6 Panel Single Series String Array - But 2 Angles ?

[MrM1]

I have to stay in a Single Series String to keep the Array amperage in spec for the project. But .... If I install the array with all 6 panels facing the south direction, the lowest 2 panels will be in the shade part of the day.

Panels REC TwinPeak 2
Rated Power: 375W
Open circuit voltage (VOC): 48.00 V
Max power voltage (VMP): 40.1 V
Short circuit current (ISC): 9.96 A
Max power current: 9.36 A

So what happens if I split the direction up with 4 panels facing one direction, and 2 panels facing the other direction ? Or all 6 on the other side?

There is not much pitch to the roof. The drawing below is actually too steep you get the idea. And in July the Sun is almost directly overhead (may even be a little bit north at solar noon).
- All panels have to run in one series string
- What happens in each of these three scenarios?

I am working 3 Options

Option 1 - 6 Panels all facing South
Option 2 - 4 Panels Facing South and 2 Panels Facing North
Option 3 - 6 Panels Facing North

 

[MrM1]

Here are my Sun Angles
December 21


June 21

 

[HRTKD]

If you use option 1, a 2s3p wiring configuration would help with shading.

 

[MrM1]

Here is my actual roof and location at 1 hour BEFORE Solar Noon. This is the South Side where all 6 could get mounted (Option 1). I cannot go 3 wide because of the eve shade in the morning. And you can see the tree starting to creep in. Running the panels 3 down from the top would have them coming in about 5 ft from the gutter or about 2 x's the distance of the shade spot

 

[MrM1]

I can go the middle tier (the next one up) and then it is wider, will accommodate 3 wide and never gets shade. My existing 18 panels is on the top tier.

 

[MrM1]

Here is the North facing room in Mid April 1 hour BEFORE solar noon. Note the angle and distance of the Chimney shadow. The chimney is 4 foot tall. In this pic at the far right top corner is where I was thinking for the 2 panels of option 2. But how much am I loosing power wise if I put all 6 panels on this north roof?

 

[Supervstech]

If you tie different panel angles in series you will have massively reduced output all the time.
Only way to tie panels with differing angles is parallel.

 

[HRTKD]

Output from north facing panels would be a lot less than the south facing panels.

Placing panels on the lowest tier would work, but aren't you going to get shade from the second tier roof also?

 

[MrM1]

Output from north facing panels would be a lot less than the south facing panels.

Placing panels on the lowest tier would work, but aren't you going to get shade from the second tier roof also?

Middle tier does not take shade until late afternoon. I think it is the best option. That way they all stay together and is all south facing

 

[Hedges]

Specs of SCC?
Need to consider minimum MPPT voltage.
Whether you wire as strings in parallel, or in series & current pushed past bypass diode, it operates at reduced voltage.

The other alternative is that all in series it operates around Vmp, but the Imp of whichever panels are getting less sun.

Specs will also let us consider whether excess current is acceptable, and how much is clipped.

 

[MrM1]

Specs of SCC?
Need to consider minimum MPPT voltage.
Whether you wire as strings in parallel, or in series & current pushed past bypass diode, it operates at reduced voltage.

The other alternative is that all in series it operates around Vmp, but the Imp of whichever panels are getting less sun.

Specs will also let us consider whether excess current is acceptable, and how much is clipped.

These panels are for the EG4 Mini Splits. Direct DC input. 90-380 VOC and <\=12 amps

 

[Hedges]

In that case, 3s is minimum to have sufficient voltage

"Max power voltage (VMP): 40.1 V"

Will it survive having 20A Isc of panels connected?

"Short circuit current (ISC): 9.96 A"
"Max power current: 9.36 A"

Consider 3s2p.
With sun directly overhead in cool weather, you might get 18A, which would mean clipping to 2/3 available current (assuming inverter is smart enough not to hurt itself.) It would run a bit higher voltage to limit current, but power output rolls off rapidly, so only a bit above 2/3 available power.

Other times of the day/year, output would not exceed 12A so no reduction.

You do have to consider whether inverter would be damaged.

How about optimizers? Are you required to have RSD? Optimizer feature in addition is only marginally more cost.

Better would be if you hadn't bought the panels yet, selected a higher voltage panel not above 6A. Then 3s2p would be fine.

 

[MrM1]

No panels yet. My primary array is over 5k, but that's for battery and inverter. These DC mini splits will have their own arrays