Enphase M215 Still In the Box - Design Suggestions

[Ksnax]

I am looking for a little guidance on how I should utilize 19 new M215 inverters that I have purchased; specifically a scheme for easy access to replace them when necessary.

My plan is to install 19 300 Watt panels in addition to the 4.96kW SolarEdge system I have operating now. I am planning to do all of the work myself in what will essentially be two new separate systems of 1.2kW and 4.5kW. As I said, I already have the inverters, so I want to try to make best use of them - without discounting the need for potential replacements.

So being that these are an older generation of inverter, my thought is to use an alternate inverter scheme for the smaller string, providing me with 4 of the M215s as spares (which will hopefully be enough for the next 25 years - I know, we'll see). This leaves me with 15 inverters on the larger array on the roof of a shed I am building this spring. (The smaller array is going on an easily accessible awning with open access underneath.)

I probably won't live here long enough to see that many of them fail, but I don't want to make it hard on myself if one or more does. What sort of provisions should I plan for to make inverter replacement on the shed as easy as possible?

[Ksnax]

Oh, and a follow up: Am I being optimistic with planning to use 300W panels with these inverters?

I am prepared for the reality that output will be clipped during peak sun. Am I expecting too much out of the inverters over the long term by designing in clipping like that?

[J.P.M.]

Before I went further, I'd take a few minutes and investigate how much clipping will occur due to the 215/300 ratio, and what the value of the lost (clipped) generation might be.

[Ksnax]

Well the basis of my thinking on that comes from Enphase directly. I am most curious if this is simply going to be a case of overstressing the inverters that will lead to earlier failures.

https://enphase.com/sites/default/files/Enphase_White_Paper_Module_Rightsizing.pdf

[Ksnax]

I should also clarify that my decision to use 300W panels is strictly based on pricing and availability. If I can find lower rated panels at a lower cost per watt, I will use them.

[Pitter98]

I've been looking at using these same inverters due to their low cost right now and was looking at similar size panels (280 to 300 watt range) to go with them. Depending on your location and your sun angles, you will likely lose very little of your ouput. There was a thread I found a little while back that talked about clipping with the M215s, and the general consensus was it was under 5% of the total output. You would only be knocking out the very top few watts for a few hours a day during the best production seasons. According to PVWatts, for me in Michigan with a 270 degree orientation (not ideal) 300 watt panel, I would only losing a few hours of peak production a few days a week during the summer months only. If you are in a sunnier and warmer climate, you may lose more, but it would still only be a very small portion of your total output.

If you want to see it for your self, run PVWatts with all your relevant system info, then download the hourly results. Take your number of inverters and multiply by 225w (max output of the M215) and then compare that number with the peak hourly outputs from PVwatts. Whenever you exceed that number, it will be the lost production from clipping.

And as a side note, from what I have seen, by going with a larger panel and not worrying about the clipping, you will generally produce more power because it will raise your baseline production for the whole day while only losing the very peak for a couple hours a day.

Edit: Here is the study by Enphase (so take it with a grain of salt if you wish) that showed this:

https://enphase.com/sites/default/files/Enphase_White_Paper_Module_Rightsizing.pdf

[J.P.M.]

I should also clarify that my decision to use 300W panels is strictly based on pricing and availability. If I can find lower rated panels at a lower cost per watt, I will use them.

Understood. My suggestion was only based on how easy it is to get a SWAG on how much production might be lost from a relatively small microinverter/panel ratio, and how that might affect a design. A 250/300 W micro to panel ration might not clip at all or minimal. A 215/300 W ratio will probably clip more. How much ? Seems easy to get an estimate, may 5 minutes work or so. What's to lose in relation to the info/knowledge to be gained by the exercise ?

Maybe doesn't matter much when the $$/hassle of replacing one micro, or several, over time is considered.

[Ksnax]

I think I have decided on some 280W Trina panels from Alt-e. They work out to about 52 cents per watt shipped. Can't beat that price anywhere from what I have seen short of going with aliexpress and the questionable quality that might come with that.

No matter what, clipping is still lost production, but the cost to production ratio with that looks pretty unbeatable combined with what I paid for the M215s.

I have however decided to downsize the larger array for space reasons, so that will give me 3 extra inverters if I put what I have on both arrays. Not bad insurance for the money I think.

[sdold]

A friend and I bought and installed 26 M215s almost five years ago, so far none have failed, so I wouldn't lose sleep over it. I'm not hearing of M215 failures like we do with the older M190s. Instead of installing between the rails, I installed mine facing away from the rails, still under the edges of the panels, but where I could reach them without removing a panel. So far so good, no need to access them yet.

[Ksnax]

That's great to know!

I might have to just order 3 extra panels and 'find a place' for them at a later time. If I need to, I could probably unload them pretty easily with inverters locally later this year as the tax season and 30% credit comes to a close.

[Pitter98]

That's great to know!

I might have to just order 3 extra panels and 'find a place' for them at a later time. If I need to, I could probably unload them pretty easily with inverters locally later this year as the tax season and 30% credit comes to a close.

Actually, you've got until the end of 2021, just at a reduced rate.

https://www.solarreviews.com/blog/how-do-i-claim-the-federal-solar-tax-credit

[J.P.M.]

That's great to know!

I might have to just order 3 extra panels and 'find a place' for them at a later time. If I need to, I could probably unload them pretty easily with inverters locally later this year as the tax season and 30% credit comes to a close.

Word to the wise, I'm pretty sure the IRS code says the equipment must be placed in service the year the tax credit is taken. Just sayin'.

[Ampster]

Word to the wise, I'm pretty sure the IRS code says the equipment must be placed in service the year the tax credit is taken. Just sayin'.

So you are sayin that the future buyer of his panels and inverters would have to put them in service the same year that the future buyer bought them? How does that affect the OP?

[J.P.M.]

So you are sayin that the future buyer of his panels and inverters would have to put them in service the same year that the future buyer bought them? How does that affect the OP?

No, that's not what I'm saying at all. And it looks to me like you may be inferring more than I'm meaning or simply trying to be a PITA.

But, assuming your question is genuine, an answer: Some future buyer of the OP's equipment purchased by the OP in 2019 and probably/perhaps tax credited in 2019 was not and is not part any of my thinking when I wrote the post.

I wrote that post with the idea that a little head's up to the OP might be useful if, and perhaps, the OP, like most solar users it's been my experience to know/work with, is, has, or may be planning to take the 30 % tax credit on the full amount of material and labor for a solar installation. No other purpose than that.

Anyway, and a further point to your question, if the OP does sell excess equipment in the future, any such equipment might be considered used anyway and so ineligible for any fed. tax credit for any future buyer of such used equipment.



However, I must thank you for making me check my information. My prior statement to this thread with respect to the placed in service date requirements for U.S. federal tax credit eligibility was incorrect.

My apologies to the OP and other members/readers of that post.

Better information as best as I can read it:

As of last June 15, 2018, an IRS bulletin (Notice 2018-59) modified the date when equipment must be placed in service by to receive the full 30 % tax credit.

But, antecedent information is necessary: The placed in service date for solar projects must first be established. That date, according to the IRS, can be determined in one of two ways. One way is to actually start work according to IRS definitions. The second, which may be more applicable to the OP's situation, is when the person/entity intending to claim the tax credit has incurred 5% of the cost of the project, including equipment costs. Either method requires "continuous progress" toward project completion.

Specifically to my error: The June 2018 IRS ruling changes the latest allowable completion date for projects started in 2019 from 01/01/2020 TO 01/01/2024.

To be clear, the percentage of a project started after 12/31/2019 that is tax credit eligible still declines to 26 % for 2020 and declines further in following years. But projects started in 2019 according to the June 15 , 2018 IRS guidelines still qualify for the 30%, and once begun, have until 01/01/2024 to complete.

Back to the OP's situation on extra or excess equipment, I'm not sure how, nor is it clear to me from my reading of the above referenced bulletin, how the IRS, or anyone else for that matter, would consider or treat excess equipment for tax credit considerations.

I've done projects for plant and equipment where the budget and equipment lists and B/M's included a certain $$ amount and/or certain equipment as spares and replacement, and those things were considered part of the project scope.

I'm sure not the IRS, but I'd think a certain quantity of such items might reasonably considered as necessary part of a complete solar energy project, especially if certain such equipment was likely to be discontinued/replaced in the future and non-identical replacement would cause production or other system problems.

[Ksnax]

Thanks J.P.M. I'm not really concerned too much about the tax credit for excess equipment. The requirements are well understood however, and the rest of the system will be operational by mid-year.