Replace inverter? Need advice

[egizzi]

I have a 9 year old 3.3kw system on my roof installed by Borrego. The panels are 48 cell kyocera panels.

The inverter is a Sharp Sunvista JH-3500. It's a 3.5kw inverter.

The first inverter died right before the 5 year warranty expired. Sharp replaced it through the company Borrego had sold their residential service (I believe it was GroSolar). Now the second one has died a little over 4 years later.

The problem is that Sharp has no record of this second inverter and the solar company that replaced it can't find their paperwork either. Mea culpa that I did not get any paperwork when it was replaced.

I will call Sharp to press them directly about repairing/replacing this inverter for free. If they agree to do that, then that's the obvious choice.

If they refuse, then I have two options:

1) pay for Sharp to repair it
2) switch inverters, and go with a sunny boy inverter with a 10 year warranty

If I switch to a sunny boy inverter, I'm looking at their new ones (the 3800 and the 4000). I'm not sure why the 4000 is less expensive than the 3800. Am I correct that I simply need to get an inverter that exceeds the kw that my panels generate? I would go this route through one of the local solar shops that repair/install solar.

I am totally disappointed that my inverter has died again. When I went through the math to decide about solar, I did not calculate equipment failure. I can't change to micro-inverters because my panels are 48 cell. So I have to have a single grid-tie inverter, and I'm leaning towards the sunny boy just for peace of mind.

-Elio

[Ian S]

You might want to consider a smaller 3kW Sunny Boy instead. It should be cheaper and still easily able to handle a 9 y.o. 3.3 kW system which will have likely lost some of its power capacity anyway. Generally, it's OK to undersize a quality inverter like the SMA by 10%. The Sunny Boy TL models also offer a feature to provide some power during daylight when the grid is down.

[Volusiano]

Yeah, SMA has a website for their solar design tools called Sunny Design. You should go on there and input your panels and configurations, and select the 3K Sunny Boy to see if it will do the job adequately for you or not. Sometimes based on your pitch and orientation, you may not always get near name plate production output anyway. The active power ratio (PV Peak Power/AC Active Power) sometimes can be around 80% and it may still be OK, as long as your energy usability factor is near 100%, then you won't have too much clipping.

As to why the 4000 is less expensive than the 3800, you should probably pay attention to whether it's the new TL (Transformer-Less) or the old kind using conventional transformer. Maybe the difference between the 2 types can mean a price difference regardless of the size rating. I would recommend you go with the new TL design for a smaller, lighter and cooler (less heat) inverter.

I think SMA also has extended warranty options in case you want to get a 15 or 20 year warranty instead of 10.

[Mike90250]

you bought a inverter with a 5 year warranty, and got 4 out of it. After 1 more year, you have no more warranty left. (if they replaced it for free). Same way battery and tire warranties work.
Getting a reset on the warranty period is a freebie, if they offer it.

Looking for new inverters, TL (transformer less) inverters weigh a lot less then their wattage equivalent.

[egizzi]

you bought a inverter with a 5 year warranty, and got 4 out of it. After 1 more year, you have no more warranty left. (if they replaced it for free). Same way battery and tire warranties work.
Getting a reset on the warranty period is a freebie, if they offer it.

Looking for new inverters, TL (transformer less) inverters weigh a lot less then their wattage equivalent.

I agree with you, though the second inverter was brand new. I'm sure Sharp will say I don't get a reset on the warranty clock, but it's worth a try. It is pretty poor design/quality that two new units would not even make it out of their respective warranty period.

I'll go with a TL model. I have a couple of emails out to local solar maintenance shops and I'm asking them to run some numbers based on my system and see which sunny boy inverter is the right one.

Updates as we go along.

[Volusiano]

I'll go with a TL model. I have a couple of emails out to local solar maintenance shops and I'm asking them to run some numbers based on my system and see which sunny boy inverter is the right one.

That's one option, but the easier way is just to go online to the SMA Sunny Design web page and run the numbers yourself so you can see it for yourself. That's what your local shops will do anyway.

[inetdog]

That's one option, but the easier way is just to go online to the SMA Sunny Design web page and run the numbers yourself so you can see it for yourself. That's what your local shops will do anyway.

Elio, You have to register to use the tool set online, but it is free and does not require any other connection with SMA.

[egizzi]

Sunny Boy Design Site

I went to the sunny boy design site and started a project. Now I'm confused. When I enter my panels (Kyocera 167G, 24 of them), the system rates at 4kw. I don't know the azimuth, etc of the panel placement. When I review the original proposal, I'm sure they calculated some reduction in optimal power generation because of roof pitch, azimuth, the large tree that blocks the panels at times, etc. I am inferring then that the 3.5kw Sharp inverter they chose/installed was based on that reduction.

On the sunny boy design site, based on eyeball roof pitch of 32 degrees and southward facing (0 azimuth), the program says that the SMA 3000TL is too small. But they are not taking into account the specifics (ie the tree) that would reduce output, nor are they taking into account the panels are 11 years old.

So my question is what to do next. I hesitate to be the one to pick out the inverter for fear I'll pick the wrong one. I have an estimate from a local shot for the SMA 3000TL at around $1450 plus 4 hours to remove the dead inverter and put in the new one. But I did not ask them to do some calculations to pick the proper capacity inverter. Should I? And if so, is it reasonable to ask that they include that in the 4 hours?

[Volusiano]

I went to the sunny boy design site and started a project. Now I'm confused. When I enter my panels (Kyocera 167G, 24 of them), the system rates at 4kw. I don't know the azimuth, etc of the panel placement. When I review the original proposal, I'm sure they calculated some reduction in optimal power generation because of roof pitch, azimuth, the large tree that blocks the panels at times, etc. I am inferring then that the 3.5kw Sharp inverter they chose/installed was based on that reduction.

On the sunny boy design site, based on eyeball roof pitch of 32 degrees and southward facing (0 azimuth), the program says that the SMA 3000TL is too small. But they are not taking into account the specifics (ie the tree) that would reduce output, nor are they taking into account the panels are 11 years old.

So my question is what to do next. I hesitate to be the one to pick out the inverter for fear I'll pick the wrong one. I have an estimate from a local shot for the SMA 3000TL at around $1450 plus 4 hours to remove the dead inverter and put in the new one. But I did not ask them to do some calculations to pick the proper capacity inverter. Should I? And if so, is it reasonable to ask that they include that in the 4 hours?

The tool doesn't have knowledge of shading and assumes no shading issue in its production estimate, I think.

I tried the 24 Kyocera 167 with your azimuth and pitch on the 3KTL (but my location since I don't know yours) and it worked out just fine for me. Use 1 string of 12 for inputA and 1 string of 12 for inputB. It's not ideal because the inverter is a little under size (80% < 83% efficiency), so it's only conditionally compatible with 99.2% energy usability factor. If you bump it to the 3.8KTL or 4KTL, it would be better. But it's not severely under size, just slightly. The 99.2% energy usability factor is still not too bad.

I would ask the shop to see how much more to go for a 3.8KTL or 4KTL and decide whether you want to pay a little more for a bigger size inverter or not. If it's too much more money, ask the shop if the 3KTL is good enough in your case. After all, like you said, your panels are already 11 years old and you have some shading.

A reputable shop wouldn't just blindly install a new inverter for you without taking the 5-10 minutes to verify that the inverter is adequate for your configuration. It's reasonable to ask them to double check your selection for you and not charge you more than the 4 hours quoted already, because I will almost guarantee you that they'll just do the exact same thing you did -> go on the Sunny Design website and input your configuration to verify that your inverter of choice is acceptable for use. After all, they'll have to provide warranty for that inverter to you. If they blindly install the wrong size inverter, they're not going to be able to get the warranty honored by the manufacturer and they're still on the hook to honor the warranty to you because they're ultimately responsible for the inverter operating correctly as designed.

Is your current configuration already in 2 separate strings of 12?

[russ]

the large tree that blocks the panels at times, etc.

A major shade problem and using a string inverter? Something smells really bad here.

[Volusiano]

A major shade problem and using a string inverter? Something smells really bad here.

Since his system is 11 years old, maybe they only had string inverters back then and microinverters or SolarEdge type optimizers weren't around at that time?

Or maybe the tree grew big enough over the 11 years to start causing a shade problem?

[egizzi]

update

It's not a major shade problem. But there is a big Oak tree off to the side of the house that does shade. Microinverters were not possible 11 years ago for residential installations. Before my inverter died, my power production was good enough that my initial estimate of a break even point of 11 years was reached.

Here's the update from the solar company I've been emailing about the inverter replacement:

The TL models would technically string up OK. They have dual mppt’s and a much larger input band.

However your solar modules are not compatible with transformer-less inverters.

Our new recommendation, which comes via tech support of SMA suggestions, is the 3000 HFus inverter. Cost of the inverter are $1512 plus tax. Our 350 installation fee would remain. When I went to the sunny boy design site, I entered my exact brand of panels and picked the TL model of inverter and no error was mentioned.

Strings would be 2x12, so we would need to re-wire at the PV system. Additional cost TBD.

This is a little too technical for me, so I'm not sure what to say. The panels are Kyocera 167G, and they are arranged in a 4 x 6 grid which fits nicely on my dormer roof. Wisdom appreciated.

[Volusiano]

It's not a major shade problem. But there is a big Oak tree off to the side of the house that does shade. Microinverters were not possible 11 years ago for residential installations. Before my inverter died, my power production was good enough that my initial estimate of a break even point of 11 years was reached.

Here's the update from the solar company I've been emailing about the inverter replacement:

The TL models would technically string up OK. They have dual mppt’s and a much larger input band.

However your solar modules are not compatible with transformer-less inverters.

Our new recommendation, which comes via tech support of SMA suggestions, is the 3000 HFus inverter. Cost of the inverter are $1512 plus tax. Our 350 installation fee would remain. When I went to the sunny boy design site, I entered my exact brand of panels and picked the TL model of inverter and no error was mentioned.

Strings would be 2x12, so we would need to re-wire at the PV system. Additional cost TBD.

This is a little too technical for me, so I'm not sure what to say. The panels are Kyocera 167G, and they are arranged in a 4 x 6 grid which fits nicely on my dormer roof. Wisdom appreciated.

I read somewhere that the TL needs the panels to be earthed, but the HF doesn't (because the HF has galvanic isolation). It's a safety issue I guess. So maybe your panels were not earthed 11 years ago (code didn't require back then?), so now rather than earthing the panels, which is more troublesome and more expensive, they want to go with the HF to avoid having to earth the panels. The galvanic isolation of the HF will let them not have to earth the panels.

The Sunny Boy design website said the 3KTL was OK for your panels because it probably assumed a new installation with earthed panels.

This is just my guess. It may benefit you to confirm whether this is the real reason they don't want to go with the TL but want the HF instead. You can ask either your installer or call SMA technical support and ask them directly.

I don't know about your system, but my recently installed system last year has a bare ground wire going into the 2 inverters I have. Maybe this is a tell tale sign that my panels are earthed which allows me to use the 4KTL. If you don't see any bare ground wiring going into your current inverter, that may be an indication that your panels are not earthed???

[Naptown]

I read somewhere that the TL needs the panels to be earthed, but the HF doesn't (because the HF has galvanic isolation). It's a safety issue I guess. So maybe your panels were not earthed 11 years ago (code didn't require back then?), so now rather than earthing the panels, which is more troublesome and more expensive, they want to go with the HF to avoid having to earth the panels. The galvanic isolation of the HF will let them not have to earth the panels.

The Sunny Boy design website said the 3KTL was OK for your panels because it probably assumed a new installation with earthed panels.

This is just my guess. It may benefit you to confirm whether this is the real reason they don't want to go with the TL but want the HF instead. You can ask either your installer or call SMA technical support and ask them directly.

I don't know about your system, but my recently installed system last year has a bare ground wire going into the 2 inverters I have. Maybe this is a tell tale sign that my panels are earthed which allows me to use the 4KTL. If you don't see any bare ground wiring going into your current inverter, that may be an indication that your panels are not earthed???

Actually that is incorrect
The tl series are not grounded on one side of the DC. (either positive or negative) the array floats.
Please try to refrain from giving technical advise unless you are absolutely sure it is correct.

[Volusiano]

Actually that is incorrect
The tl series are not grounded on one side of the DC. (either positive or negative) the array floats.
Please try to refrain from giving technical advise unless you are absolutely sure it is correct.

First of all, thanks for the clarification, Rich. It's always good to have knowledgeable installers on the forum to clarify and correct things.

Having said that, I believe that I put enough qualifications in my post to make it clear that I'm not absolutely sure of anything. In my post, I said "I read somewhere" and a lot of "maybes" and "This is only my guess". Just throwing out some possibilities based on what I read. Whether the info is right or wrong, I don't really know for sure. Just passing along info.

The only technical advise I gave the poster in my post is to check with his installer or SMA technical support to find out why they can't use the TL and must use the HF.