-cool weather at the 3.3 cents/kWh I get a heating cost of $.27 per 100K BTU, where as my existing gas furnace has a cost of $0.42 per 100K BTU. So when this south facing array is getting fall and spring sun, I'm heating with the minisplit and on paper should be at a 40% cost savings over NG.



The location I chose to put the indoor unit is in the space above the stairs going second floor. So with the maximum 25' line set and 16' vertical distance limit, I had to put the outdoor unit on my front porch. Since that was not good aesthetically, I covered with with a decorative railing. there is even enough space for the colorful chair to fit. Its like its not even there! also air source heat pumps get a $300 2021 tax credit!

I would like to paint these plastic decorative railings banana yellow to match the chairs. Other people think tan to match the siding,  Thoughts?

here is a video that explains the off-grid vertical solar panel idea: https://www.youtube.com/watch?v=LdqaPbrNYrQ

[nereo]

P2F

Our latitudes in the US are fairly benign compared where most people live in Europe. I have friends in northern Germany (which is further north than Calgary, Canada) who have some vertically oriented PVs and have noted that on sunny days with snow on the ground they can peak out pretty easily. With the shorter day lengths in winter it doesn't last long, but you can still generate some impressive kw*hs

[uniwelder]

I’m going to check production estimates on pvwatts when I get home later to verify, but your post is interesting. I don’t understand your $ numbers regarding ROI. If you save $35 per panel with diy racking, what is your overall cost per panel installed?  I would have guessed about $300 or so. You’re saving maybe 10% with what I would have thought would be much less output than that.

Are you grid tied? If stand alone, maybe that’s why you only care about winter production.

Also, if this is diy, what’s keeping you from making your own racking for a roof mount system?

If you like yellow, go for it!

edited to add---  I reread your post and realized you have 100 watt panels mounted on the wall.  I had assumed they'd be 300 watts or so originally.  Did you happen to get them super cheap or are they much smaller in size to reduce shadowing from the roof overhang?  It seems even more difficult to justify ROI with such little output, unless they were very cheap.

[uniwelder]

I just looked at PVWatts and for Toledo, Ohio, there doesn't seem to be any difference (calculation came out within 1%) in 6 months of winter production, October-March, whether you have the panels mounted on a roof or vertically.  There was a steadier output for the vertical panels during that timeframe, but also 70% less output overall when looked at annually.

Sorry @Ripple4 but you'll have to lay out your numbers a bit more clearly so I can understand your logic.

[Ripple4]

This is a fair challenge, thanks.

on the first post I guess naming that racking brand might have been confusing, that was intended only to show the one part of the lower price, which is the racking. But that would only have been relevant comparing vertical solar panels to a shingle roof mount, which I am not very knowledgeable about. The statement I made that vertical solar panels are the best deal was comparing vertical solar panels put on an existing building to a new fixed pole mount array that is angled.

Anyway, The analysis on the pvwatts website I did was based on a constant energy yield and retail prices, so I compared 8x 100w solar panels in the 20 degree sloped array and compared to 12x 100w panels in the vertical array. Both scenarios had 1000 kWh annual yield at 41.5n. The assumptions that I used compared a ground pole mount ($400) for the 8 sloped panels, and wall mounting for the 12 vertical panels ($60). Both scenarios include a $650 lithium battery of the same size. And $.50/W for the bare solar panels. this ends up at an installed cost of $1710 for the sloped array and $1570 for the vertical array, both making 1000kWh/year.  Assume they both last 30 years and the install is this year (26% pv credit) and you have got $.057/kWh (fixed slope) vs $.052kWh (vertical). This $140 price difference in the installed cost ends up being 5 tenths of cent per kilowatt less for the vertical array over the lifetime, not much but still less. In my specific installation I only had the 10x 100w panels (only ~900kWh per year) and my out the door installed total was $910, but I already have the battery.

Question, what are realistic DIY and pro costs for a shingle residential roof and grid tie? This is the most common type of residential solar up to this point. The tesla roof is not really an honest scenario since it cost high five digits, and on the other extreme a harbor freight kit screwed to a shed roof in the yard won’t last 30 years, nor will anything with flexible in the name. I see roof/grid-tie DIY ‘kits’ in the ~$2.25/kWp range before tax credit, is this fair?

Nereo, Thanks for sharing that info about Germany, There is very little information about vertical solar panels, I only saw a few videos and articles from Europe. Even in the US there is maybe 20 articles and 10 videos.

[uniwelder]

OP, I read through your history of posts and came across your youtube video---https://www.youtube.com/watch?v=LdqaPbrNYrQ  Its great!  I don't know why you didn't include that in your original posting.  Reading through also answered a bunch of my questions--- you have an off grid system, got your panels used/cheap, and seem to have all this very well planned.

I don't have solar panels on my house yet.  A friend of mine has a solar installation company and I think $3/watt is about the going installed cost of a grid-tie system on a shingle roof.  I planned on DIY for my system and do my own racking, but my roof is metal--- the ribbed screw down type of panels.  I figured on using 1.5" square aluminum tubing, mounting 3" long pieces through the flats to the trusses, then 20' long pieces across those for mounting the panels.

[Ripple4]

This is a good suggestion, I'll put a link to the video in the first post to save other people the hassle. thanks!

While this post and topic are all about new equipment that anyone can buy on amazon and typical home store, Its true that I used second hand solar panels for my other array. If I could do it over that would not have been the optimal choice for longevity. The Canadian solar bifacial 144 half cut cells ones (CS3W-395PB-AG) are really interesting. If I repaneled with these I could really boost output and still beable offload the good used ones for what I paid two years ago.

I'm not sure what the map looks like going forward for grid-tie, at face value reducing consumption is like NOT buying power at 10-20 cents per kilowatt hour, but with the trend of imposing fixed grid-services fees and the different rates for outgoing and incoming power, I'm not sure I understand what the value proposition is on this moving forward. I know that lots of people have old legacy net-metered power plans with the same rate in as out, but that's being changed all over the county right now to the asymmetric rates (full-cost for consumed power and the generation rate or less for exported power.)