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Options for growing Fronius pv array

marciokoko

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Joined
May 29, 2022
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I am registered as info@nrgea.com but I no longer have that email.

So I have this fronius ig 3.0uni with a 12 panel single string configuration. Each panel is 255W 30.2V/8.4A. Because they are in series I get a total of 30.2x12 = 362V and 3060W. But I only ever get around 1500W max. So I was thinking of increasing my power.

There is obviously a limit to adding power whilst I keep my 3.0 inverter before I need to add a second inverter, which I do have sitting in a box.

The panels have no shade whatsoever, they are oriented 230 SW and according to my readings the sun rises and sets at 130 and 280 respectively; so they are oriented as best as possible. Incline is around 5-10 as I am in Honduras Central America.

So the power is dictated by the solar panel age (only about 8 years) or wiring or the inverter. The chart shows a decline from about 3000W to 2800W from 2016 to 2020. 2021 was anomalous because I moved houses and disconnected the pv array way before I was actually able to move. In 2022 we are near 1000W in May so I could assume the final production will be 2,400 and that would indicate possible solar panel degradation. However there is a possibility that it's also related to outages. This year, in this new area of town there have been considerable outages which of course reduce my production.

So if I were to increase the panels to maybe 6 more that would be 30.2x18=543.6V and 4590W but given I'm only getting (2400/3060W=78%) then I would get 3600W in theory.

The other option would of course be to install the second inverter (for which I'm not sure I have the necessary space) with its own 12 panel string. This seems safer obviously.

I'm wondering if you can recommend other options I am not seeing?

Thanks3B88069A-7178-4988-9176-CB811F33CBB9.jpegDBB44602-92AB-474A-AC0B-92DDABA68C2B.jpeg
 
I would not be adding any more panels in series to an ageing array without first checking to see what might be causing the sub-par performance and rapid performance decline.

Are the panels covered with lichen, or potentially damaged in some way? I think I would be checking the panels first.

Another option might be to replace the inverter with a more modern model which can more easily accept more PV, e.g. a Fronius Primo which has 2 x MPPT. But get the panels checked first.
 
Gotcha. I climbed up there and took some pictures. The panels were pretty clean tbh.

That's facing north btw.
 

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The panels have no shade whatsoever
OK, that's a very large tree trunk in that photo - definitely no shade being cast by overhanging branches, even though it is north of the roof?

On the left of the photo there looks to be a block shadow being cast on the roof, maybe a tree trunk? The shade seems to be a bit behind the panels but it may not always be?

At your latitude (~15° N) the sun is not always in the southern half of the sky. From late-March through to about mid-September the sun would rise and set to the North of East and West respectively, and spend some of the day in the northern half of the sky, reaching it's most northerly position around 20-21 June. On June 21 Sunrise is at ~66° and Sunset at ~294°.

That's a consequence of being at a latitude between the Equator and the Tropic of Cancer.

I also wonder about those large aircon units and whether they cast any block shadows on the ends of the arrays during June/July? hard to tell how close the array is to them. If they did cast shade along the edge of the panels then that can definitely reduce PV output by a lot. If they are casting such shadows then my recommendation would be to move the panels further away from them. Towards the cameraman in that photo.

Gotcha. I climbed up there and took some pictures. The panels were pretty clean tbh.

Agree, the panels look clean enough.

Another thing to check is whether all the panels are actually connected. I know it sounds silly but it wouldn't be the first time I've heard of an array where some panels were not connected at all.
 
And as an estimate based on PVwatts.org, I would expect an unshaded grid tied array without export limitation (and no extended power outages) in that general location, orientation and tilt to generate ~4 MWh/year.
 
Thanks. The tree is quite fast away, over 50 feet. Here is a picture from below next to that north wall. Add you can see there are no branches over the roof. The roof being on the left side of this picture and the right side being the north wall.

As for the block shadow on the left, did you mean this one? Because that is from the ac units. I don't remember the last te I was up there in the early morning but I'm about 99% sure the shadow from the ac units doesn't fall over the panels. If it ever does its closet to 7-8am which I don't even consider in the peak sun hour window.

I actually take screen shots of the production throughout the day and it's between 9-3pm and that is when I have noticed the reduced power production around 40-50%. In that window the sun is well atop the sky.

I'll check the panel connections and the shadows before ordering the panels but I think I'll get more panels even if it means setting up my other inverter, somewhere.
 

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As for the block shadow on the left, did you mean this one?
Yes.

Because that is from the ac units. I don't remember the last te I was up there in the early morning but I'm about 99% sure the shadow from the ac units doesn't fall over the panels. If it ever does its closet to 7-8am which I don't even consider in the peak sun hour window.
OK, good to know but worth checking as it doesn't take much block shading to vastly reduce production from older panels.

Good luck with it!
 
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