About to install LG300A1C-B3 300W AC microinverters, got some Q's

[inetdog]

Hey thejq,

you have the DC 300w LG panel and per your graphic and your SE link, you seem to be getting on average peak about 265-270W per panel. Your system is real new and I know you dont get 100% efficiency, but did you expect to see a bit better results? a 4.8KW system and your site shows about 3.6-4.0 produced a lot. Is this average? Is the 10% loss on the panel bumped up to 15-17% by the time it goes through the inverter , seem average? Is it feasible that with the LG panels with the LG designed microinverters, that this inherent/expected inefficiency be reduced?

Your 28-30kWh you produced on avg or so, what you expected out of the 16 panels?

This is just my ignorance talking really, I have no idea.

Ignorance asking questions is a lot better than ignorance trying to ask them, so you are on the right track.

Because of the difference in real life panel temperature from STC panel temperature, as well as other issues of orientation, atmospheric conditions, etc, panels will rarely produce their rated output. On a cold day, at an elevation of 5000', and with just the right scattering of clouds outside the direct path toward the sun you can get 10% or more above the rated output.

The sizing tools and recommendations for microinverters take this into account and recommend that your panel produce more than the inverter rating, up to some limit.
Then even when the conditions are ideal and the panel overproduces you will only lose some power at solar noon but make up for it the rest of the day compared to a panel which never exceeds the inverter input limit. (Referred to as "clipping".)

And yes, 10% less than rated is not unreasonable for a hot day. Worse if there is not enough air space between panels and roof for proper cooling (4" minimum, 6" better). Then the efficiency of the micro will be somewhere between 90% and 95%, depending on the brand and who you believe.

[AaronG]

Hey thejq,

you have the DC 300w LG panel and per your graphic and your SE link, you seem to be getting on average peak about 265-270W per panel. Your system is real new and I know you dont get 100% efficiency, but did you expect to see a bit better results? a 4.8KW system and your site shows about 3.6-4.0 produced a lot. Is this average? Is the 10% loss on the panel bumped up to 15-17% by the time it goes through the inverter , seem average? Is it feasible that with the LG panels with the LG designed microinverters, that this inherent/expected inefficiency be reduced?

Your 28-30kWh you produced on avg or so, what you expected out of the 16 panels?

This is just my ignorance talking really, I have no idea.

[AaronG]

IANATL either, but from what I have read the cost of reinforcing the roof structure to take the weight of the panels and racking can definitely be included in the cost for tax credit purposes. The cost of putting on a new roof so that you will not have to take the panels off to reroof before the 20 year lifetime is up, even though your current roof has 10 years of life left, probably not subject to tax credit. Replacing your roof because it needs it right now anyway, definitely not creditable.

My roof is now 22 years old. I brought this up and they state that my roof should be in fine state and since the tiles are concrete that it should continue to last a lot longer. I worried about this, but I guess it is one of those things that since you've never had a leak or issue, its tough to replace the whole thing when it works well.

But yes item for discussion relating to the tax credit. Thanks.

[thejq]

IANATL either, but from what I have read the cost of reinforcing the roof structure to take the weight of the panels and racking can definitely be included in the cost for tax credit purposes. The cost of putting on a new roof so that you will not have to take the panels off to reroof before the 20 year lifetime is up, even though your current roof has 10 years of life left, probably not subject to tax credit. Replacing your roof because it needs it right now anyway, definitely not creditable.

I'm almost certain I was right regarding roof.

http://www.gpo.gov/fdsys/pkg/USCODE-2011-title26/pdf/USCODE-2011-title26-subtitleA-chap1-subchapA-partIV-subpartA-sec25D.pdf

Page 94, under solar panels, the text explicitly excluded roof, because it's part of the structural component.

[inetdog]

You're in a grey area here. Since I'm not a CPA nor tax lawyer, I can only speak from my own understanding FWIW. Upgrading the breaker panel is not strictly part of the solar installation. What is included is all the connection from the solar panel all the way to the power bus. So one extra breaker is ok. The same thing applies to the roof. For example, if you have to reinforce the roof to support the extra weight and wind factor, that cost is not included. What a lot of installers do to get around that is to charge more on the solar installation and almost zero on the panel upgrade. Because the upgrade is relatively small compare to the total cost, the increase is hardly noticeable. But if you do them separately and still claim the upgrade for tax rebate, it will be hard to explain if the IRS comes knocking. Just make sure you don't make it too obvious. Someone on this forum was given the choice to include the cost of AC in the solar installation. That maybe too obvious in my opinion.

IANATL either, but from what I have read the cost of reinforcing the roof structure to take the weight of the panels and racking can definitely be included in the cost for tax credit purposes. The cost of putting on a new roof so that you will not have to take the panels off to reroof before the 20 year lifetime is up, even though your current roof has 10 years of life left, probably not subject to tax credit. Replacing your roof because it needs it right now anyway, definitely not creditable.

[thejq]

One policy we always used in industry - never be an early adopter unless there was a very good reason - here there is no reason at all.

Very true, but for this reason, there might be deals to be had, since LG has to push it harder so early adopters will bite.

[russ]

So I can get that with the LG AC panel, or the LG DC panel with SE optimizers and inverter. At lest one of them is a proven product.

One negative with the microinverters is that no matter what LG is not *currently* offering more than 12 year warranty on them. They are aware that Enphase and others offer 20 or 25, but LG isnt yet. It is nutz to go for the new one with less warranty

Does it mean I would be grandfathered? Hah! Zero idea. No way they would do that - unless it is totally unneeded

I did decide to move the thermal and will have the original folks come out, measure where to move it and then pay them to move it. It sucks, but life goes on.

:EDIT: I read this on the LG spec sheet -- I cant speak for if it is real good, or just mediocre. The spec sheet is meaningless as far as to projecting what will happen.

One policy we always used in industry - never be an eraly adopter unless there was a very good reason - here there is no reason at all.

The induvidual panel monitoring is really only useful in that it allows you to have a "you show me yours and I'll show you mine" party. Trouble shooting is the supplier's or repairman's problem.

[AaronG]

You're in a grey area here. Since I'm not a CPA nor tax lawyer, I can only speak from my own understanding FWIW. Upgrading the breaker panel is not strictly part of the solar installation. What is included is all the connection from the solar panel all the way to the power bus. So one extra breaker is ok. The same thing applies to the roof. For example, if you have to reinforce the roof to support the extra weight and wind factor, that cost is not included. What a lot of installers do to get around that is to charge more on the solar installation and almost zero on the panel upgrade. Because the upgrade is relatively small compare to the total cost, the increase is hardly noticeable. But if you do them separately and still claim the upgrade for tax rebate, it will be hard to explain if the IRS comes knocking. Just make sure you don't make it too obvious. Someone on this forum was given the choice to include the cost of AC in the solar installation. That maybe too obvious in my opinion.

I agree. I'm just going to let this one go. At most I could save a couple hundred bucks, and it isnt worth my hassle.
It isnt at all worth the risk with the IRS n all either. No thanks.

I did talk to the owner of the company today about the LG AC vs. DC panel thing. He said he has had meetings with LG recently to talk about this panel and they are stoked to bring it to market. They really think this is going to be a huge hit for them. He also is comfortable/confident selling Solar Edge (they said they install 2-4 of these a month alone), but only time will tell if Solar Edge will be around 10 or 20 years from now, but there is little doubt that LG will still be in business. Even though I dont NEED micro inverters on that SW facing side or NEED optimizers, I definitely wanted the per panel monitoring so I am going one or the other. So I can get that with the LG AC panel, or the LG DC panel with SE optimizers and inverter. I've seen the links posted up here for looking at others SE systems and thats cool. What I dont know yet is what the LG monitoring solution looks like. For all I know it is not up to snuff. It sounds hard to compete though. So I am going to look in to that tomorrow.

One negative with the microinverters is that no matter what LG is not *currently* offering more than 12 year warranty on them. They are aware that Enphase and others offer 20 or 25, but LG isnt yet. I can get a string inverter with 20 year warranty at no extra charge. Will I be upset 13 years from now if I have issues with micro inverters? That soon? Probably! Is it possible LG will up their warranty terms? Sure. Does it mean I would be grandfathered? Hah! Zero idea.

I did decide to move the thermal and will have the original folks come out, measure where to move it and then pay them to move it. It sucks, but life goes on.

:EDIT: I read this on the LG spec sheet -- I cant speak for if it is real good, or just mediocre.
Monitoring Anywhere: LG provides advanced Web-based solution and stable environment with in-house server operation. Uers can monitor power generation through the Internet, anywhere and anytime.

[thejq]

I had a finance question some of you may or may not know, it's ok...

I need to upgrade my panel from the 100A to 125A. The solar company says if I do it through them then I can claim the 30% tax credit from the feds. Their price is high on the panel, but priced well AFTER the credit.

Is there any reason I cannot find an electrician who can do the work and their price is far less, but I can ALSO claim that 30% on the panel next year? Or must it be on the same work order as the solar installation themselves? What if the electric company that does the panel upgrade actually is licensed to do solar and does solar actively (but just not my home)?

You're in a grey area here. Since I'm not a CPA nor tax lawyer, I can only speak from my own understanding FWIW. Upgrading the breaker panel is not strictly part of the solar installation. What is included is all the connection from the solar panel all the way to the power bus. So one extra breaker is ok. The same thing applies to the roof. For example, if you have to reinforce the roof to support the extra weight and wind factor, that cost is not included. What a lot of installers do to get around that is to charge more on the solar installation and almost zero on the panel upgrade. Because the upgrade is relatively small compare to the total cost, the increase is hardly noticeable. But if you do them separately and still claim the upgrade for tax rebate, it will be hard to explain if the IRS comes knocking. Just make sure you don't make it too obvious. Someone on this forum was given the choice to include the cost of AC in the solar installation. That maybe too obvious in my opinion.

[AaronG]

I had a finance question some of you may or may not know, it's ok...

I need to upgrade my panel from the 100A to 125A. The solar company says if I do it through them then I can claim the 30% tax credit from the feds. Their price is high on the panel, but priced well AFTER the credit.

Is there any reason I cannot find an electrician who can do the work and their price is far less, but I can ALSO claim that 30% on the panel next year? Or must it be on the same work order as the solar installation themselves? What if the electric company that does the panel upgrade actually is licensed to do solar and does solar actively (but just not my home)?

[AaronG]

Per panel monitoring is the geek's view of system performance. It can be used to spot single panel failure more easily. I've attached a screen capture of my layout view.[ATTACH=CONFIG]4810[/ATTACH] Is it cool to look at? Yes, of course. Is it useful? It depends. For reliable panels which almost never fail, it may not be. I got it because for my system size the price of SMA and SE were almost the same. Plus I want to leave myself the choice to add panels if I have to. The panel level monitoring was icing on the cake.

Depending on where you live in San Macros, we could be within 10 miles of each other. My panels are facing exactly SW (230 az.). So far the system has been working great and better than expected.

Yeah that seems like a benefit, I like that screenshot and I would love to be able to see the per panel information. I'll ask for them. They should not cost extra to me, as the bid they competed against (that I didnt choose) included them.

[thejq]

Per panel monitoring is the geek's view of system performance. It can be used to spot single panel failure more easily. I've attached a screen capture of my layout view.Capture.JPG Is it cool to look at? Yes, of course. Is it useful? It depends. For reliable panels which almost never fail, it may not be. I got it because for my system size the price of SMA and SE were almost the same. Plus I want to leave myself the choice to add panels if I have to. The panel level monitoring was icing on the cake.

Depending on where you live in San Macros, we could be within 10 miles of each other. My panels are facing exactly SW (230 az.). So far the system has been working great and better than expected.

[inetdog]

Yeah it came in at 9500 or so...

So a question I have is that if I was installing on SW where there is zero shade. If I ask them to install optimizer is there any negative to having them, even though technically since there is no shade, I cant think of why they are needed other than to give me individual solar panel visibility in the management tool?

If, for example, one of the panels went bad (mechanical damage, birds nest, whatever) the SE system would not only show you that something was wrong and where, it would be able to make the best use of the remaining panels in the string, without having to rely on bypass diodes, etc.

[AaronG]

Suggest running your own production est. w/ the new PVWatts and use a 16% system losses and look for something like ~~ 9,000 - 10,000 kWh/yr. on 6,300 Watts of LG 300 panels. facing sort of SW at 20 deg. tilt.

Yeah it came in at 9500 or so...

So a question I have is that if I was installing on SW where there is zero shade. If I ask them to install optimizer is there any negative to having them, even though technically since there is no shade, I cant think of why they are needed other than to give me individual solar panel visibility in the management tool?

[J.P.M.]

He doesnt deal with money, but he figured there is almost no benefit from using power optimizers on my SW side which sees zero shade. However, if per panel monitoring is nice, I could ask for the optimizers. The original quote from the one company with DC panels and SE optimizers for the NE side included that. Any negative to installing them on my SW side? It's just 1 more component that I guess COULD go bad, right? But thats what warranty is for? hah


He said it will take 2-3 days to build the engineering plans, but by end of tonight he will have me the power production information, which helps me with my decision

Suggest running your own production est. w/ the new PVWatts and use a 16% system losses and look for something like ~~ 9,000 - 10,000 kWh/yr. on 6,300 Watts of LG 300 panels. facing sort of SW at 20 deg. tilt.