How much Solar energy with only vertically or horizontally mounted solar panels?

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Nov 28, 2019
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I'm curious why you don't think you can tilt your panels. I live in Northern Baja and have my array mounted on a flat roof and tilted @31 degrees. We have strong winds on a regular basis (up to 70 mph) and have even had a degrading hurricane pass over. I have built a cedar dog eared fence type structure to break up any wind that may want to lift my array. It has remained rock solid throughout all wind events. I basically don't even think about it any more.
Thank for for your comment, but am living near the ocean, and some time, only few days a years, the wind is so strong that you
could not walk on top of a flat roof. San Francisco is windy because the ocean is cold and inland areas are hot. When there is any
obstacle, like a mountain, the air traveling from high pressure (cold air) to low pressure (hot air) can go very fast.


Your solar panel would not stand for too long in my area.

ratio3x2_1200.jpg


In my situation, I can only install two panels toward the south,
and when installed verticaly there is not too much difference in winter with a panel installed flat.

The optimum solution that I am considering is to have three sets of six panels each, oriented toward east, west, and flat.
Looking at the numbers previousl generated by @sunshine_eggo, inclining the east and west panels, would be
less efficient in winter, while providing more solar energy in summer than I need to provide ligthing inside a building.

1) 18 panels with 6 flats, 6 vertical east and west:

18 panels - only vertical .jpg

2) 18 panels with 6 flats, 6 east and 6 west with 85 degree inclination:

18 panels - 85 inclined .jpg

3) 18 panels with 6 flats, 6 east and 6 west with 45 degree inclination:

18 panels - 45 inclined .jpg

I am currently considering a battery of 16 cells of 280 Ah, or may be 310 Ah.
I plan to use only 80 % of the capacity of the battery, and I estimate that
I would have overall 20% of losses from conversions, so basically charging
the battery would require about 17.2 kWh of solar energy.

Since I will have some solar surplus, I made a quick study to try
using the extra energy to heat some water or to recharge an EV.

To heat the water I would need an extra water tank and
a 240 V inverter to power one 4.5 kW heating element.

In the case of charging an EV, I could still use a 120 V inverter,
however a 240 V inverter would be more efficient. For illustration pupose,
I estimate a 3 miles range per kWh to include the car AC/DC inverter losses.

In the case of the east and west panels installed verticaly, I will have 12 months of surplus, but
in the case of the east and west panels inclined 85 degrees, I will have only 9 months of surplus, and
in the case of the east and west panels inclined 45 degrees, I will have only 10 months of surplus.

Surplus - Water Heater - EV miles.jpg
 
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littleharbor2

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Ever been in 70 MPH winds? I can relate to your situation as I live on the ocean, (Sea of Cortez) myself. You can't see it from the pic I posted because it is behind me in this picture Sounds like you are already convinced that tilted panels wont work so I'll leave the conversation now. Best of luck in your endeavors.
 
Joined
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Ever been in 70 MPH winds? I can relate to your situation as I live on the ocean, (Sea of Cortez) myself. You can't see it from the pic I posted because it is behind me in this picture Sounds like you are already convinced that tilted panels wont work so I'll leave the conversation now. Best of luck in your endeavors.
Thank you for your comment. To give you a perspective of my project,
I need to get about 18 kWh of solar energy to charge my battery.

Taking as reference my 18 solar panels system (6 flat, 6 east, and 6 west)
I would need to install 12 solar panels with south orientation
and tilted at 60 degree which is the optimum for my location.

As you experienced it in your project, I believe you have 4 solar panels on top of your roof,
building a 12 panels frame construction would be a major endeavour, requiring serious anchoring
on top of the flat roof, and I would prefer not making any holes into the roof. Also when doing the
replacement of the roof cover, it would be a major task to remove and reinstall the solar panels.

There is a cabin on top of the roof where it would be easy to securely bolt the solar panels against the walls.
The south wall of this cabin is not accessible and would require installing some scaffolding otherwise.

I studied multiple combinations of using all together a various number of flat, south, east, east panels,
with different inclinations, and the extra complexity didn't seem worthwhile or cost effective.

See the following summary comparing the 18 panels solution with 12 south panels with various inclinations:

18 panels F E W vs 12 panels south .jpg
 
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littleharbor2

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There are 12 panels on my roof creating a surface of 8 1/2 x 21 feet. Not sure where you came up with your optimum tilt but generally speaking optimum tilt is your latitude. San Francisco is at 37.77 degrees latitude. Try putting that into your calculations and see how your performance is.
 
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There are 12 panels on my roof creating a surface of 8 1/2 x 21 feet. Not sure where you came up with your optimum tilt but generally speaking optimum tilt is your latitude. San Francisco is at 37.77 degrees latitude. Try putting that into your calculations and see how your performance is.
Are you using 12 panels 65" x 39" ? I magine then you put them horizontaly in three rows of four?

I would be interested knowing the different components you are using in your instalation (MPPT, Battery voltage and capacity, DC/AC Inverter...)?

How much power your solar panels were rated and how much power do you effectively get into your battery and provided to you load?
 

littleharbor2

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Older 32" x 64" 180 watt. Landscape orientation, 4 rows of 3.
I only require about 5kwh a day Being that I don't require more power the system throttles back into float for much of the day. My off grid system could create much more power if grid tied.
Older Trace SW 4024, Midnite Solar Classic 200 CC, 550 amp hour @24 volts. AGM battery bank
 

RaySE

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To not open a new topic for every question, I'll just hop along on this one for the moment.

I was trying to find some info on how to mount a solar panel and stumbled on this...

How much Solar energy with only vertically or horizontally mounted solar panels?

Does this tittle actually mean that I can mount the panels vertically or horizontally ?
Does that not give differences in output ? I can respect the incline in both ways.

But I rather have 39 inches up and 64 wide then vice versa. Keeps it all lower to fight the wind.

Thanks for any input,
 

Hedges

I See Electromagnetic Fields!
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"Portrait" vs. "Landscape" doesn't matter, except to the extent of which way shadows encroach and how the panel's cells and diode bypass are laid out.

"Vertical" (facing straight up at the sky) and "Horizontal" (facing the horizon) of course make a difference. Or whatever inclination in between, and orientation East, South, West.

edit: (or maybe "Vertical" is facing the horizon and "horizontal" is facing the sky. I think this would be the vernacular, reflecting angle of a flat panel, not which direction it is facing.)
 
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12VoltInstalls

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Does this tittle actually mean that I can mount the panels vertically or horizontally ?
Does that not give differences in output ? I can respect the incline in both ways.
Re: Hedges said it well

Here’s a lot more than you wanted to know:

If you are not in a snow/ice zone what I do isn’t applicable to you. I have two 400W arrays mounted vertically because I basically never have to get rid of snow this way. 800W total, 4S2P, one SE one SSW. I do not get maximum output but the fuss of snow stopping production of watts - since I can’t be here while at work etc. - is worth the ‘hit’ of reduced production.

One array is installed with the long side horizontal and the other has the long side vertical. No measurable difference other than they are of two brands with slightly different specs so one string potentially could be ‘weighted’ a few percent lower; but maybe not.
When sun hits both panel arrays equally I’ve seen as high as 94V panel output for both strings with only tenths of amps difference between. And it could be either one that’s higher.

In summer 400W makes more than I usually need for fridge, lights, coffee, water, phone charger, etc., most days while on cloudy summer days I often still get charged sufficiently for overnights with the higher VOC strings.

Other than that ‘respecting the incline’ as you say will give you best production.

FWIW department: at my latitude flat-mounted panels appear to lose a lot of watts. Vertical seems to be produce many more watts at the same time and place under clear skies. I’ve experimented with that. I suppose in mid July I theoretically (or likely!) miss a higher percentage of watts staying at vertical, though overall vertical does well for me because I far exceed my needs 28/30 days.
Probably would be quite the opposite in FL, AZ, or Costa Rica…
But I rather have 39 inches up and 64 wide then vice versa. Keeps it all lower to fight the wind.
Other than leverage angle- or perhaps distance from the ground- the square footage presented to the wind will have the identical psf at a given wind speed for all practical purposes.
 

RaySE

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Other than leverage angle- or perhaps distance from the ground- the square footage presented to the wind will have the identical psf at a given wind speed for all practical purposes.
Yes square footage of the panel stays the same, always. But in my experience winds like to "catch" the things that are higher up more easily. And boy we can have some wind here too. So if I can save 25 inch of height without losing any Watts I wouldn't mind.

Thanks again guys.
 

Hedges

I See Electromagnetic Fields!
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It may be that gaps between panels would help spill wind. More significant if they have long sides adjacent.
Wind breaks that are far enough and low enough to avoid shading could help too.

Large engineered arrays can be designed to withstand 100 mph or higher wind (but not debris) by having some diagonal bracing.

I've read that for rooftop, with uplift is a concern, being back from edge of the roof helps.

If you have groundmounts, you have to consider backside wind which is pulling up against whatever clamps, different ultimate strength vs. front side pushing panels against rails.
 

littleharbor2

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I built a cedar dog-eared fence to help minimize uplift. Being that this array is bolted to the roof as opposed to anchored in concrete I felt it was mandatory to do this. Been through a dying hurricane and 70 mph straight line winds so far .


IMG_0015.JPG
 

Don B. Cilly

Energetic energy padawan
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Ibiza, Spain
I basically... don't bother :·)
I live at 38° latitude. Get plenty of sun. My roof is 15° tilt. I have the panels cemented to the roof. No wind will get them. In winter, on sunny days, my (LFP, 5KW) batteries are charged by 12-1300 hrs. In summer, I could power all neighbours if I felt so inclined. I have 3 puny panels, €150 each.

I have a fridge and a washing machine, but I'm reasonably energy-conscious, I don't really draw that much. 24V is good enough.

Now, if I used lead-acid, I'd probably worry - a bit, sometimes. I use LFP, I don't.
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