How did you decide? Microinverter vs Optimizer & PV Inverter

[Versailles79]

Hello All,

I am a newbie to this forum and need the help of great contributing members here. I have been so amazed by all the technical knowledge and deep research by each and everyone of you.

I have no clue on engineering and technicals of a system. My research thus far has concluded that:

1) I want an efficient system given my limited roof space. So I have narrowed down to SunPower 335 and 345 and LG 320s.

2) I have shading so going with microinverters

3) reliability and warranty are very important as if something breaks, I have no idea how to fix

I was just about to pull the trigger but then started reading more and realized the type of inverter, the size of inverter, the brand, the brackish system, etc are all very important as well. So now I am completely lost on how to evaulate. I got the following three proposals. Can you all smart people help me decide which is the most reliable system and if the proposed accessories are sufficient and any good (what size inverters do I need)? Thanks in advance.

Proposal #1
24 LG320W with Tigo Optimizers (maximizers) – 7.68kW system.
ABB PowerOne 7kW inverter to allow for system size increases if needed (upsized inverter at no extra cost)
QuickMount premium flushing solution
Monitoring hardware and software included. Tigo system

Proposal #2 - I think SunPower inverters were embedded into each panel. Why do I need an ABB PowerOne inverter?
23 SunPower SPWR335W with Tigo Optimizers (maximizers) – 7.71kW system.
ABB PowerOne 7kW inverter to allow for system size increases if needed (upsized inverter at no extra cosT)
QuickMount premium flushing solution
Monitoring hardware and software included- Tigo monitoring

Proposal #3 - I assume the monitoring system is included even though it is not stated? SunPower has its own monitoring system. Does it automatically come with the panel purchase or is it something I have to pay extra for?
7.94 kW (DC), 6.90 kW (AC) SunPower System 23 x SunPower AC Module; X21-345-C-AC
InvisiMount Mounting System
13 x Factory-integrated Microinverter
3 x Factory-integrated Microinverter
3 x Factory-integrated Microinverter
4 x Factory-integrated microinverter

Thank you for your generous help!

[entgegnen]

A wise move, best done before system sizing. Before signing a contract is still good, if a bit late. Along with/after that, I'd suggest considering a look at the benefit/impact of possibly resizing the system (downward) based on the results from any conservation measures actually incorporated as a result of the audit.

While I certainly see this point, I had a different perspective. My goals are not exactly in-line with the utility or in-line with the (economize first, then go solar approach)... I want to approximate my system "output" with my usage at the median life of the system. Assuming a 25 year system life, and a certain fractional percentage of panel degradation year over year, if my system outputs 90-93% at year 12.5... I want to be in the position of NOT buying 7-10% of my electric needs from the utility (at that time in 12.5 years). So, within certain parameters, I'm more in favor of pushing the limit of what the utility will permit today... and creating a rolling buffer through things like incandescent - LED bulb change out... Air Conditioner upgrades, etc... so as system output slowly recedes, the shortfall will be addressed through such "simpler" upgrades... so that I have the largest overall period of not buying from the utility....

Certainly the economize first, then get solar to meet 100% of your needs is a reasonable one, and has the advantage of being able to say, if your system is not outputting enough, just add a few panels later... I didn't want the incremental add on of parts/labor... especially when retrospectively, adding the extra capacity (or planning out the more optimum capacity today) is a more efficient use of money long-term (just my perspective).

And all environmentalism aside, this is all about the Benjamins.

[J.P.M.]

Two of the best comments I've received (on this and another thread) have been to (a) do a quick energy audit and see if I might benefit more cheaply from a few common sense economizing measures before jumping all in.

A wise move, best done before system sizing. Before signing a contract is still good, if a bit late. Along with/after that, I'd suggest considering a look at the benefit/impact of possibly resizing the system (downward) based on the results from any conservation measures actually incorporated as a result of the audit.

[entgegnen]

Hey everyone-

1. I just want to say thanks for the debate/discussion. It has really helped me in deciding what to do. Over the last week, i've gone back and forth a few times.
2. I think at the end of the day, all three can be terrific options (string, optimizer, micro) depending on site survey, budget, usage needs, reliability, future adaptability, etc.
3. Two of the best comments I've received (on this and another thread) have been to (a) do a quick energy audit and see if I might benefit more cheaply from a few common sense economizing measures before jumping all in; (b) to understand that year over year there will be incremental improvements in the types of systems... but that the latest and greatest tech may not be the best value purchase $/watt... the more important thing is to jump on the train instead of always waiting for the "next" train.

4. So I've settled on an installer, a system, and a final cost. The installer didn't have the "lowest price" but was hands and away the most knowledgeable of the contractors I've spoken to and didn't steer me towards any one system over any other. (While not the lowest, the price was competitive-reasonable). I am also confident that he will be good to my roof. (And no sub contractors was a big plus). I've researched his contractor's license and I didn't find anything adverse.

5. I'll come back in a few weeks after everything is up and running to provide more details. But again, big thanks to Sensij, ButchDeal, and others who have shared their insight.

[Engineer]

Yeah you said that already and I'm not disputing it, I'll say a third time I'm simply relating the anecdotal from one installer. Regardless as you say Enphase is fixing the situation and making it right. Enough, peace

[sensij]

The M190 problems are well documented in this forum and elsewhere. Enphase started purging their own forum of discussion of it a couple years ago. They are reaching out to owners of the M190's to either replace them, or modify the firmware to allow less power. A mess.

More recent products have been better, but I don't think they have earned anything close to a reputation as reliable yet.

[Engineer]

I'm just relating my installers experience which is that they've experienced very few failures of the many Enphase systems they've installed. They've also said that the string inverters not uncommonly fail. In fact there's a guy who buys up the broken ones they replace, fixes and resells them. He comes by when they've got a dozen or so.

Anecdotal but interesting.

[sensij]

I don't think enphase has earned the designation of "reliable" yet. The M190 was a disaster, and they have been very tight lipped about what went wrong and how they fixed it in the M215 and later. I would reserve judgement on reliability until they can prove they have a product that can last at least 5 years in the field.

[Engineer]

My reasons for getting 38 Enphase S280 inverters on my LG315 panels

• I live near Enphase headquarters and know many of the engineers (indeed used to work with them) who are over there now; these guys are the best. So I trust the engineering and the company, plus would like to support a local business.
• From an engineering standpoint the micro solution is the best hands down as ltbighorn pointed out, reliability, distribution, etc. My installer (another local business been around for decades) says they've seen maybe one Enphase failure that was one of the first ones.
• Data is good and Enphase delivers the most of any solution. Temperature, voltage, current etc per panel over time.
• I have partial shading issues
• I wanted an expandable system (I first put in 22 panels, now am putting in a total of 38 and might go 42 eventually (max for three strings of S280's)
• I would like to try the Enphase battery later this year
• An AC coupled system is superior IMO
• I didn't want a big ugly inverter in my garage

Technically they're both fine but I think micros have the lead, and I just like them better anyhow.

[sensij]

Thanks again Ltbighorn. Those are compelling points.

Sensij - I think you have a solar edge system. Knowing everything you now know - from this forum and from your own experience - would you still have gone solar edge (back then)? Or asking a different question, based on how things developed since then, would you go Enphase today....?

I love how much knowledge I've been able to extract from my system by looking at the optimizer data. Seeing how voltage and current respond to the changes in environmental conditions has provided some very good real-world data to support the theory, and I am not sure I would have been able to learn as much from any other system. I have some shading on the roof with a ridge immediately to the west (with some palm trees on top). For those reasons, I would still choose SolarEdge for that system if I had to go back and do it again.

For my next system (I am moving soon), I expect to have less shade, and less interest in the granular data. Until I really dive into it I don't know for sure what I will do, but I suspect that an inverter like the Fronius Primo will be my first choice. It is the least expensive high quality grid-tie inverter that I know of.

I *might* consider spending extra to put in a bi-modal inverter to support peak shaving, since I intend to be in this house a long time and anticipate that eventually it will be cost-effective. Really though, that is probably the next inverter after the Primo fails. I like that a simple string design is more easily converted to a generic bi-modal system than either SolarEdge or a microinverter system would be; I'm not a big fan of the proprietary designs that seem to be a part of SolarEdge's business plan.

As i understand it, as battery systems are considered by the CPUC in the context of peak shaving, it is possible that approval for those systems will depend on showing that the battery charging is coming from a renewable source, not just charging from the grid at night and then discharging during the day. Still a lot of policy to be figured out there, but for that reason, I tend to like DC coupled storage systems more than AC coupled.

As for micro-inverters... while I respect anyone who weighs the pros and cons objectively and concludes that they are the right choice, I would not put them on my roof unless I could easily access each one in the event of a failure. Count me among those who thinks the optimizers should last significantly longer than the micros will, although the number of infant mortalities of optimizers that have been reported in the forum make me less sure of that than I once was.

[ButchDeal]

2) of course the AC battery does not give the option for backup power but the StorEdge does.
3) SolarEdge = profitable, Enphase = not profitable.
6) if they are on the same trunk they will interfere with communications. They would likely need to be on their own trunks to communicate, then to the same single AC disconnect.

[entgegnen]

Thanks again Ltbighorn. Those are compelling points.

Sensij - I think you have a solar edge system. Knowing everything you now know - from this forum and from your own experience - would you still have gone solar edge (back then)? Or asking a different question, based on how things developed since then, would you go Enphase today....?

[ltbighorn]

entgegnen, responding to your points.

1. If you have the 25-year warranty and are comfortable relying on the company for the next 25-years to support that warranty, then getting the warranty on the SolarEdge inverter makes them equal. From what I've seen anecdotally of central inverters (not necessarily SolarEdge ones, since they're newer), they do fail sometime between 1 and 2 decades, and if the company isn't around to replace it, then you're on your own. With a non-SolarEdge inverter, this may not be so bad -- in 10-20 years it's likely that inverters will be even cheaper and more capable and you could install any brand. But with a SolarEdge inverter, you're dependent on either the company existing and supporting you, having access to a cold spare, or rewiring to remove the optimizers so you can use another brand of inverter.

Now I wouldn't necessarily let that stop me if I liked the SolarEdge for other reasons. But I'm generally pessimistic on young companies being around in 25 years, so I like options that leave me with flexible options down the road. Because who knows what the future holds?

2. Re StorEdge -- to me the modular AC battery just seems more practical. the StorEdge is yet another thing tied to your SolarEdge inverter -- more lock-in, more things all depending on a single device. While the AC battery is dependent on the Envoy-S Metered gateway (mostly so it knows optimal times to charge and discharge), it is not dependent on the microinverters in any way. In fact someone who doesn't even have solar panels could benefit from time shifting with the AC battery setup. One can also buy in small increments - like panels, at a certain point, the more dollars spent, the lower the return, as you're offsetting less and less electricity. 1.2 kwh or 2.4 kwh might be sufficient to get me through the rate peak -- I might not be able to capitalize on additional capacity. But these are so far off from practical today that it's of course hard to really say. But again, I like options and less upfront spend. Keep your money for later when you have more info on what you need, and prices and technology have improved even more.

3. Enphase's stock is certainly doing worse, but they seem sustainable to me. They're investing a lot in future products. They strike me as a company that may not do well on investor returns for a long time, but still make solid products and money to pay for ongoing development. SolarEdge is hot now, but Enphase was the hotness just a moment ago. Maybe SolarEdge will be huge, maybe they'll struggle. I don't know. I know that if Enphase goes out of business, I have low-cost options that don't require me to invest in advance or limit my future choices. I can wait and see.

5. Clipping -- what everyone is saying. Play with some PVWatts simulations and tweak the DC-to-AC ratio. It'll give you an idea of how much you're likely to lose from clipping. Good chance it won't be enough to buy a yearly movie ticket.

6. sensij makes a good point about the trunk cabling. Ultimately microinverters are just feeding back standard 240V AC. If you can get cabling adapters, anything else that outputs 240V AC should be able to play along. They may not be monitorable by the Envoy-S, but they shouldn't interfere with it either, and may have their own monitoring solution. Even if I choose not to go with more microinverters, I can always augment with a central inverter at that time, delaying my spending until I've actually have a need and the future options in front of me.

Were my combination of needs & priorities different, I could have easily ended up the SolarEdge. Clearly it's a good product. For me the biggest factors were really just preserving my wall space and having low-cost/low-commitment options should either my installer or the maker of my inverter disappear. Everything else contributes but that's what really tips the scale for me, and the situation will be different for other people. Also, in my case, the extended warranties for SolarEdge would have pushed the price higher than Enphase, and I really don't like buying extended warranties even when I'm 100% sure the company will be around to honor them (and I'll be in the house to benefit from it). Another case of going all-inclusive up front, or a la carte as you actually need it. Some folks will prefer one over the other. Just like some people are happier buying an oversized system relative to what they use right now vs saving on upfront costs.

[entgegnen]

Let me ask this of ButchDeal (or others who may have an opinion):

Earlier on this thread you mentioned that: "Of course SolarEdge would be cheaper than enphase and not have the clipping."

Currently, the contractor that I am considering has said that either system would cost me essentiality the same. I can get a SolarEdge with the extra warranty, so on and so forth, and do it for the same price as the Enphase....

Does this seem out of the ordinary to you? (given the comments that Solaredge is less costly? I was originally thinking that the extra labor cost and warranty pretty much got me to the same place..... or could it be he gets incentives from Enphase if he sells that product?)

[entgegnen]

If I may (using entgegnen's numbering)...

Basing the decision on 5 (clipping) is kind of silly. The other differences between the systems are much more significant. Many people who post in the forum do seem to develop an emotional response to clipping, no matter how many times it is demonstrated that the amount of energy lost is inconsequential.

On 6 - microinverters are more interchangeable, but they make it hard because most use a proprietary trunk cable to make the connections. You can build yourself an adapter, perhaps, but it wouldn't be an off-the-shelf kind of thing. You might also have to give up per-panel monitoring on the replacement micros; I'm not sure you can have two monitoring systems active at one. If you truly want interchangeable inverters, stick with a pure string inverter.

No, you are right - I'm sort of admitting the absurd psychological focus on clipping.... I figure by posting it here... maybe I can get it out of my system....!