Solar strings on different elavation levels and number of panels allowed

[morgin187]

Hi I’m brand spanking new so sorry if I post something that’s wrong.

I’ve had a couple of quotes two of which I am Interested in. My problem is house is south facing and the main roof can accommodate 8 panels. On the same level I can have 2 additional panels facing west and on a lower level Extention have 2 more panels again facing west. The west side is likely to get shade on the panels.

I have been advised by one company they will be on two separate strings (front south facing and side west facing).

The other company is saying that the elevation and difference in shading can affect the west panels because of elevation and because the two at the higher level will get different sun than the lower. Also if all four are not working together they won’t kick the inverter into gear. Which company is correct?

Also will micro inverters make a difference to this problem or will the main inverter optimise for this and shading on some of the panel’s?

I’ll attach the two quotes with models of each component.

 

[binky]

Use micro inverters or Solaredge system for that. 2 panels is not enough to get the MPPT for the string working, 4 is marginal with shading issues. Your main South roof is fine.

 

[morgin187]

Use micro inverters or Solaredge system for that. 2 panels is not enough to get the MPPT for the string working, 4 is marginal with shading issues. Your main South roof is

Is it worth it for me to get this done. Sorry about the quality of the drawing.


The 8 panels is south and the two 2 panels are west. As you can see the elevation is different. Both of the two, 2 panels will be on one string and 8 panels on another. All will have micro inverters.

My option are
Better going with 8 panels south, 2 on the same elevation west. Total 10 panels

Or 8 panels south, 2 panels same elevation and 2 panels lower elevation. Total 12 panels

Or 8 panels south, 4 panels lower west. Total 12 panels

I’m leaning towards 8 south, 2 high and 2 low. Because the higher roof west will get more light than the lower but worried they won’t work because the other 2 lower might be in shade a lot of the time. I hope this all makes sense.

 

[binky]

Worth doing as much as possible, I would add more panels to the lower west array using solaredge optimisation or microinverters. They will give you a boost into the evening which is when people use most energy, and in high summer the sun sets almost NW, good for energy savings.

 

[Mrjmegson]

So what's the idea re West facing panels, and inverter start-up? The lowest start-up voltage I've seen for an inverter was 70v, most are 120-150v.

So as Binky says, 4 west facing panels aren't going to start an average inverter in anything but full summer sun.

So are you thinking using optimisers and making the west facing panels part of the south facing string?

 

[Mrjmegson]

Hypothetical theory question.

If you had all the panels individually wired into a combiner box (as Americans refer to them), so no strings, this would mean output wouldn't be affected from shading etc would it?

 

[morgin187]

So what's the idea re West facing panels, and inverter start-up? The lowest start-up voltage I've seen for an inverter was 70v, most are 120-150v.

So as Binky says, 4 west facing panels aren't going to start an average inverter in anything but full summer sun.

So are you thinking using optimisers and making the west facing panels part of the south facing string?

Idea is to have two separate strings. South on its own and the west on their own. But not sure if the west panels should be on the same level or if I can have two panels on the top west roof and two panels on the bottom west roof all will have optimisers.

 

[binky]

Idea is to have two separate strings. South on its own and the west on their own. But not sure if the west panels should be on the same level or if I can have two panels on the top west roof and two panels on the bottom west roof all will have optimisers.

I would go for solaredge, as a single string for all the panels. Think you can have something like a total of 21 panels on a single string ( double check that). Because every panel is then completely independent of the others, that will allow maxing out the roof space with panels and accomodate all shading issues. Solar works best on size, once you have paid for access scaffolding, it's cost effective to fit as many panels as possible off that scaffolding.

 

[morgin187]

I would go for solaredge, as a single string for all the panels. Think you can have something like a total of 21 panels on a single string ( double check that). Because every panel is then completely independent of the others, that will allow maxing out the roof space with panels and accomodate all shading issues. Solar works best on size, once you have paid for access scaffolding, it's cost effective to fit as many panels as possible off that scaffolding.

So will solaredge do the work of micro inverters? If there’s shade on say two panels the others will still work or if a panel becomes faulty?

One of the installers did recommend solaredge but changed plans to foxess.

Also what size inverter would be ideal for a 12 panel 410w each system. I’ll be planning on getting more batteries in future to get upto 7.5kw/10kw

One more thing was black panels do they loose efficiency when they get too hot. These sharp panels are black and look good but would rather go for more output than looks. They’re also half cell if that makes any difference

 

[binky]

So will solaredge do the work of micro inverters? If there’s shade on say two panels the others will still work or if a panel becomes faulty?

One of the installers did recommend solaredge but changed plans to foxess.

Also what size inverter would be ideal for a 12 panel 410w each system. I’ll be planning on getting more batteries in future to get upto 7.5kw/10kw

One more thing was black panels do they loose efficiency when they get too hot. These sharp panels are black and look good but would rather go for more output than looks. They’re also half cell if that makes any difference

Solaredge - have a read of their brochures, but basically yes.

I would say a 4 or 5 kw inverter depending on what you want to achieve with the batteries.

Black panels are the norm. All panels work by absorbing heat and can get too hot, which happens for about a week every year when we have a heatwave.

Half cells are good, lower cell temperatures and better resistance to dirt like bird poo on them.

 

[morgin187]

Solaredge - have a read of their brochures, but basically yes.

I would say a 4 or 5 kw inverter depending on what you want to achieve with the batteries.

Black panels are the norm. All panels work by absorbing heat and can get too hot, which happens for about a week every year when we have a heatwave.

Half cells are good, lower cell temperatures and better resistance to dirt like bird poo on them.

Thankyou so much I appreciate all the help.

The batteries are mainly for charging with solar and topping up with cheap rates. I’m thinking of eventually getting upto 10kw batteries.

Also want the batteries to power the house if there’s a power cut so will be getting a cut off switch and g99 application I believe.

Guess I’ll be going ahead with the solar edge inverter and the black panels.

My question though can I have all the south and west panels on one string. I thought they couldn’t do it so had to be on two separate strings and are they saying that because of cable’ing?

 

[binky]

Thankyou so much I appreciate all the help.

The batteries are mainly for charging with solar and topping up with cheap rates. I’m thinking of eventually getting upto 10kw batteries.

Also want the batteries to power the house if there’s a power cut so will be getting a cut off switch and g99 application I believe.

Guess I’ll be going ahead with the solar edge inverter and the black panels.

My question though can I have all the south and west panels on one string. I thought they couldn’t do it so had to be on two separate strings and are they saying that because of cable’ing?

You can with solaredge or microinverters, you can't with a standard inverter, or to be more precise, you can but it's a very bad idea

Have a read through the solar posts on here, there's a shed load of information. Give it all a read and ask more questions if you need to.