Single or multiple GTIs?

[inspec]

I am planning an installation that will include 4 x 250 W x 30 VDC mono panels, GTI and no batteries.

The panels will be connected in parallel to suit the 22 to 60 VDC input to the GTI(s).

My question is - is it better to use ONE GTI rated at 1000 W, or TWO GTIs each rated at 500W?

Please forgive me if this question has been asked previously - but I could not find it within earlier postings.

[Naptown]

What is the make and model # of the units you are considering.
And are you in the US or elsewhere ( it makes a difference)

[inspec]

Hi Rich. I was looking at SUN 1000G or Sun 500/600G GTIs. I already have a wind turbine connected to a SUN 1000 G WDL. I am in Mexico.

[computerpc101]

SUN 1000G/500 are Chinese made GTI, it is slightly better quality than some FreeBay model, however, It is overated wattages, 1000W GTI can handle really 850W of under only.

Those GTI are stackable, It means that you can keep on adding GTI, To use 1000W or 2x500W, Which really depend on unit prices plus connection wires cost, They are low voltage unit, If you use 30V solar panel, 1000w = 34A, which is quite large, you may consider to connect it for 60V configuration, 1000W = 17A which is fine for cheaper/smaller AWG wire.

[inspec]

Thank you computerpc101 - points noted.

Rich/Naptown - do you have any feedback, following my reply to your questions?

As part of this issue, is the question of connecting more than one panel (of same mfr/model) to one GTI.

While I guess it is better to have only one panel per GTI, is the system perfomance significantly affected by connecting 2,3,4 or 5 panels? I suppose the MPPT perfomance of the GTI could be compromised . . ?

[Mike90250]

Be sure to verify the effiency of the GTI that you are looking at. Utility grade, UL certified units, are generally 95% efficient. knockoffs are 70-85% efficient, and therefor generate a lot more heat, and are more likely to fail early.

So it's a trade off, 2 unite would dissipate heat better, but may have lower efficency than 1 unit.

[inspec]

Thanks Mike. I am going the Enphase way. Paul

[Naptown]

Thanks Mike. I am going the Enphase way. Paul

A much better route to go. More expensive. But better quality and efficiency. Plus you can add 13 more panels in the future

[computerpc101]

Good Idea using Enphase on each panel, It is a well build unit, Better than Sun GTI and hassle free and worry free.

Although in theory, Parallel connecting solar panels to MPPT GTI should be same power, however, In Real world, it doesn't.
Test1 on Sunny day with 2 FT cable only (low wire resistance lost)
New Panel 1 with same GTI get 180W input DC power ( not output power, not GTI convertion lost)
New Panel 2 with same GTI get 190W input DC power

Parallel both Panel 1 and Panel 2 with same GTI should get = 180W+ 190W = 370W
real world, I got 345W, It is 10% lower

Not sure why, Both panels are same, May be, Power curve is slightly difference, MPPT point, Their maxium power point's voltage, One panel is 0.3V higher than other.

[aoyiteled]

I am a beginner, in learning Mod note - OK - Welcome to Solar Panel Talk but forget the links