NE/SW Installation

[jason121]

Any thoughts on installing a split system on North east and South West. Not sure about if the figures add up, being on house and having the cost of two scaffolds. Looking at 9 x 250watt on SW and 7 x 250watt on NE. Maybe use a power-one 3.0

 

[SibertSolar]

What's the pitch Jason?

 

[jason121]

35 Degree

 

[SibertSolar]

Hmm..I reckon your gut feeling is right but have you tried running any numbers on the PowerOne (or any other) software? Rough location?

 

[jason121]

PVSOL does not do split systems. Power one string tool, don't allow for orientation. Roof only 10 degree from east

 

[whinmoor]

Is it a nice, easy unshaded roof? Scaffolding company shouldn't charge double for a second scaffold.

If you can do 16 panels in a day on nice tiles, it may make sense. Once you've got your gear there, it's not much more work to do the second roof surface otherwise the roofing guys may be clocking off at lunchtime!

 

[zeljuga]

Use Thin film panels on the NE side and performance should be OK then .

 

[jason121]

My concerns are the NE panels going to return enough output

 

[whinmoor]

I think a NE panel will generate about 75% of the electricity of a south-facing one. I would probably choose polys for a job like this.

 

[SibertSolar]

Thin film isn't a bad idea, if feasible. Wouldn't advise using a transformerless inverter with them though, although it is possible depending on module/inverter type. Polys prob best bet. PVI-3.0 maybe?

 

[jason121]

Phono 250 poly with power0ne 3.0

 

[SolarCity]

Unless you have a lot of room, I doubt thin-film would be a good option.

PV Sol Expert does do dual aspect modelling.

If you give me the location, panel you intend to use, inverter choice etc. then I'll model it for you when I get back from site later.

 

[jason121]

Sleaford Lincs
16 X Phono PS250P-U/20
7 on NE 10 degrees of east
9 on SW
POWER0NE 3.0

 

[dansk]

PVSOL does not do split systems. Power one string tool, don't allow for orientation. Roof only 10 degree from east

Hi Jason, not sure which PVSOL your on - but you can do twin array and model N/S arrays using a twin tracker - im on an old version 4.0 and can do it - hope this helps you.

 

[SolarCity]

Sleaford Lincs
16 X Phono PS250P-U/20
7 on NE 10 degrees of east
9 on SW
POWER0NE 3.0

10 degrees off east towards north east? Shouldn't be an issue at all.

 

[jason121]

Yes. Dansk said PVSOL can do twin trackers any ideas ?

 

[SolarCity]

Okay, first of all the inverter looks a bit undersized.

Anyway, I get a yield of 2,898kWh from that setup using Sleaford's climate data.

That works out at 1,696kWh from the south west array and 1,202kWh on the north east array.

For comparison reasons, if the inverter was changed for an Aurora 3.6 then the yield comes in at 2,878kWh - which surprised me and shows the importance of sizing inverters correctly.

For further comparison, to get a good idea of how 10 degrees towards north affects the yield, I also modelled this with 8 panels on both sides - the yield comes in at 2,881kWh with the SW array coming in at 1,506kWh and the NE array coming in at 1,375kWh.

The figures definitely seem to be stacking up.

 

[jason121]

That's help me a lot thank you. The building is 7.7m long so I would like to do 8 and 8 split but will look odd on the roof.

 

[SolarCity]

The more panels you get on the south west roof, the yield increases (Maybe stating the obvious but from the figures I've posted, it seems to have a pretty big effect)

 

[jason121]

I don't wont to lower the voltage on the NE to much so its a compromise between the two

 

[jason121]

Thanks guys for all your input, especially solarcity cheers, next round on me.

 

[Ian-LS]

Agree should be about 75% of a perfectly south facing roof with no shading. Only 5% worse than a directly east facing roof.