How much is shading affecting your production?

[SunDave]

This time of year, shading is near a maximum for most of us in the northern hemisphere. I took some pictures and timestamped figures in solar assistant to see how much shading affects things. This was an interesting experiment since the top two rows, and bottom two rows are identical arrays, hooked to to the same inverter (on their own MPPT). It's a great real world test, but the numbers will not be identical to others since:

1. This is a string array, not microinverters or optimisers
2. Different panels handle shading zones differently
3. Different MPPTs and other equipment will affect shaded production

Still a cool comparison: All losses are bottom two row production VS. top two row production. NOT losses on the whole array which would be roughly 1/2 what is stated.

The loss due to shade does not scale linearly with how much of the lower array is covered. A little shade is a lot of loss. Lucky for me this is an hour before sunset, so the actual losses only total about 1kWh.

 

[rodrick]

I’ve come to the conclusion that this is the best time of year to find places for panels around the property such a dramatic change from summer

I’ve got a group of trees (5-6) that are killing my production that I didn’t think would bother me on my neighbors property luckily I have a great neighbor and he said cut them down power is more important, we are all totally off grid in the area and everybody knows the struggles in the winter

 

[SunDave]

I’ve come to the conclusion that this is the best time of year to find places for panels around the property

That is a great point. Should be a public service announcement this time of year!

luckily I have a great neighbor and he said cut them down power is more important

And that is a great neighbor.

 

[teal95]

I have 2 spruce trees shading 1 string of panels and another spruce shading the ground mount. 2 of the 3 are ~30 years old and probably 40' tall. The third my wife planted when we moved here 12 years ago, but it's still already over 20'. Unfortunately my wife thinks the spruce are sacred so I'm not allowed to cut them.

 

[Crowz]

I have a stand of pine trees that I will be doing away with eventually that are making my winter production numbers suck big time.

Summer is fine.

I'm dealing with it by positioning panels so that as the shadow goes across one set of panels there are others not shaded to make up for the shaded ones. I'm at least lucky to have a large yard to work with for this.

 

[sunsurfer]

I have a couple dozen of small strings. When one gets shaded, it doesn't pull the rest of the panels down. Don't put all your eggs in one basket.

 

[sunsurfer]

I’ve got a group of trees (5-6) that are killing my production that I didn’t think would bother me on my neighbors property luckily I have a great neighbor and he said cut them down power is more important, we are all totally off grid in the area and everybody knows the struggles in the winter

Sounds like an awesome neighbor. If the trees are big, maybe you can mill them some lumber or at least some extra firewood.

 

[rodrick]

Sounds like an awesome neighbor. If the trees are big, maybe you can mill them some lumber or at least some extra firewood.

Yes he is, we do plan on milling the wood he’s got some building to do and the trees are 60-80 ft and 20-24 inch bases nice ponderosa pines and I got about the same amount and size we are taking out also so we will have free power and lumber doesn’t get much better than that

 

[Daddy Tanuki]

my shading in the summer of course is negligible but int he winter with the sun low in the sky the panels of the roof on the shop start making power almost two full hours later than in the summer and stop about an hour earlier all due to shading. not much i can do about it unfortunately. I have another 8 panels i planned on installing on the west facing side of the shop as it would bring in some power later int he day in the winter, but never got a chance to mount them... maybe next year. in the summer these 8 would make almost nothing due to shading from trees on my property but in the winter with no leaves that entire wall gets good sun from 1230-1530.

 

[ccasj]

I find it odd that seemingly a huge point of solar is sustainability, yet it seems every single user here is absolutely giddy at the thought of mowing down a forest in order to get some more production. I get that some users are truly off grid with no backup options, so that makes a bit more sense, but you'd think there'd be some other options instead of just hacking down all the trees that bother you.

 

[bobbyell0w]

I find it odd that seemingly a huge point of solar is sustainability, yet it seems every single user here is absolutely giddy at the thought of mowing down a forest in order to get some more production. I get that some users are truly off grid with no backup options, so that makes a bit more sense, but you'd think there'd be some other options instead of just hacking down all the trees that bother you.

In my municipality, if a tree is removed due to a solar installation, a tree needs to be planted to replace it. I have 100 trees... not sure where I could even plant a new one.

However, any tree can be taken down if dying or you just don't like it. Took 30 trees down for a pool, no problem.

 

[SunDave]

Trees grow back. I know because I have planted over a thousand of them. I figured I have straight license to chop down a few. At this point I'm still at net +900 trees or so to the good. I'm definitely pro-tree, and pro keeping the old ones around, but clearing some for a good reason is not the end of the world.

There are some trees planted at my parents' place over 50ft tall in 35-40 years. Not a bad start.

Prairie needs a place to thrive too. The area in the picture has a few hundred feet of prairie grasses to the south of it. That area is for grass, snow, the geothermal loop field and an open view.

 

[Rmart30]

In my municipality, if a tree is removed due to a solar installation, a tree needs to be planted to replace it. I have 100 trees... not sure where I could even plant a new one.

However, any tree can be taken down if dying or you just don't like it. Took 30 trees down for a pool, no problem.

Dont know what growing zone you are in but if possible could plant dwarf, or semi dwarf fruit trees that would stay under 15 ft tall. Fuyu persimmon trees can be kept to around the 10 ft mark easily.

 

[Grend]

The shadow producing a 43% loss is alarmingly small. Looks like the size of a big leaf! I thought diodes were supposed to reduce the problem?

 

[SunDave]

The shadow producing a 43% loss is alarmingly small. Looks like the size of a big leaf! I thought diodes were supposed to reduce the problem?

It's about 1/2 of one panel. And it is a 43% loss of the bottom two rows of that picture. The top two rows (different array) are not affected.

 

[bobbyell0w]

Dont know what growing zone you are in but if possible could plant dwarf, or semi dwarf fruit trees that would stay under 15 ft tall. Fuyu persimmon trees can be kept to around the 10 ft mark easily.

Good idea. Not even sure they would come by and check.

My property is 200' x 50', then 400' x 300' so there is 'space' but nothing would really grow due to mature trees. All the open space is where my panels and house are located.

 

[Brucey]

I find it odd that seemingly a huge point of solar is sustainability, yet it seems every single user here is absolutely giddy at the thought of mowing down a forest in order to get some more production. I get that some users are truly off grid with no backup options, so that makes a bit more sense, but you'd think there'd be some other options instead of just hacking down all the trees that bother you.

Trees are renewable. Fossil fuel is a finite resource. I also don't like trees close to the house where they could hit it if they come down in a storm.

 

[BerndL]

Trees are the real enemy. They're virtually useless except as a source of firewood, so I'm planning on getting rid of a few acres of woodland. Park it out for sheep.

Unfortunately my morning shade comes mostly from my neighbor's trees, losing me about an hour of production on winter mornings.

 

[Rmart30]

Good idea. Not even sure they would come by and check.

My property is 200' x 50', then 400' x 300' so there is 'space' but nothing would really grow due to mature trees. All the open space is where my panels and house are located.

they might would come back and check once but unless ya have a busybody in the bunch I doubt it would get rechecked ever again.

I might would even plant something evergreen that could be sold off for xmas trees in 4-5 yrs and cut them down, pocket a little cash and then maybe replant if something was said.

 

[rodrick]

I find it odd that seemingly a huge point of solar is sustainability, yet it seems every single user here is absolutely giddy at the thought of mowing down a forest in order to get some more production. I get that some users are truly off grid with no backup options, so that makes a bit more sense, but you'd think there'd be some other options instead of just hacking down all the trees that bother you.

How many trees are cut down to build houses? you have to clear land and need lumber
If done correctly it can be very beneficial by supplying new habitats for wildlife, old growth forests do not contribute much to the wildlife compared to areas that have been logged and replanted
By removing danger or problem trees and replacing them with berry bushes, shrubs or maybe some food plots is far more beneficial to the ecosystem than a couple of trees
Some of us have a big problem with trees my property has between 100-200 trees per acre ( it was Weyerhaeuser forest land originally logged and replanted) so taking out a dozen trees is not a problem hell we can’t even keep up with deadfall’s we use for firewood some end up rotting which is ok it makes more soil
I don’t think anyone here is trying to clear cut acre’s of land for their solar, but you are right about being giddy when I’m getting more solar while eating those fresh raspberries I planted I’m dam giddy

 

[SunDave]

I should say that both arrays (top half is one, bottom half is another) in the pictures above are 7S2P. That plays into the losses as well. The very bottom row being shaded affects both bottom rows of panels.

I will say I have it good by losing about 1% in the worst part of the year. There are so many posts from people this time of year about crap production. It is partly due to shorter days, but mostly due to shading. In fact, my very best days are between January and April. And that is in the northern hemisphere.

January won't average as high as June, but with the cold weather, and the sun being consistently south all day (good angle) it has some of the best single days. A bright day, with some snow reflection and cold is hard to beat.

 

[ccasj]

Trees are renewable. Fossil fuel is a finite resource. I also don't like trees close to the house where they could hit it if they come down in a storm.

Mature trees on small properties in destroyed ecosystems are not a renewable resource. Also the only alternative isn't fossil fuel...

 

[Daddy Tanuki]

How many trees are cut down to build houses? you have to clear land and need lumber
If done correctly it can be very beneficial by supplying new habitats for wildlife, old growth forests do not contribute much to the wildlife compared to areas that have been logged and replanted
By removing danger or problem trees and replacing them with berry bushes, shrubs or maybe some food plots is far more beneficial to the ecosystem than a couple of trees
Some of us have a big problem with trees my property has between 100-200 trees per acre ( it was Weyerhaeuser forest land originally logged and replanted) so taking out a dozen trees is not a problem hell we can’t even keep up with deadfall’s we use for firewood some end up rotting which is ok it makes more soil
I don’t think anyone here is trying to clear cut acre’s of land for their solar, but you are right about being giddy when I’m getting more solar while eating those fresh raspberries I planted I’m dam giddy

He said Raspberries... almost as good as blackberries

 

[Daddy Tanuki]

Mature trees on small properties in destroyed ecosystems are not a renewable resource. Also the only alternative isn't fossil fuel...

so go marry or mate with the trees... and worry about your own carbon footprint.

 

[ccasj]

so go marry or mate with the trees... and worry about your own carbon footprint.

It's a little telling that you get this triggered about discussing environmental impacts. Thankfully the younger generations care about things other than themselves.