What to do? Some solar panels shaded late in the afternoon

[callussun]

I just finished installing solar panels with Tesla. I asked to put all the solar panels on the west side thinking it's better for peak hour performance. There is a little bit of shade from the chimney from the west side but it only covers a small portion of the roof. However, I just learned that Tesla's panels are connected in series, one panel being shaded can impact the production of all the other panels. As a result, this design will negatively impact the solar output late in the afternoon in summer time. Please see the attachment for the solar panel design and the roof view.

Tesla never told me about this when I asked to change the default design. Does anyone have advice on what I can do about it for remedy?

Thanks!

 

[yblaser]

One or more shaded panels will not affect the production of the other unshaded panels in the string. No remedy needed. Google "bypass diodes" for more info.

 

[ucmndd]

Also, we are close to the winter solstice with the sun as low in the sky as it gets. You will likely find shading issues greatly reduced in the summer.

 

[tfan2018]

Having panels partly shaded better than no panels

 

[zƬesla]

Use mirrors:-!

 

[jboy210]

Use mirrors:-!

Mirrors orbiting in space are the best to reflect the sun at an angle that illuminates the panels when the sun normally will not. Like at midnight or when a tree gets in the way.

 

[zƬesla]

Mirrors orbiting in space are the best to reflect the sun at an angle that illuminates the panels when the sun normally will not. Like at midnight or when a tree gets in the way.

They don't have to be in space. Plus you can use more than one to work around angled shadows. -)

 

[CrazyRabbit]

Remove the chimney! ;D
Make sure that string is on one mppt by itself.
You picture looks like summer, it is green out.
I would put the unshaded panels on one string and shaded on another string. Something like this:

 

[Jeremy3292]

One or more shaded panels will not affect the production of the other unshaded panels in the string. No remedy needed. Google "bypass diodes" for more info.

Tesla uses string inverters and not micro-inverters so wouldn't any shading still be an issue? Can you explain further? Thanks

 

[yblaser]

Tesla uses string inverters and not micro-inverters so wouldn't any shading still be an issue? Can you explain further? Thanks

Looks like an image made by someone selling microinverters. That's not how a string inverter works. Each panel has multiple bypass diodes so that if the panel is shaded the current in the string can bypass the solar cells in then panel. The rest of the panels in the string function normally. If the shading is not complete the inclusion of multiple diodes allows for only a portion of the shaded panel's solar cells to be bypassed retaining some production in the shaded panel, but again it does not affect other panels in the string.

Microinverters do add redundancy to the system so your whole system doesn't get taken down by a single failed inverter.

See the below thread for a good discussion on microinverters and optimizers..

Optimizers... what are they good for?

I see a lot of significantly misinformed posts with regards to module level optimization. This topic frustrates me because it's a large source of wasted capital as far as solar installs go. By and large there is virtually no financial benefit to using optimizers. Even with the rapid shutdown...

teslamotorsclub.com

 

[dafish]

While I own micro-inverters personally, I appreciate and understand DC string inverters well enough. What you want to find out is if Tesla uses "DC Optimizers" in your system (I don't know Tesla solar systems). DC optimizers address the majority of your concern, basically deliver the same isolation capabilities of micro inverters.

 

[CrazyRabbit]

While I own micro-inverters personally, I appreciate and understand DC string inverters well enough. What you want to find out is if Tesla uses "DC Optimizers" in your system (I don't know Tesla solar systems). DC optimizers address the majority of your concern, basically deliver the same isolation capabilities of micro inverters.

That was for solaredge inverters only.

 

[Vines]

Looks like an image made by someone selling microinverters. That's not how a string inverter works. Each panel has multiple bypass diodes so that if the panel is shaded the current in the string can bypass the solar cells in then panel. The rest of the panels in the string function normally. If the shading is not complete the inclusion of multiple diodes allows for only a portion of the shaded panel's solar cells to be bypassed retaining some production in the shaded panel, but again it does not affect other panels in the string.

Microinverters do add redundancy to the system so your whole system doesn't get taken down by a single failed inverter.

See the below thread for a good discussion on microinverters and optimizers..

Optimizers... what are they good for?

I see a lot of significantly misinformed posts with regards to module level optimization. This topic frustrates me because it's a large source of wasted capital as far as solar installs go. By and large there is virtually no financial benefit to using optimizers. Even with the rapid shutdown...

teslamotorsclub.com

Also, modern inverters like the Tesla inverter have such a wide voltage range that I think even 2 panels in a string will hit startup voltage (depending on the panels) so I think a string of as small as 3-4 will work barely though it may be out of best MPPT range and rated efficiency.

This is important because a bypass diode drops the panel out of production when it has a hard shade. So on a string of 6 panels, 1-2 shaded panels will be bypassed with the diode, and the other 4 panels can produce most of full power. If 4-5 panels are shaded, the remaining 1-2 may not fire at all, because the startup voltage of the PV inverter is not reached.

Microinverters, and Solar Edge inverters do harvest better in any partial shade condition, but even Solar Edge inverters are not immune to the startup voltage problem. Typically the DC-DC optimizers have a maximum output voltage of about 80V and the target voltage for the SE inverter is 350-400VDC. So if you have a string of 10 Solar Edge optimizers and modules, you can only afford to have about 5-6 modules see hard shade before the entire string might drop out of production. The remaining 4-5 modules in the Solar Edge String will not produce much if any power in these conditions.

 

[Jeremy3292]

Looks like an image made by someone selling microinverters. That's not how a string inverter works. Each panel has multiple bypass diodes so that if the panel is shaded the current in the string can bypass the solar cells in then panel. The rest of the panels in the string function normally. If the shading is not complete the inclusion of multiple diodes allows for only a portion of the shaded panel's solar cells to be bypassed retaining some production in the shaded panel, but again it does not affect other panels in the string.

Microinverters do add redundancy to the system so your whole system doesn't get taken down by a single failed inverter.

See the below thread for a good discussion on microinverters and optimizers..

Optimizers... what are they good for?

I see a lot of significantly misinformed posts with regards to module level optimization. This topic frustrates me because it's a large source of wasted capital as far as solar installs go. By and large there is virtually no financial benefit to using optimizers. Even with the rapid shutdown...

teslamotorsclub.com

Thank you. So you are saying Tesla uses these bypass diodes in their panels, correct?

 

[yblaser]

Thank you. So you are saying Tesla uses these bypass diodes in their panels, correct?

All panels use bypass diodes. They are also a safety feature so that the panel doesn't catch fire.

 

[Jeremy3292]

All panels use bypass diodes. They are also a safety feature so that the panel doesn't catch fire.

Thank you. I am getting Tesla to install my system and will have an all south facing array. My roof is a very simple roof, so all the panels will be in a rectangle shape minus any gaps for roof venting.

My concern is I will have some shading issues in the morning and evening as my property is surrounded by trees. So I’m trying to learn about all these things beforehand - MPPT, bypass diodoes, optimizers, etc. to make sure Tesla doesn’t screw me with a shoddy install.

 

[yblaser]

Thank you. I am getting Tesla to install my system and will have an all south facing array. My roof is a very simple roof, so all the panels will be in a rectangle shape minus any gaps for roof venting.

My concern is I will have some shading issues in the morning and evening as my property is surrounded by trees. So I’m trying to learn about all these things beforehand - MPPT, bypass diodoes, optimizers, etc. to make sure Tesla doesn’t screw me with a shoddy install.

If you haven't already I would recommend requesting the full project plan from Tesla which will show exactly how they intend to wire everything up.

 

[dafish]

Not my area of expertise, but I would not consider a bypass diode functionally equivalent to a DC optimizer. Might want to slow down and ask more questions.