micro-inverters or optimizers when shading is major issue ?

[jflorey2]

1. Will micro-inverters or optimizers give me the best efficiency (least performance reduction with partial shading), or are they pretty much equivalent ?
2. Is SolarEdge's system (optimizers and inverters) superior to other optimizers, as I've been led to believe ?

They are pretty much equivalent from an efficiency perspective. I would strongly suggest getting half-cell panels if shading will be a big issue. SolarEdge is about equivalent to Enphase in terms of efficiency. If you want to go with Enphase you might want to wait for the IQ8 inverters, since they add intentional islanding.

[nwdiver]

I'm planning a DIY grid-tied installation of 5kw or so, where shading will be a significant issue. Two questions:

1. Will micro-inverters or optimizers give me the best efficiency (least performance reduction with partial shading), or are they pretty much equivalent ?
2. Is SolarEdge's system (optimizers and inverters) superior to other optimizers, as I've been led to believe ?

Can you post a photo of what kind of shading issue you have? I think a lot of people forget that ALL solar panels have bypass diodes. If you have 1 string on 1 MPPT that string will handle shade about as well as SE or Enphase... no optimizers required. The only difference would be that a shaded panel will produce 0 energy without optimizers while with optimizers it will produce ~0. Not sure if the cost of an optimizer is worth getting ~0 instead of 0.

There's a lot of misinformation that shading one section of a string effects the entire string. This is 100% NOT TRUE. Bypass diodes effectively 'delete' the shaded portion and the unshaded panels continue producing unaffected. Each string does need to be on an independent MPPT but most inverters now have 2-4 MPP channels.

[Ampster]

I have only seen the press releases that there is an IQ-8 battery coming with some backward compatibility with IQ-7 inverters.

[RShackleford]

With Enphase IQ-7 micro inverters I bought ...

You know anything about this IQ8 technology supposed to be released soon ? I saw some vague claims about support of multi-mode.

[Ampster]

Roughly 100 feet of probably UF-B 10/3 for the micro-inverter, versus some pretty skinny THWN for the string. Some difference, but the main thing, I gather, is that with micro-inverters you're sorta stuck with the mfg'ers proprietary cables ($$$) whereas not so with strings (but, how are strings wired ?)

Strings are wired in series with the MC-4 connectors so you just need to buy an extension cable long enough to go from your last panel in the string to your junction box. Cut the extension, connect to the panels and to the positive and negatives in the junction box. You may need a combiner depending on how many strings you have. If using optimizers they connect to the panels and then each optimizer is connected in series. Some jurisdictions may require the DC runs to be in metal conduit with labels, which adds to the cost.

With Enphase IQ-7 micro inverters I bought a small quantity of proprietary cable for about $18 per panel connector. If you want to save and have the time and tools you can by the parts less expensively and it only takes two wires for IQ-7 wiring so a lot simpler than the old M-215 that I did years ago that had 4 wires.

[RShackleford]

Optimizers will take a lot less copper and wire complexity to get the power down
from the array, than micro inverters.

Roughly 100 feet of probably UF-B 10/3 for the micro-inverter, versus some pretty skinny THWN for the string. Some difference, but the main thing, I gather, is that with micro-inverters you're sorta stuck with the mfg'ers proprietary cables ($$$) whereas not so with strings (but, how are strings wired ?)

[RShackleford]

If part of the reason for doing PV is economic, that is committing to a lump sum invested in PV now against future savings from PV, I'd be real careful about doing so without a careful look at the economics of putting an array in a partial shade situation, much less a significant shade situation. That would incude getting a bit more quantitative about shade penalties.

I think if I were paying for $3/watt or so to a company to do the installation, my ROI would probably be un-tenable.

But yeah, I need to get a better handle on the shade penalty. One good thing though, I'm on 5 acres so I can take down any trees I please (and b myself, mostly).

But if I consider my sweat equity free, then I imagine I can do it for about half that (is that reasonable ?). I'd DIY even the electrical work, being a EE who has done a lot of home wiring (this is legal in my jurisdiction, subject to inspection of course).

[bcroe]

Optimizers will take a lot less copper and wire complexity to get the power down
from the array, than micro inverters. Bruce Roe

[J.P.M.]

If part of the reason for doing PV is economic, that is committing to a lump sum invested in PV now against future savings from PV, I'd be real careful about doing so without a careful look at the economics of putting an array in a partial shade situation, much less a significant shade situation. That would incude getting a bit more quantitative about shade penalties.

After that, and if I could make an economic case for any PV, I'd go with whatever kept the system complexity to a minimum and as much of the electronics off the roof as possible.

If the goal is PV for its own sake and economics have a back seat or of not much matter, go for it.

If getting the PV is with a view toward lower electric bills, the smart money knows that PV is usually about the last measure taken to achieve that goal and if part of a thoughtful plan, not usually the first measure for a lot of reasons. Reason: Significant $ investment compared to most other measures for what you get back. Reduce your use as much as lifestyle permits before generating power. You don't pay for what you don't use.

[scrambler]

That is part of the reliability and efficiency of the Tigo's. they do not include an MPPT, and rely on the Inverter ones instead.
they only take care of the panel optimization..
here are some article I came across that are interesting.

Comparing both

https://solarity.cz/blog/solaredge-vs-tigo/

Tigo review

https://mcelectrical.com.au/blog/tigo-energy-solar-panel-optimisers/

[RShackleford]

You also have Tigo's optimizer. Different technology simpler and supposedly way more reliable than SolarEdge.

I thought I'd read (somewhere on this site) that Tigo's MPPT is not as sophisticated and effective as SE's.

"Tigo is very different from solaredge. Solaredge has MPPT as well as buck and boost and monitoring.
tigo has buck and monitoring."

Haven't seen this corroborated anywhere though.

[scrambler]

You also have Tigo's optimizer. Different technology simpler and supposedly way more reliable than SolarEdge.

[foo1bar]

I'm planning a DIY grid-tied installation of 5kw or so, where shading will be a significant issue. Two questions:

1. Will micro-inverters or optimizers give me the best efficiency (least performance reduction with partial shading), or are they pretty much equivalent ?
2. Is SolarEdge's system (optimizers and inverters) superior to other optimizers, as I've been led to believe ?

I don't think there will be much difference in performance between Enphase and Solaredge for partial shading of some panels.
My guess is there are situations where one will be better than the other. So I think either one would be able to find examples where they can show they're a few percent better than the other.

I went with Solaredge.
It was cheaper overall (Enphase cables were expensive)
I like having less electronics on the roof.

[RShackleford]

my motto is : " Less is More"
What you should look at critically, is who do you call in 6 years if there is a problem ???

Hard to say who among SolarEdge, Chilicon, Enphase would still be in business in 6 years; I guess I'd bet on SolarEdge, since it appears to me that they control a LOT of the market, at least of big installers doing turnkey grid-tied systems. But with SE, you've got that big expensive string inverter that might die, whereas with micro-inverter it might just be one or two relatively-cheap units (unless some systemic issue makes most or all of them fail).

[Mike90250]

my motto is : " Less is More"
Less electronics on the roof = more reliability, all other things being equal. So i opt for optimizers. I have no experience with optimizers, and have no favorites. What you should look at critically, is who do you call in 6 years if there is a problem ???

Other question, is do you actually get enough sun to bother with ? If your roof is shaded, it's your call.