diy solar

diy solar

I don't like adjustable racking

740GLE said:
What about those fancy auto tracking systems? Must be able to pay back the extra cost in a couple months for the extra output right?

Lol

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I went to JRC and selected my location. Used 10Kw of PV.

Difference was 38% for dual axis tracking compared to fixed 47 degrees.
 
I've been looking at possible locations here if I want to add more PV to get faster SOC recovery on the battery bank or generate more electricity for heat pumps.

I'm thinking vertical on my storage shed south wall above the overhead doors. Shed is 60 feet wide. Landscape pattern. I don't need more PV in summer.
 
Zwy said:
I've been looking at possible locations here if I want to add more PV to get faster SOC recovery on the battery bank or generate more electricity for heat pumps.

I'm thinking vertical on my storage shed south wall above the overhead doors. Shed is 60 feet wide. Landscape pattern. I don't need more PV in summer.
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I'm also considering vertical arrays.
I need more winter production. Summer is covered by a mile.
 
Zwy said:
The problem here is if I get snow on the panels and it takes 2 days while the sun is shining to melt it off, followed by 4 days of fog/clouds, the battery bank will be depleted. Not an unusual occurrence and if windy it takes more battery. If I had those 2 days of lost production instead, going the next 4 would be easy.

During days the sun dogs are out, it is -20F for possibly weeks. Sun shines but if I had a fixed angle array, it would be covered in snow that whole time because the panel surface won't get warm. Last year I ran a test, left panels at 47 degrees when it snowed, let 3 inches stick on it, then tilted to 65 degrees the first sunny day. It took 2 days to get the snow off, the snow would slide down to the silver frame and refreeze due to the cold temps. Any snow after that and what little snow stuck to the panels; if it started snowing while the sun had warmed up the panels. was gone before noon the next day.

That told me I made the right decision for this area. Fixed mounts work in some areas, move north with snow and you would think much differently.

One thing I always wondered is if the calculators on PV Watts and JRC Photovoltaic (my preferred) are based upon historical data for cloudy days or the sun coming up everyday and shining? My guess is the calculators are based upon real historical data using PV panels. The big question with using one of these calculators is whether any snow was on the panels and how long before it was cleared off?
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Nah you do a fixed array at 65 degrees. In summer it isn't ideal but you have so many more sun hours it probably doesn't matter. If you build for winter you're set for all year anyway!
 
I'd be tempted to stick some heat tape to the backsides of the panels. Not sure how much it would help or how many precious watts it would take though. Hopefully take less than the lost watts from snow coverage.

I'm not getting up on my 2 story roof to try this though.
 
yabert said:
No. I thought the same and I regret.
I now think about vertical array or at least 75-80°.
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It will be a ground mount.
I can clear it myself if needed. I was just hoping that I wouldn't have to. Not changing the angle from optimal.
 
SparkyJJO said:
Nah you do a fixed array at 65 degrees. In summer it isn't ideal but you have so many more sun hours it probably doesn't matter. If you build for winter you're set for all year anyway!
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Not the way I air condition my house. Meat locker cold. :ROFLMAO:

35% less in July when comparing 30 degrees to 65 degrees.
 
Regarding that 35% loss of potential yield for July when comparing 30 to 65 degrees, yes, I know some of you will say it will still be plenty.

My idea is always to find a use for excess.
 
Zwy said:
The problem here is if I get snow on the panels and it takes 2 days while the sun is shining to melt it off, followed by 4 days of fog/clouds, the battery bank will be depleted. Not an unusual occurrence and if windy it takes more battery. If I had those 2 days of lost production instead, going the next 4 would be easy.

During days the sun dogs are out, it is -20F for possibly weeks. Sun shines but if I had a fixed angle array, it would be covered in snow that whole time because the panel surface won't get warm. Last year I ran a test, left panels at 47 degrees when it snowed, let 3 inches stick on it, then tilted to 65 degrees the first sunny day. It took 2 days to get the snow off, the snow would slide down to the silver frame and refreeze due to the cold temps. Any snow after that and what little snow stuck to the panels; if it started snowing while the sun had warmed up the panels. was gone before noon the next day.

That told me I made the right decision for this area. Fixed mounts work in some areas, move north with snow and you would think much differently.

One thing I always wondered is if the calculators on PV Watts and JRC Photovoltaic (my preferred) are based upon historical data for cloudy days or the sun coming up everyday and shining? My guess is the calculators are based upon real historical data using PV panels. The big question with using one of these calculators is whether any snow was on the panels and how long before it was cleared off?
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This is so-far out for me it's tough to fathom. Is snow that white ice stuff?

So when I lived where that sh*t fell I used to have to shovel the walk. White sh*t used to slide off the roof on my freshly shoveled walk from time to time. Now if you mounted the panels to the roof I would think you really only need to get the bulk stuff off, the sun and reflected heat should melt or sublimate any small amount. Thus I would probably engineer a simple squeegee type device that would pull the bulk of the snow down. I would think the farther north you go the better your result if you tilt for the seasons, but I can tell you here in Phoenix you would be totally wasting your money trying to do any 'tracking'. I'm not sure you could get 5% more total output much less 10. A simple tilt adjustment in the spring/fall for winter/summer angles may net you 3-5% but playing with laying loose 250W CS panels in my back yard propped on cinder block I'm not seeing much difference. I'm building a small ground mount, trying to figure out where to face it.

Facing panels dead west at the setting sun the production curve is about 1/2 hour to an hour different at the extreme edges. But that gap narrows to 15 minutes when production hits in the 20% range, thus any tracking is really only of benefit at the edges where you are not getting much output anyway. YMMV.
 
ksmithaz1 said:
This is so-far out for me it's tough to fathom. Is snow that white ice stuff?

So when I lived where that sh*t fell I used to have to shovel the walk. White sh*t used to slide off the roof on my freshly shoveled walk from time to time. Now if you mounted the panels to the roof I would think you really only need to get the bulk stuff off, the sun and reflected heat should melt or sublimate any small amount.
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Must not have been cold where you lived. My sister lives in Colorado Springs and it snows but all melts in a few days. Here, it might come and not disappear until late March. It won't get warm enough to melt anything.

ksmithaz1 said:
Thus I would probably engineer a simple squeegee type device that would pull the bulk of the snow down.
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That sounds like work. I turn the crank on each pole 10 turns and I'm done for 4 months.

Considering some here claim to be lazy, I'm surprised more haven't figured this out. :)

ksmithaz1 said:
I would think the farther north you go the better your result if you tilt for the seasons, but I can tell you here in Phoenix you would be totally wasting your money trying to do any 'tracking'. I'm not sure you could get 5% more total output much less 10. A simple tilt adjustment in the spring/fall for winter/summer angles may net you 3-5% but playing with laying loose 250W CS panels in my back yard propped on cinder block I'm not seeing much difference. I'm building a small ground mount, trying to figure out where to face it.

Facing panels dead west at the setting sun the production curve is about 1/2 hour to an hour different at the extreme edges. But that gap narrows to 15 minutes when production hits in the 20% range, thus any tracking is really only of benefit at the edges where you are not getting much output anyway. YMMV.
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Here is fixed 45 degrees for Phoenix

Phoenix 45 degrees fixed.jpg
Next is 2 axis tracking

Phoenix tracking.jpg

So what were you saying about tracking won't affect yield much in Phoenix?
 
8.8kw ground mount NAZ PVWatts says:

IMG_0565.jpeg

15, 30, 35, and 45 degrees.
30 and 35 could go either way it seems as far as the best overall annual production fixed which is what we’ve been planning
I also ran numbers for 10, 20, 25, 40, 60, and 90 which was unproductive

If it was a single tilt of 15 in April-September and 45 in October-March it equates to16,583 which does not seem worth the hassle as most months were fairly consistent regardless of tilt.
 
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ksmithaz1 said:
I would think you really only need to get the bulk stuff off, the sun and reflected heat should melt or sublimate any small amount. Thus I would probably engineer a simple squeegee type device that would pull the bulk of the snow down.

Facing panels dead west at the setting sun the production curve is about 1/2 hour to an hour different at the extreme edges. But that gap narrows to 15 minutes when production hits in the 20% range, thus any tracking is really only of benefit at the edges where you are not getting much output anyway. YMMV.
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Both interesting points. My assumption in regards to snow was similar to your statements. There’s a few comments in here that have me second guessing that.
But then one must also consider that @Zwy says he’s got consistent temps of -20F and I simply can’t relate to that. Maybe that’s why it lacks opportunity to melt as that’s simply brutally cold.
I hope I fare better with longest cold stretches being a week of lows around 0 to 5F, otherwise your squeegee idea may come into play.

Your second piece about sunset and only gaining 30min to an hour is a bit surprising to me. I’ve been trying to understand the data of E/W arrays to extend production hours thus reducing battery demand but an hour or less is much different than 2-3. Hmm.
 
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For my area (NH and ME) the snowiest part of the year is we’ll past the winter equinox, typically
February thru late March.

This snowy time of year there are more sunny bright days (still plent cold) than snow days. Also typically the day or two after the Nor Easter, it’s blue bird sky’s and that sun does a number on anything dark. Having a south facing steep paved driveway is a godsend once a little bit of black is showing.
 
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