One inverter with 20 strings All string facing one orientation or 10 strings oposite?

[Bendesa1962]

Hi All,

Imagine a roof with the same tilt and one roof faces east and the other roof faces west. The two roofs are exactly the same.

We have inverters to which 20 strings can be connected. Do we install 20 strings in 1 direction, for example towards the west or
do we divide the number of strings over the two roofs.

So 10 strings to the east and 10 strings to the west

We are talking about a Grid Tied PV System

What do you guy think?

Kind regards

Ben

[Mike 134]

I suggest running the numbers here for the correct answer presuming no shading on either side.

PVWatts Calculator (nrel.gov)

[Bendesa1962]

Hi Mike,

Thats a good point of you. And yes there will be no shading on either site
Regards

Ben

[solarix]

The only advantage to two orientations is you can use a smaller inverter. Or if you are dealing with a grid tied application with a time of use rate plan, you would want all your panels on the west side. Another factor is if you needed more than about 22 panels, but the largest inverter allowed by the the 20% backfeed rule is 7.7kW, then using multiple orientations allows for larger arrays.

[SunEagle]

Hi All,

Imagine a roof with the same tilt and one roof faces east and the other roof faces west. The two roofs are exactly the same.

We have inverters to which 20 strings can be connected. Do we install 20 strings in 1 direction, for example towards the west or
do we divide the number of strings over the two roofs.

So 10 strings to the east and 10 strings to the west

We are talking about a Grid Tied PV System

What do you guy think?

Kind regards

Ben

I presume you mean 20 panels and not "strings". As for how to connect them others have given you good information.

[bcroe]

Connecting in parallel, panels or strings with different orientation
works well because at a given temp the voltage will vary little. That
happens to the extreme here, a clamp on DC ammeter shows all
panels still make a positive contribution per their ability at any time.
Bruce Roe

[DanS26]

Two string inverters is preferable to one large inverter even if the cost is somewhat higher for a couple of good reasons.....

1. A matched set of inverters with matched set of inputs will constantly give you feedback on the health of your panel system. A fall off of production in one inverter will be immediately noticed, analyzed and corrected if needed. A falloff of power in one large inverter may not be noticed for months maybe even years.

2. If one inverter is down you are still producing power.

[Bendesa1962]

I presume you mean 20 panels and not "strings". As for how to connect them others have given you good information.

Actually I do mean 20 Strings. For example a 100KW Inverter. 20 strings facing East, West or 10 Strings facing East and 10 strings facing west

[Bendesa1962]

Connecting in parallel, panels or strings with different orientation
works well because at a given temp the voltage will vary little. That
happens to the extreme here, a clamp on DC ammeter shows all
panels still make a positive contribution per their ability at any time.
Bruce Roe

Hi Bruce, thanks for your answer. I do apriciate it. You talk about different orientations, I talk about different tilt. Same orientation

[Bendesa1962]

Hi All,

Imagine a roof with the same tilt and one roof faces east and the other roof faces west. The two roofs are exactly the same.

We have inverters to which 20 strings can be connected. Do we install 20 strings in 1 direction, for example towards the west or
do we divide the number of strings over the two roofs.

So 10 strings to the east and 10 strings to the west

We are talking about a Grid Tied PV System

What do you guy think?

Kind regards

Ben

Same question but not facing East & West but North & South, Would it make any difference?

[bcroe]

You talk about different orientations, I talk about different tilt. Same orientation

My orientation is intended to include both facing direction (degrees
of the compass) and tilt. Bruce Roe

[J.P.M.]

Hi Bruce, thanks for your answer. I do apriciate it. You talk about different orientations, I talk about different tilt. Same orientation

By most common understanding and convention, an array's or a panel's orientation is specified by two parameters:
1.) It's tilt. Horizontal being zero degrees and 90 degrees being vertical.
2.) It's azimuth with true north being 0 degrees, east being 90 degrees, true south being 180 degrees and west being 270 degrees.

It's also usual to specify an array's height above mean sea level and often latitude and longitude.

There are some uses and sense for calling out for tilts greater than 90 degrees but that's usually found in applications such as for bifacial panels or for high albedo applications, and some resource assessment calculations. However, there seems to be no agreed upon convention for such applications at this time that I'm aware of.

For most common applications, if two arrays have the same azimuth but different tilts, they have, by convention, different orientations. Similarly, if two arrays have the same tilt but different azimuths, they have, by convention, different orientations.

Take what you want of the above. Scrap the rest.

[SunEagle]

Actually I do mean 20 Strings. For example a 100KW Inverter. 20 strings facing East, West or 10 Strings facing East and 10 strings facing west

Wait. you have 20 strings? How many panels are you installing and is the 100kw system a commercial one. It can't be for a home.

[Bendesa1962]

Well it's absolutely for a commercial project.

In total around 2800 PV Modules

But I think for the sun it doen't make any difference either it's residential or commercial (-:

[Mike 134]

Well it's absolutely for a commercial project.

In total around 2800 PV Modules

But I think for the sun it doen't make any difference either it's residential or commercial (-:

Your design engineers will give you good advice.