position of extra string

what? · 26-08-2022 9:11am #1

hi

I have to option of another string of 4 panels.

Panels faces ESE, so getting from sunrise, thru noon till afternoon when sun goes over to front

Front faces WNW.

Adding the string to the already in place panels is the most obvious, but I'm missing on 2-3 hours of light in the summer.

Am i overthinking the placement?

Thanks v much

slave1 · 26-08-2022 9:35am

What wattage is your current panels, are they on a single string, is your inverter MPPT?

what? · 26-08-2022 10:47am

ta

Panels 385

Second string/MPPT, I don't know that, Installer tells me yes

Model is MIN 4200TL-XE if that helps

slave1 · 26-08-2022 12:30pm

Grand, I'm by no means an expert but if you have a string free (that Inverter is dual string) then all looks good, get as high a wattage panels as you can manage, as they are on a different string they do not have to be 385w

what? · 29-08-2022 8:43am

Cheers Slave1!

Does anyone have an opinion of the best position to face the panels?

On the flat roof thay could be pointed due south, or on the front of the house have a more westerly orientation.

i,e, bump up my daily production or elongate my catchment hours.

Budget dictates one string only

thanks v much

bullit_dodger · 29-08-2022 8:47am

https://www.boards.ie/discussion/comment/119536081#Comment_119536081

Pretty much always south. Those ENE panels would be effectively useless in winter, least with the South ones you'd get something from them.

slave1 · 29-08-2022 11:11am

If West then they would be good for PV into the evening, I suppose a lot depends on your personal usage, if you have no battery what use is higher generation during the day if you are not there to consume it?

DC999 · 29-08-2022 11:33am

Adding to what others have said, if you've no battery then add to a new roof orientation (don't add more panels on the same orientation). Then you decide which orientation allows you use the power when it's available (West for evening / dinner time, or South for middle parts of day).

bullit_dodger · 29-08-2022 11:56am

Fair points lads about being there to use it, but I was thinking in terms of FIT. If you put them on the WNW, then those panels are going to produce next to nothing in the winter. I know as I've East/West split myself and my West do very little. If you are even more north facing than West then you can expect nothing from late Oct to Feb.

With south and FIT giving you "something" for anything you export that you might miss during the day......it would seem the better choice - albeit, a lot of this type of stuff is down to personal preference and not right/wrong.

what? · 29-08-2022 12:07pm

Thanks v much for the replies folks

tis true, I'd much prefer a right/wrong binary decision.

That said, no battery, currently old backwards meter, I'm leaning to facing them south.

Again ta very for the responses

bullit_dodger · 29-08-2022 12:40pm

https://www.boards.ie/discussion/comment/119537098#Comment_119537098

Makes sense with a backward facing meter to maximise your output.

DC999 · 29-08-2022 3:08pm

Ah @bullit_dodger, ta for explaining that. I've NW on 1 roof so at least now I know I'll get SFA from that from the end of this month. Output on that is lowest compared to my SE and SW - that explains it. Every day is a school day in solar land :)

bullit_dodger · 29-08-2022 3:31pm

https://www.boards.ie/discussion/comment/119538162#Comment_119538162

Ahh, you'll aways get "something" from them DC999, but it'll be diminishing a lot come Oct. For example, here's the expected output of 1Kwp in panels from NWN

Compare that to 1Kwp facing due south

You can see while in summer, they are reasonably close (the North west facing ones doing 80% or so the production of south), but in winter, the same panels only do about 20-30% of south.

Good site to play around.... https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP%20that's%20the%20calculator%20for%20Europe

(Don't worry it's not as daunting as it looks)