How to evaluate health of a new system?

[insaneoctane]

I appreciate the discussion on my account. I was just about at the point of calling my vendor when I made an observation that likely explains what I am seeing...
And jpm has already included this in his likely possibilities...
As we approach winter solstice the sun's path is lower and lower to the horizon. I have tree tops that are now in my panels line of sight of the sun. So time has both allowed the trees to grow and the sun to lower to where I am seeing a noticeable impact to my daily production. The trees are in my neighbors yard, but they are graded to a higher elevation than my lot which exasperates the unfortunate geometry. I know they would be amenable to sharing the fee to trim, if I push for it... but I am not sure I would get my $250 worth of extra production to knowing it will grow back! Tough call if it only impacts 2 or 3 months...

[J.P.M.]

I appreciate the discussion on my account. I was just about at the point of calling my vendor when I made an observation that likely explains what I am seeing...
And jpm has already included this in his likely possibilities...
As we approach winter solstice the sun's path is lower and lower to the horizon. I have tree tops that are now in my panels line of sight of the sun. So time has both allowed the trees to grow and the sun to lower to where I am seeing a noticeable impact to my daily production. The trees are in my neighbors yard, but they are graded to a higher elevation than my lot which exasperates the unfortunate geometry. I know they would be amenable to sharing the fee to trim, if I push for it... but I am not sure I would get my $250 worth of extra production to knowing it will grow back! Tough call if it only impacts 2 or 3 months...

If it was me, I'd keep an eye on daily production at least until about March 1 and beyond and see if an improvement occurs. That will also give a bit of time to figure out if the cost of trimming (on an ongoing basis given the fact that trees grow or die) is worth the estimated cost of production loss incurred by not trimming.

In the mean time, without taking too much of the vendors time, I'd still call, explain the #'s you have and ask for a quick system check. IF something IS amiss, you'll probably find a more sympathetic ear right after startup than several months or longer down the road. Even if the vendor blows you off, you'll be on record as reporting a concern. That can always be of future use if shading turns out to be only a part of the problem. Worst thing that can happen is a call to the vendor won't hurt - unless you get rude and unreasonable.

For potential solar customers reading this: a heads' up - Often, a site survey done before purchase/install w/ a shading tool gives owners a heads' up on likely shading situations. Most reputable vendors have this capability.

Isooctane: No disrespect intended or implied here - FWIW, I would have gone outside and looked at my system at several times on sunny days looking for shading or shadows before assuming system problems. Shadows are pretty easy to spot and are a common cause of reduced production.

In any case, thank you for the follow up and the consideration that goes with it.

Stay dry.

[bcroe]

Shade

As we approach winter solstice the sun's path is lower and lower to the horizon. I have tree tops that are now in my panels line of sight of the sun. So time has both allowed the trees to grow and the sun to lower to where I am seeing a noticeable impact to my daily production. The trees are in my neighbors yard, but they are graded to a higher elevation than my lot which exasperates the unfortunate geometry. I know they would be amenable to sharing the fee to trim, if I push for it... but I am not sure I would get my $250 worth of extra production to knowing it will grow back! Tough call if it only impacts 2 or 3 months...

As time goes by, there is the temptation to cut more trees. So far I have only taken 3 out of
my 380. Lost 15 to the past severe drought. Just bought a stump cutter. Bruce Roe

[myfriendSUN]

For potential solar customers reading this: a heads' up - Often, a site survey done before purchase/install w/ a shading tool gives owners a heads' up on likely shading situations. Most reputable vendors have this capability.

My vendor/installer did that.
Just wonder would the shades be taken into consideration to estimate my system estimated output that I see on the Enlighten Manager screen.
I hope it does.

[J.P.M.]

My vendor/installer did that.
Just wonder would the shades be taken into consideration to estimate my system estimated output that I see on the Enlighten Manager screen.
I hope it does.

If you are asking me, like most things, I am ignorant of how that system works.

[SunEagle]

I appreciate the discussion on my account. I was just about at the point of calling my vendor when I made an observation that likely explains what I am seeing...
And jpm has already included this in his likely possibilities...
As we approach winter solstice the sun's path is lower and lower to the horizon. I have tree tops that are now in my panels line of sight of the sun. So time has both allowed the trees to grow and the sun to lower to where I am seeing a noticeable impact to my daily production. The trees are in my neighbors yard, but they are graded to a higher elevation than my lot which exasperates the unfortunate geometry. I know they would be amenable to sharing the fee to trim, if I push for it... but I am not sure I would get my $250 worth of extra production to knowing it will grow back! Tough call if it only impacts 2 or 3 months...

Isn't there a law that in CA your neighbor can't block or impede sunlight landing on your property? He might not have to cut the trees down but may have to keep them trimmed. Maybe worth looking into but also may p**s off your neighbor.

[J.P.M.]

Isn't there a law that in CA your neighbor can't block or impede sunlight landing on your property? He might not have to cut the trees down but may have to keep them trimmed. Maybe worth looking into but also may p**s off your neighbor.

Solar access laws do exist in CA. In this case, if the tree was there before the solar, you mostly lose. It's a bit more complicated than that, but for this case, new growth that can be documented as such may have some bearing on the situation.

[samotlietuvis]

You should ask your installer for test data of each panel before it was installed. I measured each panels performance before putting them up. Check if your array system VOC matches expectation, temperature compensated. Measure system VOC with DC disconnect off; system VOC is not related to irradiance - only temperature affects it, and panel goes to its Voc as long as it has light.

My system is expected to produce 9kwh in this season. I produced 8kwh yesterday (shading losses), and 7kwh today (shading + cloudy days). Everything is within expectation.

I just turned my system two days ago and I can clearly see when any of my panels get bypassed by bypass diode because of shading. My panel has Vmp is 55V. I see ~400V when all 8 panels are producing, ~350V when 7 panels are producing and 1 is turned off, 300V when 6 panels are producing and 2 are turned off. I visually confirmed that shaded panels correspond to the discretely lower voltages. If you can get access to each of your Strings Voltages, you would clearly see how many panels are not producing because of being shaded. In my case, the shadows will get "shorter" as the incidence angle gets smaller, and ~ March I expect no shading.

Like other people mentioned, we are 7 days away from winter solstice. In my case, I add my latitude of 34.6 deg to Earths inclination angle of 23.4 deg to get 60 degree solar incidence angle. The inclination angle at this time is the highest it gets. This has a few implications:
1) All the shadows will be "longer"
2) At the highest incidence angle the photons will travel through more atmosphere and get absorbed more which means less irradiance at your panels.
3) Highest incidence angle means highest reflected energy from you panels (Fresnel equations). You want photons to be absorbed but not reflected from your panels.

Something I observed in my neighbors installations is that the installer put as many panels as he could without regard to shading. My neighbors system is 6kw, but it is getting a lot of shading.