New solar install, wrong microinverters used

[jmdenver]

Ok, got a new system installed yesterday. Per contract and all engineering/county permit paperwork was to have received 17 Hoymiles HM-350NT microinverters. (One per VSUN410-132BMH panel.)

Once they had finished and left I got my credentials from them for the Hoymiles app. I looked at the device list and saw that they installed 4 Hoymiles HM-1500NT (four panels each) and one 350NT for the 17th panel. I brought it to their attention earlier today just asking why they did that and what they propose as a resolution but have not received a reply as yet.

Aside from being dishonest and not at all in accordance with the paperwork they submitted for the permits (and presumably to my power company) how much of a fuss should I raise over this? Should I ask for a discount, insist they re-do it and/or (assuming they refuse) get quotes from other installers to correct and deduct from my payment, etc. I'd imagine the work involved with removing all the panels, buying the proper inverters, installing them and redoing all the wiring would be multiple thousands of dollars. (all they have so far is a 10% deposit)

Theoretically what they installed should actually have a slightly higher AC capacity. The contract and all paperwork list 5.93kW DC - all based on 17 350NT inverters - and oddly that's exactly what the Hoymiles app says despite the 4 1500s and 1 350 theoretically coming closer to 6.3kW.

I do know that should one of the 1500NTs fail I will lose production from 4 panels - ~25% of total generation - as opposed to ~6% should one of the intended 350NTs fail. That alone is a big downgrade. Beyond that are there any other reasons these 4 in 1 inverters are inferior to 1 per panel?

Other worries are electrical/wiring compliance/safety. Since the county approved this based on the 350NTs I have doubts that, since they used entirely different equipment, it was done safely or adequately. The inspector for the electrical was out yesterday and apparently passed it but he spent a mere 45 seconds on the roof and with the panels already installed he couldn't exactly count the inverters. I imagine he just assumed the design plans were what was installed and made sure the new electrical subpanel/disconnect on the outside wall and the inside panel looked right.

It is still pending the "building inspection" and whatever it is the power company looks at when they come out - I'd think it would fail the building inspection as it deviated so significantly from the approved plans but who knows. That inspector might just assume they installed what they were supposed to.

Ditto for the Hoymiles warranty. Their site implies to get warranty coverage (exchange/replacement) you need a detailed purchase receipt and design specs/diagrams. As mentioned there is zero paperwork that makes mention of the 1500NTs so they would certainly deny coverage based on no record of those being contracted for or submitted for permits/approvals.

Unfortunately the same people also installed my roof (I have no complaints on that) and most of their "lifetime labor/workmanship" warranties for both the roof and solar are well beyond what the manufacturer provides - so in that regard they kind of have me over a barrel since the more annoyed I make them the less likely they will ever actually meet those warranties,

 

[Bluedog225]

@ncsolarelectric will know.

Have you paid yet?

Personally, I’d require adherence to the terms.

 

[timselectric]

Should I ask for a discount

Absolutely
It's cheaper the way they done it.

Beyond that are there any other reasons these 4 in 1 inverters are inferior to 1 per panel?

No

That inspector might just assume they installed what they were supposed to.

More than likely.

Unfortunately the same people also installed my roof (I have no complaints on that) and most of their "lifetime labor/workmanship" warranties for both the roof and solar are well beyond what the manufacturer provides - so in that regard they kind of have me over a barrel since the more annoyed I make them the less likely they will ever actually meet those warranties,

Very true

 

[jmdenver]

@ncsolarelectric will know.

Have you paid yet?

Personally, I’d require adherence to the terms.

No, haven't paid (beyond the 10% deposit) Here is their nonsensical response:

"Hoymiles builds their micro-inverter system around 3 units that are used interchangeably based on the layout of the panels. Whether it is a 1-1, 2-1, or a 4-1 unit each panel has it's own inverter inside the casing working independently to convert the power from the panel it is connected to. While the 1-1 and 2-1 peak at 350w per panel the 4-1 peak at 375w. The more 4-1s we can use the more power that can be converted per panel on the high end. This is above and beyond what was quoted. We build our quotes on what we can guarantee no matter the layout and then we utilize the best equipment for production when we do the install. This is an added benefit to our customers.

Hoymiles setup is a less expensive option than something like Enphase that only provides 1-1 inverters. This is reflected in the price of our bid. To do your same system with an Enphase product would be $2,021.3 more."

 

[fromport]

So instead of 17 x $208.25 = $3540.25
they installed 4 x $505.75 = $2023 + $208.25 = $2231.25
Plus less mounting materials, less hours on the roof.
All of that is in _their_ favor, not yours and they did it without notifying you.
I think you should have a more thorough talk with them.

 

[jmdenver]

View attachment 208816
So instead of 17 x $208.25 = $3540.25
they installed 4 x $505.75 = $2023 + $208.25 = $2231.25
Plus less mounting materials, less hours on the roof.
All of that is in _their_ favor, not yours and they did it without notifying you.
I think you should have a more thorough talk with them.

Let me ask this.. as they are saying oh this is actually better because the 1500s have a max 375w per panel whereas the 350 is, well, max 350 why does Hoymile state the exact same 5.93 kW AC as the pernit plans stated with entirely different equipment? Is the entire system limited by the lowest "performing" micro inverter, in this case the single 350 - ie are the 1500s that should put me around 6.3kW being limited to 350w per panel also?

 

[fromport]

Let me ask this.. as they are saying oh this is actually better because the 1500s have a max 375w per panel whereas the 350 is, well, max 350 why does Hoymile state the exact same 5.93 kW AC as the pernit plans stated with entirely different equipment?

Original setup: 17 x 350 = 5,950 watt AC
modified setup: 4 x 1500 + 375 = 6375 watt AC
Afaik most inverters (string or micro) can do a little bit over their rated specs.
Some of them are software limited (eg Sunnyboy/fronius 3.8kW units to not go over the 16 amps (80% of a 20 amp breaker)) for wire/breaker protection.

I see with my Enphase micros up to 20% if there are cooler temps and bright sun. That helps both panels and inverters.
I wouldn't be surprised if the actual electronics in the 1500 watt model are 4 of the 350 watt model.

DC/AC ratio:
410 watt panels on a 350 watt inverter = 1.1714 ratio. I think up to 1.25 is acceptable but some people say up to 1.35 is acceptable.
The change your panel is going make the inverter clip is only a few days out of the year.
If the 1500 model would give you 7% more AC capability per panel, even over 10 years, the extra value in money is probably below $50 for you.
It would be in your favor, for sure, but they are collecting thousands of dollars one time during the install while you gain max $50 over 10+ years.

They are taking a (profit) shortcut.
If they would have talked with you about it, and may split a percentage of the savings with you, that would have been nice.
Now... not so..

Is the entire system limited by the lowest "performing" micro inverter, in this case the single 350 - ie are the 1500s that should put me around 6.3kW being limited to 350w per panel also?

Only the manufacturer or experienced installer could tell you.
I have no experience with Hoymiles, but other members on this forum do, maybe they can share that info with us.

 

[zanydroid]

Context: I have one turnkey HM800 install and one DIY HM1500/HM700/HM350 mixed install that I had done after so I’m quite familiar with the equipment.

Counterfactual: suppose they properly designed with HM1500’s. Would you have accepted the contract?

In any case you should probably get the POCO and AHJ paperwork updated. Where are you located? There is a tradeoff in that you might poke the hornet’s nest, so maybe accept the higher output potential.

I do know that should one of the 1500NTs fail I will lose production from 4 panels - ~25% of total generation - as opposed to ~6% should one of the intended 350NTs fail. That alone is a big downgrade. Beyond that are there any other reasons these 4 in 1 inverters are inferior to 1 per panel?

With 1500s have a lower overpaneling ratio so higher production potential on days you would otherwise be clipped

On my personal system I would rather be efficient on hardware and dollars than hunt for maximum fault tolerance. People accept single string inverters (I would prefer two personally); 25% sized fault domain is great.

Granted I passed the savings in dollars and my time on the roof onto myself as a DIYer

Other worries are electrical/wiring compliance/safety. Since the county approved this based on the 350NTs I have doubts that, since they used entirely different equipment, it was done safely or adequately.

1500 and 350 plug into a trunk cable exactly the same way.

The main determining factor is whether they exceeded the maximum current allowed per branch on Hoymiles. The main way to check this is based on the plans as submitted

response:

"Hoymiles builds their micro-inverter system around 3 units that are used interchangeably based on the layout of the panels.

This is mostly right, however the HM-1500 are 2 MPPT/4 port design. So in some quite rare shading conditions it will be less optimal than a 1 MPPT per port design.

There are some theoretical power topologies where a 4 port 1500W inverter might beat 4 single port ones, if one panel is shaded while the other ones were clipped. Not really worth spending a lot of time thinking about except as a pedagogical aid.

I have a ton of shading at my house and I didn’t mind the shared MPPT since the two panels are paralleled first. Check forum search for how many people like parallel wiring, it’s popular.

Is the entire system limited by the lowest "performing" micro inverter, in this case the single 350 - ie are the 1500s that should put me around 6.3kW being limited to 350w per panel also?

? That doesn’t make electrical sense. They are not limited. Every microinverter is paralleled together on the AC side. There is no interaction between panels on different microinverters.

 

[zanydroid]

Hoymiles 1:1 microinverters have minimal, if any, cost savings over Enphase. In fact the trunk cable is probably harder to use

 

[zanydroid]

That helps both panels and inverters.
I wouldn't be surprised if the actual electronics in the 1500 watt model are 4 of the 350 watt model.

It is not identical, see my post about the MPPT topology.

6400/240=26.6A which exceeds what Hoymiles allows in one trunk.

How many solar breakers do the trunks land in? If it’s one they must come back and correct.

 

[zanydroid]

I checked your drawings. Assuming they distributed 2x 1500 on one and 2x 1500 and one 350 on the other. Worst case is (3350/240) = 13.95A.

On a 20A branch the limit is 16A. Plenty of headroom

Note: I should be doing this looking at the spec sheet instead of using the model numbers but the headroom is big enough that exact electrical specs don’t matter.

 

[zanydroid]

why does Hoymile state the exact same 5.93 kW AC as the pernit plans stated with entirely different equipment?

I think you manually enter that size as an installer when you set up a customer system. It is not auto calculated. I will check on my installer app.

EDIT: yep, free text field. Click attachment to expand

 

[jmdenver]

Counterfactual: suppose they properly designed with HM1500’s. Would you have accepted the contract?

That's hard to answer at this point. Had they once mentioned it I would have had a chance to do some research and balance the potential loss of 4 panels on failure vs. asking for a lower price. With no price difference absolutely not.

In any case you should probably get the POCO and AHJ paperwork updated. Where are you located? There is a tradeoff in that you might poke the hornet’s nest, so maybe accept the higher output potential.

Yes, this has me freaked out. Can you even get a new/revised permit for something that has already been installed? Installed not in accordance with the original permit at that. As for the POCO I'm extremely hesitant to revise/reapply with them since they approved a significantly larger system than their calculations typically allow for. (no idea why it is there business but it's some complicated formula that I guess assures you are always going to be beholden to them. They may well not approve it this time. (And then where am I? I might have multiple panels that can't be used at all.) And as someone mentioned there is a concern with insurance / warranty / power company all denying claims or pulling my ability to use solar altogether since the current plans/permits don't match what was installed. (the power company explicity states : "Please be aware that if your equipment or installation design plans change from what we have approved, you must resubmit a revised net metering application including the new design and specifications for our review and approval. " And again I don't think they had in mind to do that AFTER installation.

I'm in St. Louis, MO. Zero shading with 13 panels facing south and 4 east.

? That doesn’t make electrical sense. They are not limited. Every microinverter is paralleled together on the AC side. There is no interaction between panels on different microinverters.

Was just looking for some possible reason the Hoymiles app is reporting 5.93kW when the 1500s + 1 350 should have me at 6.35. It clearly knows that I have 4 1500s and 1 350.. but that's the least of my concerns.

 

[Hedges]

If they installed other that what the contract says, and it was cheaper hardware, they owe you at the very least the difference in hardware costs. Probably also the labor costs, but unless you find a quote from them for the actual unit installed, won't know what that is.

Unless the fine print allows such substitution/optimization. Read it cover to cover.

 

[jmdenver]

I think you manually enter that size as an installer when you set up a customer system. It is not auto calculated. I will check on my installer app.

EDIT: yep, free text field. Click attachment to expand

Thanks! Ok, I guess the installer just read it off the permit. (too bad he didn't actually pay attention to the fact the installation he did bore no resemblance to the permit lol) But that is one bonus for the way they did it. BUT will require all new permits/POCO submissions. They are bugging me now to sign something for the POCO. I really can't in good conscience knowing (well I never saw what they submitted to them but it was the first thing they did so undoubtedly it is the 17 microinverter plan) it isn't a valid design approval.

 

[jmdenver]

If they installed other that what the contract says, and it was cheaper hardware, they owe you at the very least the difference in hardware costs. Probably also the labor costs, but unless you find a quote from them for the actual unit installed, won't know what that is.

Unless the fine print allows such substitution/optimization. Read it cover to cover.

No, it just says WITH MY CONSENT they can change the "modules" (which is very well defined elsewhere as the panels themselves) if there are supply issues and they will still provide the contracted wattage. Says nothing whatever about the microinverters. And yes I'd need at least that difference plus new permits, etc. (I fully expect them to have numerous excuses about how revised permits / POCO design review aren't necessary, not to mention even agreeing to pay what they saved when they arbitrarily switched. Just out of principal I want to gouge them lol but as things stand this will already get pushed back another two months at this point.

 

[zanydroid]

At this point you may need advice from an independent installer in that works with your POCO. Someone like me on the forum would have to spend a lot of energy to parse the pros/cons and not have all the necessary experience/info anyway...

That's hard to answer at this point. Had they once mentioned it I would have had a chance to do some research and balance the potential loss of 4 panels on failure vs. asking for a lower price. With no price difference absolutely not.

How much was the cost relative to the IQ8A quotes that you got?

The main thing you have against contractor in arbitration (whether by state licensing board or mandatory arbitration) is the reduced fault tolerance. That performance specification may not be included in your contract / covered by contractual language saying they can substitute.

Yes, this has me freaked out. Can you even get a new/revised permit for something that has already been installed? Installed not in accordance with the original permit at that.

I'm sure this happens all the time.

An issue is that the city will then stamp the updated plans. And when you send the stamped plans to POCO they have another chance to detect the discrepancy.

If you inform the city they may be willing to cancel the inspection pass.

As for the POCO I'm extremely hesitant to revise/reapply with them since they approved a significantly larger system than their calculations typically allow for. (no idea why it is there business but it's some complicated formula that I guess assures you are always going to be beholden to them. They may well not approve it this time. (And then where am I? I might have multiple panels that can't be used at all.)

Presumably the contractor can eat the cost to take it back.

Another option is to request Hoymiles export limiter be installed (probably rare in the US) to cap it at what your POCO allows.

The POCO has a chance of detecting the +5% output on high production days.

And as someone mentioned there is a concern with insurance / warranty / power company all denying claims or pulling my ability to use solar altogether since the current plans/permits don't match what was installed.

These are microinverters of the same safety level / product family as on the specs, and they meet the manufacturer instructions.

 

[zanydroid]

I personally think it was mis-spec'd (or their outsourced draftsperson did the wrong thing) as single ports instead of the proper Hoymiles design.

ncsolarelectric has his HM350 at $173, and CurrentConnected has the equivalent IQ8A at $192. Q cables are cheaper per drop than HM trunk + cable combos, so it's less than $10-20 delta per panel. Probably a lot of people would just go with IQ8A at that point.

EDIT: You're probably within your right to make a big fuss about it. Main downside I can see is if you accidentally slipped above the allowed solar size with your POCO, and making this fuss actually gives you a smaller system.

As well you might end up paying +$2K if they take their hardware back and you go with an IQ8A quote. And you end up with patched holes on the roof (which they may just send their own crew to do to save $), or if you leave the rails w/o patching and no other installer is willing to take the chance of reusing those.

 

[fromport]

It is not identical, see my post about the MPPT topology.

Thanks for enlightening me ! TIL.

 

[jmdenver]

I personally think it was mis-spec'd (or their outsourced draftsperson did the wrong thing) as single ports instead of the proper Hoymiles design.

Is 4:1 a "proper" Hoymiles design? I mean I can live with it I'm just very concerned about future headaches with warranty/insurance/POCO and aggravated that they willy nilly changed things up without saying "boo" about it and then just make up excuses (maybe they are legit, aside from the glaring fact it saved them money) and take no ownership/responsibility for it.

As well you might end up paying +$2K if they take their hardware back and you go with an IQ8A quote. And you end up with patched holes on the roof (which they may just send their own crew to do to save $), or if you leave the rails w/o patching and no other installer is willing to take the chance of reusing those.

I definitely want to avoid any more screwing around on my roof. I got a new roof solely for the purpose of getting solar (the old one probably had 5-10 years left on it) and certainly don't want to have more holes drilled / filled / then re-drilled.