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GoingGreener

Well-known member
Joined
Jul 10, 2011
Messages
171
Location
SF Bay Area
We have a small solar array that's almost 4 yrs. old. Charging the LEAF at home brings us back up to the higher PG&E electric rate tiers. Our electricity bill has been about $60-$70/month more than pre-LEAF. Some of the increased costs could also be attributed to changes in other household electrical use too. We have driven the LEAF about 9,000 miles annually. 3 more Sunpower SPR-230 panels can be added with the current inverter we have.

Would it make sense to do that (Cost/efficiency degradation of current panels, etc...)? Would permits need to be obtained again? Or better to add another separate/new efficient system? If I remember correctly, the next scheduled activity would be replacing the inverter in about 6yrs? What, if any local and federal incentives can help this time around?

Thanks!
 
GoingGreener said:
We have a small solar array that's almost 4 yrs. old. Charging the LEAF at home brings us back up to the higher PG&E electric rate tiers. Our electricity bill has been about $60-$70/month more than pre-LEAF. Some of the increased costs could also be attributed to changes in other household electrical use too. We have driven the LEAF about 9,000 miles annually. 3 more Sunpower SPR-230 panels can be added with the current inverter we have.

Would it make sense to do that (Cost/efficiency degradation of current panels, etc...)? Would permits need to be obtained again? Or better to add another separate/new efficient system? If I remember correctly, the next scheduled activity would be replacing the inverter in about 6yrs? What, if any local and federal incentives can help this time around?

Thanks!

I had the same dilemma recently -- I ended up going with a second separate system for several reasons:

1) couldn't add enough panels to existing system to get the added generation I wanted -- I could add maybe one or two panels to each of two strings of ten I had.
2) Can't buy the same panels anymore! And they have to be current-matched to add them in series -- didn't look easy to find something that would be a good match.
3) Had to put them in a different part of the roof anyway.
4) Wanted the modern microinverter type, with net connection for monitoring.

That said, I have had the same inverters for over 8 years and have not had them go out on me yet.

Note that the big-name solar installers have rip-off prices. The panels now cost half what they did a couple years ago, and these companies are not passing on the savings, from what I can tell. I got a quick quote from a couple of the big ones in the Bay Area (you can probably guess), and it was as much per watt as I paid in 2004. I found a guy with a small install business that gave me a much better deal.

--Steve
 
Similar story here. My 9 year old system consists of four arrays of 30 panels each. I had an installer give me an assessment and he said since my bills are so small I should just leave it alone. He said things have changed so much he wouldn't touch my old system.
 
DesertDenizen said:
Similar story here. My 9 year old system consists of four arrays of 30 panels each. I had an installer give me an assessment and he said since my bills are so small I should just leave it alone. He said things have changed so much he wouldn't touch my old system.

120 panels? Holy cow, you could power several LEAFs! But I guess air conditioning is pretty crazy in AZ.
 
DesertDenizen said:
The sad part is the 120 panels provides only 4 kwh. Nine years ago was several generations ago of panel technology.


4 kwh DC or AC?

I just did the calulations for my area and figure I'd want around 5 to 7 kwh DC system when they get cheap enough to install one.
 
There is one inverter for each of the four arrays of 30 panels each. My house is all electric, and even now with the Leaf most months I don't have a cost for electricity.
 
Thanks again everyone for sharing your experiences! It helps,

leafedbehind - We chose to install Sunpower panels as they were the most efficient at the time for our small roof space. Per Sunpower's website, looks like they still make the ones we have, but prices haven't dropped like for other brands. Per our original installer, it'll cost us $4k to add 3 more panels. The California incentive has diminished to almost nothing, but I'm guessing we can still gave a federal tax credit of 30%.

DesertDenizen - Lucky you that what you did install 9 yrs ago still covers all your needs. Good on you being a pioneer going solar then! I wished we invested more at the get-go. Like with our electric vehicles, I though solar technology might change quickly and costs would come down.

dhanson865 - We only have 2.2kW AC or 2.5kW DC) :( 5-7kWAC or DC would be much better. Is solar kW more often quoted in AC or DC?
 
GoingGreener said:
Thanks again everyone for sharing your experiences! It helps,

leafedbehind - We chose to install Sunpower panels as they were the most efficient at the time for our small roof space. Per Sunpower's website, looks like they still make the ones we have, but prices haven't dropped like for other brands. Per our original installer, it'll cost us $4k to add 3 more panels. The California incentive has diminished to almost nothing, but I'm guessing we can still gave a federal tax credit of 30%.

DesertDenizen - Lucky you that what you did install 9 yrs ago still covers all your needs. Good on you being a pioneer going solar then! I wished we invested more at the get-go. Like with our electric vehicles, I though solar technology might change quickly and costs would come down.

dhanson865 - We only have 2.2kW AC or 2.5kW DC) :( 5-7kWAC or DC would be much better. Is solar kW more often quoted in AC or DC?

G Greener- Yes, you would get the 30% tax credit for any solar that you add on. Solar kw's are more commonly quoted in DC.

$4k for 3 panels? It's amazing to me how contractors disrespect, and don't appreciate, their own customers. Give me a call and I'll take care of it for you. Mark 925.212-7433
 
Thanks Mothernaturesolar for your help. I'm not sure if the verbal quoted cost is due to the panel brand, local permits (higher in the city?), and/or installation supplies (better quality) used.
 
GoingGreener said:
We have a small solar array that's almost 4 yrs. old. Charging the LEAF at home brings us back up to the higher PG&E electric rate tiers. Our electricity bill has been about $60-$70/month more than pre-LEAF. Some of the increased costs could also be attributed to changes in other household electrical use too. We have driven the LEAF about 9,000 miles annually. 3 more Sunpower SPR-230 panels can be added with the current inverter we have.

Would it make sense to do that (Cost/efficiency degradation of current panels, etc...)? Would permits need to be obtained again? Or better to add another separate/new efficient system? If I remember correctly, the next scheduled activity would be replacing the inverter in about 6yrs? What, if any local and federal incentives can help this time around?

Thanks!

It makes sense to expand your PV system to cover the Leaf. That is what I did last year.
You are supposed to get permits again for the expansion indeed.

Since you are using a big inverter as opposed to micro inverters, you will indeed have to replace it eventually. I don't know at what point you will want to do that. If it was me, I would not replace it until it actually fails.

You can certainly add a secondary system on a separate circuit to cover the Leaf. I would highly recommend one based on enphase micro inverters. These will last longer than big inverters.

The incentives currently are 30% federal tax credit and a small CSI rebate which is down to only 20 cents / watt.

I did my expansion in October 2012 which consisted of 12 Talesun 240W panels (cheap chinese panels) and 12 older Enphase M190 for $8500 total.
I haven't filed the CSI papework yet, but I expect it will be about $500. So $8000 could be claimed as solar property installed in 2012. Thus I would get a $2400 federal tax credit. Ie the net cost of the addition after the CSI rebate and federal tax credit will be $5600 .
If you PM me I can give you the references to my contractor who did a very good job and passed inspection the first time around.
 
madbrain said:
GoingGreener said:
We have a small solar array that's almost 4 yrs. old. Charging the LEAF at home brings us back up to the higher PG&E electric rate tiers. Our electricity bill has been about $60-$70/month more than pre-LEAF. Some of the increased costs could also be attributed to changes in other household electrical use too. We have driven the LEAF about 9,000 miles annually. 3 more Sunpower SPR-230 panels can be added with the current inverter we have.

Would it make sense to do that (Cost/efficiency degradation of current panels, etc...)? Would permits need to be obtained again? Or better to add another separate/new efficient system? If I remember correctly, the next scheduled activity would be replacing the inverter in about 6yrs? What, if any local and federal incentives can help this time around?

Thanks!

It makes sense to expand your PV system to cover the Leaf. That is what I did last year.
You are supposed to get permits again for the expansion indeed.

Since you are using a big inverter as opposed to micro inverters, you will indeed have to replace it eventually. I don't know at what point you will want to do that. If it was me, I would not replace it until it actually fails.

You can certainly add a secondary system on a separate circuit to cover the Leaf. I would highly recommend one based on enphase micro inverters. These will last longer than big inverters.

The incentives currently are 30% federal tax credit and a small CSI rebate which is down to only 20 cents / watt.

I did my expansion in October 2012 which consisted of 12 Talesun 240W panels (cheap chinese panels) and 12 older Enphase M190 for $8500 total.
I haven't filed the CSI papework yet, but I expect it will be about $500. So $8000 could be claimed as solar property installed in 2012. Thus I would get a $2400 federal tax credit. Ie the net cost of the addition after the CSI rebate and federal tax credit will be $5600 .
If you PM me I can give you the references to my contractor who did a very good job and passed inspection the first time around.
The good news about the central inverter is that the modern high-frequency units are expected to last 30 years on average. There's good engineering behind that MTBF. I've yet to see anything, or hear anything from either inverter manufacturers or those that have been watching the industry for more than 40 years, that suggests micros will outlast central inverters.
 
AndyH said:
The good news about the central inverter is that the modern high-frequency units are expected to last 30 years on average. There's good engineering behind that MTBF. I've yet to see anything, or hear anything from either inverter manufacturers or those that have been watching the industry for more than 40 years, that suggests micros will outlast central inverters.

Enphase is certainly claiming that their units will last a lifetime now.
They claim MTBF of 365 years on the M215 . And they offer warranty of 25 years.

What are the numbers on the best central inverters nowadays ?
 
madbrain said:
AndyH said:
The good news about the central inverter is that the modern high-frequency units are expected to last 30 years on average. There's good engineering behind that MTBF. I've yet to see anything, or hear anything from either inverter manufacturers or those that have been watching the industry for more than 40 years, that suggests micros will outlast central inverters.

Enphase is certainly claiming that their units will last a lifetime now.
They claim MTBF of 365 years on the M215 . And they offer warranty of 25 years.

What are the numbers on the best central inverters nowadays ?

Make sure you read their white paper on what exactly an MTBF of 365 years means. It's not to say that they'll last 365 years.

Last I heard many central inverters still have less than 10 year warranties but the standard was 10 years and some are selling extended warranties doubling to 20.
 
QueenBee said:
madbrain said:
AndyH said:
The good news about the central inverter is that the modern high-frequency units are expected to last 30 years on average. There's good engineering behind that MTBF. I've yet to see anything, or hear anything from either inverter manufacturers or those that have been watching the industry for more than 40 years, that suggests micros will outlast central inverters.

Enphase is certainly claiming that their units will last a lifetime now.
They claim MTBF of 365 years on the M215 . And they offer warranty of 25 years.

What are the numbers on the best central inverters nowadays ?

Make sure you read their white paper on what exactly an MTBF of 365 years means. It's not to say that they'll last 365 years.

Last I heard many central inverters still have less than 10 year warranties but the standard was 10 years and some are selling extended warranties doubling to 20.
I didn't say warranty or other marketing-speak - I'm speaking of actual life in the field.

Contact the folks at HomePower magazine (Richard Perez) as they've got independent info from inverter manufacturers and have been off grid for more than 30 years and testing inverters for about 25 years. Also ping Robin Gudgel at Midnight Solar. He's one of the designers of the Outback inverters, but that was after time with Heart Interface and Trace. They're also working with all major inverter manufacturers (and working on a new inverter of their own).

http://www.hardysolar.com/inverter/inverter-history.html
http://midnitesolar.com/
http://www.homepower.com/

Edit... Here's a quote from Homepower's Richard Perez, speaking at the Midwest Renewable Energy Fair in 1999 about modern off-grid inverters:
In the early days a good inverter would go, eh, six months, we had some that lasted as little as three weeks before they blew up. Those Days Are Gone. These inverters are rock solid. The Traces, StatPower, the Exeltechs, they rarely fail...I asked the people at Exeltech, who keep track of this stuff, what is your mean time before failure?...How many units do you have out there, how long have they been out there, and how many come back DOA 'please fix this for me'? Thirty-two years. This is phenomenal reliability. So the days when the inverters lasted a week or two and blow up in our face is long gone. ...It means you can buy it and chances are it will never break...
 
AndyH said:
I didn't say warranty or other marketing-speak - I'm speaking of actual life in the field.

Contact the folks at HomePower magazine (Richard Perez) as they've got independent info from inverter manufacturers and have been off grid for more than 30 years and testing inverters for about 25 years. Also ping Robin Gudgel at Midnight Solar. He's one of the designers of the Outback inverters, but that was after time with Heart Interface and Trace. They're also working with all major inverter manufacturers (and working on a new inverter of their own).

http://www.hardysolar.com/inverter/inverter-history.html
http://midnitesolar.com/
http://www.homepower.com/

Edit... Here's a quote from Homepower's Richard Perez, speaking at the Midwest Renewable Energy Fair in 1999 about modern off-grid inverters:
In the early days a good inverter would go, eh, six months, we had some that lasted as little as three weeks before they blew up. Those Days Are Gone. These inverters are rock solid. The Traces, StatPower, the Exeltechs, they rarely fail...I asked the people at Exeltech, who keep track of this stuff, what is your mean time before failure?...How many units do you have out there, how long have they been out there, and how many come back DOA 'please fix this for me'? Thirty-two years. This is phenomenal reliability. So the days when the inverters lasted a week or two and blow up in our face is long gone. ...It means you can buy it and chances are it will never break...

I don't understand what he means by "Thirty-two years" in response to the questions he asked. Thanks for sharing that inverter history; I've wondered how we ended up with multiple inverter companies in WA.

You can call it marketing-speak but are you telling me every grid-tied inverter manufacturer I looked at on hardysolar.com is run by people that don't know how to market their products when the reality "means you can buy it and chances are it will never break"????? If so you need to get hired on as the marketing executive for any one of these companies and convince them to offer lifetime warranties, it'll be an industry first and the industry will either laugh because the company will not be in business to live up to the lifetime warranty or it'll push them to the head of the back.

OutBack: "Standard 2 year / Optional 5 year"
Magnum Energy is similiar "New Warranty Three-year warranty standard. Five-year warranty if installed on an MP or MMP panel."
MidNite is 5 years

Solectria is 5 year and also has 10 year models
SMA Sunny Boy, Xantrax, Fronius, PV Powered, Kaco is 10 years (SMA has optional 15/20 year warranties too)
Beacon Power is 5 years
 
QueenBee said:
AndyH said:
I didn't say warranty or other marketing-speak - I'm speaking of actual life in the field.

Contact the folks at HomePower magazine (Richard Perez) as they've got independent info from inverter manufacturers and have been off grid for more than 30 years and testing inverters for about 25 years. Also ping Robin Gudgel at Midnight Solar. He's one of the designers of the Outback inverters, but that was after time with Heart Interface and Trace. They're also working with all major inverter manufacturers (and working on a new inverter of their own).

http://www.hardysolar.com/inverter/inverter-history.html
http://midnitesolar.com/
http://www.homepower.com/

Edit... Here's a quote from Homepower's Richard Perez, speaking at the Midwest Renewable Energy Fair in 1999 about modern off-grid inverters:
In the early days a good inverter would go, eh, six months, we had some that lasted as little as three weeks before they blew up. Those Days Are Gone. These inverters are rock solid. The Traces, StatPower, the Exeltechs, they rarely fail...I asked the people at Exeltech, who keep track of this stuff, what is your mean time before failure?...How many units do you have out there, how long have they been out there, and how many come back DOA 'please fix this for me'? Thirty-two years. This is phenomenal reliability. So the days when the inverters lasted a week or two and blow up in our face is long gone. ...It means you can buy it and chances are it will never break...

I don't understand what he means by "Thirty-two years" in response to the questions he asked.
It truly means exactly what it is! Exeltech makes a lot of equipment for the military - it's built like, well, a tank. What he said in the talk (which was expanded on a bit later during Q&A) was that when the top-tier companies put an inverter in the field, it's likely to stay there a very long time unless struck by lightning. There's a good possibility that the top-tier inverter manufactures use longer life capacitors - that'll likely be the limiting factor barring lightning.

Here's the 1999 MREF/Perez inverter talk, in case you need some help going to sleep. ;)
https://www.dropbox.com/s/fa3fqshepp04igp/INVERT.WAV The reliability info is about 28:52 in, with a bit more later in the Q&A.

QueenBee said:
Thanks for sharing that inverter history; I've wondered how we ended up with multiple inverter companies in WA.
Glad to help.

QueenBee said:
You can call it marketing-speak but are you telling me every grid-tied inverter manufacturer I looked at on hardysolar.com is run by people that don't know how to market their products when the reality "means you can buy it and chances are it will never break"????? If so you need to get hired on as the marketing executive for any one of these companies and convince them to offer lifetime warranties, it'll be an industry first and the industry will either laugh because the company will not be in business to live up to the lifetime warranty or it'll push them to the head of the back.

OutBack: "Standard 2 year / Optional 5 year"
Magnum Energy is similiar "New Warranty Three-year warranty standard. Five-year warranty if installed on an MP or MMP panel."
MidNite is 5 years

Solectria is 5 year and also has 10 year models
SMA Sunny Boy, Xantrax, Fronius, PV Powered, Kaco is 10 years
Beacon Power is 5 years
With respect, we're still talking about two different things. I've got about 10 years of industrial sales experience and study and will try to compare/contrast the 'sales' world and the 'real' world. When I say that I'm talking about a real-world expectation, I'm speaking from the position of an end user that has an inverter and is wondering if I should buy a spare to put in the attic. A warranty, on the other hand, is a marketing tool designed to provide a purchaser enough of a comfort cushion to make it easier to buy the product, but not keep the company on the hook any longer than necessary. Regardless of warranty, a good company is going to take care of the customer because the only things that'll give them a long business life are their products, their customers, and their reputation.

Early inverters did have reliability problems - they were new and needed to evolve. Microinverter sales copy uses the early inverter history to suggest that a central inverter will have a short lifespan - that's typical sales -- push your competition's weaknesses (and if they don't have any, dig deeper) while touting your strengths (and ignoring, downplaying, or trivializing your product's weaknesses). Sales folks aren't in business to provide a level playing field, or to sell their competition, they're there to sell their own. Some take more liberties with the truth than others...unfortunately.

It appears from the little bit of literature I can find that life is tougher for grid-tied inverters. It appears that there's been a fast evolution in inverter tech since the late '90s and early 2000s that is extending inverter service life. It's also clear that the environment between a roof and a solar panel is tough duty for electronic devices.

Older articles/forum posts:
http://ieeexplore.ieee.org/xpl/logi...re.ieee.org/xpls/abs_all.jsp?arnumber=1190860
http://ecee.colorado.edu/~ecen4517/materials/refs/inverters/BonnInverter.pdf
http://www.energiasrenovables.ciemat.es/adjuntos_documentos/Alonso refs.pdf

http://www.thebackshed.com/forum/forum_posts.asp?TID=1686
http://www.ata.org.au/forums/topic/709

Current info (for commercial systems in outdoor/all weather service):
Mar 2002:
http://www.solelprogrammet.se/Globa...PDF/herman laukamp fin_rep.pdf?epslanguage=sv
A theoretical analysis shows that inverter should have a “Mean Time Between Failures” (MTBF) about 50 years as long as they are not exposed to excessive temperature. (For example, mounted directly at a module without any rear side ventilation.) (Wilk 1997).

Actual experience is quite different.
As can be seen from figures 1 and 2 inverters were the most vulnerable component in PV systems. This observation was unanimously supported from all countries.
Data for figures 1 and 2 was mostly gained from older types of inverters. It is a very interesting question, if new products demonstrate improvements

Oct 2012:
http://electronicdesign.com/power/a...logies-boost-solar-power-inverter-reliability
Encased in a ruggedized package, the inverter is designed to remain in full-power operation for more than 25 years.

Whatever you use, install good surge suppressors. (I promise - I'm not affiliated with Midnite in any way. My first small grid-tied system used Delta suppressors. ;))

[youtube]http://www.youtube.com/watch?v=_ciAkYZzfDo[/youtube]

[youtube]http://www.youtube.com/watch?v=vkeFYuHxJoU[/youtube]

I chose a central inverter for three reasons.
- The first is that I'm building an off-grid system that will not be grid-tied. The central inverter has more than one function - it also has an automatic cross-over switch and controller that can start a generator, and it has an 80A battery charger.
- The second is that should the inverter need service there's only one of them. There are fewer capacitors to change when they reach end of life. In the event of failure, I replace one component and do not have to touch the solar array.
- The third is that a central inverter will be indoors - away from excess heat or cold - and will be isolated from the very dirty power grid. Other off-gridders that have similar conditions have very long inverter lives.

Good advice I received from an off-grid mentor:
Contact inverter manufacturers and/or your perspective vendors and pose as a customer with a failed inverter. Evaluate their customer service response - how long did it take to get a response (provided you got one...), would they send a replacement or loaner inverter? Will they rebuild/refurbish their units near the end of warranty? etc. That's another reason I went Outback and Midnite.
 
AndyH said:
Edit... Here's a quote from Homepower's Richard Perez, speaking at the Midwest Renewable Energy Fair in 1999 about modern off-grid inverters:
In the early days a good inverter would go, eh, six months, we had some that lasted as little as three weeks before they blew up. Those Days Are Gone. These inverters are rock solid. The Traces, StatPower, the Exeltechs, they rarely fail...I asked the people at Exeltech, who keep track of this stuff, what is your mean time before failure?...How many units do you have out there, how long have they been out there, and how many come back DOA 'please fix this for me'? Thirty-two years. This is phenomenal reliability. So the days when the inverters lasted a week or two and blow up in our face is long gone. ...It means you can buy it and chances are it will never break...
QueenBee said:
I don't understand what he means by "Thirty-two years" in response to the questions he asked.
It truly means exactly what it is! Exeltech makes a lot of equipment for the military - it's built like, well, a tank. What he said in the talk (which was expanded on a bit later during Q&A) was that when the top-tier companies put an inverter in the field, it's likely to stay there a very long time unless struck by lightning. There's a good possibility that the top-tier inverter manufactures use longer life capacitors - that'll likely be the limiting factor barring lightning.

It truly means exactly what it is?
what is your mean time before failure?
Thirty-two years.
How many units do you have out there?
Thirty-two years.
how long have they been out there?
Thirty-two years.
how many come back DOA 'please fix this for me?
Thirty-two years.

I certainly hope the MTBF isn't 32 years since modules are said to have a 600 years MTBF and Enphase is above 300 years. Although what that actually tells about the three products is questionable.

QueenBee said:
You can call it marketing-speak but are you telling me every grid-tied inverter manufacturer I looked at on hardysolar.com is run by people that don't know how to market their products when the reality "means you can buy it and chances are it will never break"????? If so you need to get hired on as the marketing executive for any one of these companies and convince them to offer lifetime warranties, it'll be an industry first and the industry will either laugh because the company will not be in business to live up to the lifetime warranty or it'll push them to the head of the back.

OutBack: "Standard 2 year / Optional 5 year"
Magnum Energy is similiar "New Warranty Three-year warranty standard. Five-year warranty if installed on an MP or MMP panel."
MidNite is 5 years

Solectria is 5 year and also has 10 year models
SMA Sunny Boy, Xantrax, Fronius, PV Powered, Kaco is 10 years
Beacon Power is 5 years
AndyH said:
With respect, we're still talking about two different things. I've got about 10 years of industrial sales experience and study and will try to compare/contrast the 'sales' world and the 'real' world. When I say that I'm talking about a real-world expectation, I'm speaking from the position of an end user that has an inverter and is wondering if I should buy a spare to put in the attic. A warranty, on the other hand, is a marketing tool designed to provide a purchaser enough of a comfort cushion to make it easier to buy the product, but not keep the company on the hook any longer than necessary. Regardless of warranty, a good company is going to take care of the customer because the only things that'll give them a long business life are their products, their customers, and their reputation.

I have none so I'm just an outsider but from my point of view warranties are a balancing act between making the product and/or warranty affordable/cheaper and providing the customer with confidence that your product is reliable. If a car came with a 1 year warranty I'd be pretty suspect even it was significantly cheaper. If a car came with a 20 year warranty I don't think I'd want to pay what it would cost for them to make money on that transaction. So to me the fact that central inverters come with 2/5/10 year warranties is a sign that they expect failure rates to increase after those time periods and significantly enough that they can't afford to accept responsibility for the warranties. In the end it's all about perception and my perception along with a lot of other peoples is that central inverters come with shorter warranties because they are expected to have shorter lives. For example what kind of maintenance does a PV system really need? If you use the default values of http://pvcalc.org/pvcalc" onclick="window.open(this.href);return false; they say .5% per year in maintenance, so for a $10,000 system you've got $5,000 after 10 years, which would certainly pay to replace the inverter, and I have no idea what else.... Anyway my point just being that I'm certainly not the first person to have the perception that one should plan(budget) for replacing a central inverter after 10 years.

Now back to reality Enphase and other microinverter manufacturers may end up really hurting if it turns out their products don't last 25 years and they are replacing more of them than budgeted.

I chose Enphase microinverters the first time around and now the second time around for various reasons. Some of them being 25 year warranty is a great sales pitch that works well on me, since it's DIY the extra complexity caused by strings, string sizes, sizing the inverter(s), picking a manufacturer, figuring out how the various monitoring solutions compare, DC wiring, additional NEC requirements for DC. Then you add in that I'm heavily shaded at different times of the day/year and it makes the decision pretty easy. Plus I love seeing the individual output of each panel. Now had I been off the grid most of the above reasoning doesn't matter any more and the important fact that it needs to work off the grid makes Outback come to the top.


AndyH said:
Whatever you use, install good surge suppressors. (I promise - I'm not affiliated with Midnite in any way. My first small grid-tied system used Delta suppressors. ;))

I came across that second video when I was looking up their warranties and was pretty shocked. It made me really wonder if the GE "breaker style" surge suppressor I used is adequate enough. If a "name brand" like Delta is selling a product that is performing so poorly then I don't have much confidence in my GE one. Looks like I'll have to order one of their SPDs for my second system. Thanks for sharing this!
 
QueenBee said:
AndyH said:
Edit... Here's a quote from Homepower's Richard Perez, speaking at the Midwest Renewable Energy Fair in 1999 about modern off-grid inverters:
In the early days a good inverter would go, eh, six months, we had some that lasted as little as three weeks before they blew up. Those Days Are Gone. These inverters are rock solid. The Traces, StatPower, the Exeltechs, they rarely fail...I asked the people at Exeltech, who keep track of this stuff, what is your mean time before failure?...How many units do you have out there, how long have they been out there, and how many come back DOA 'please fix this for me'? Thirty-two years. This is phenomenal reliability. So the days when the inverters lasted a week or two and blow up in our face is long gone. ...It means you can buy it and chances are it will never break...
QueenBee said:
I don't understand what he means by "Thirty-two years" in response to the questions he asked.
It truly means exactly what it is! Exeltech makes a lot of equipment for the military - it's built like, well, a tank. What he said in the talk (which was expanded on a bit later during Q&A) was that when the top-tier companies put an inverter in the field, it's likely to stay there a very long time unless struck by lightning. There's a good possibility that the top-tier inverter manufactures use longer life capacitors - that'll likely be the limiting factor barring lightning.

It truly means exactly what it is?
what is your mean time before failure?
Thirty-two years.
How many units do you have out there?
Thirty-two years.
how long have they been out there?
Thirty-two years.
how many come back DOA 'please fix this for me?
Thirty-two years.

I certainly hope the MTBF isn't 32 years since modules are said to have a 600 years MTBF and Enphase is above 300 years. Although what that actually tells about the three products is questionable.
You might have missed this part: "...It means you can buy it and chances are it will never break..." ;)

I understand that it can be confusing when information intended to be used in one realm leaks into another. As I said, it's a look at expected life in the field, not engineering statistics or warranty copy or marketing-speak. That was the context of Joe Perez's "32 years" statement - give the audio a listen and evaluate it for yourself. The best advice I can offer is to contact manufacturers and ask then directly: "Once I buy your inverter and install it in accordance with applicable rules/codes, et al, how many years can I expect it to continue to work as designed (barring acts of nature, war, theft, etc.)? (And validate your answers with independent folks that monitor the industry - like HomePower, the NREL, etc.)

QueenBee said:
QueenBee said:
You can call it marketing-speak but are you telling me every grid-tied inverter manufacturer I looked at on hardysolar.com is run by people that don't know how to market their products when the reality "means you can buy it and chances are it will never break"????? If so you need to get hired on as the marketing executive for any one of these companies and convince them to offer lifetime warranties, it'll be an industry first and the industry will either laugh because the company will not be in business to live up to the lifetime warranty or it'll push them to the head of the back.

OutBack: "Standard 2 year / Optional 5 year"
Magnum Energy is similiar "New Warranty Three-year warranty standard. Five-year warranty if installed on an MP or MMP panel."
MidNite is 5 years

Solectria is 5 year and also has 10 year models
SMA Sunny Boy, Xantrax, Fronius, PV Powered, Kaco is 10 years
Beacon Power is 5 years
AndyH said:
With respect, we're still talking about two different things. I've got about 10 years of industrial sales experience and study and will try to compare/contrast the 'sales' world and the 'real' world. When I say that I'm talking about a real-world expectation, I'm speaking from the position of an end user that has an inverter and is wondering if I should buy a spare to put in the attic. A warranty, on the other hand, is a marketing tool designed to provide a purchaser enough of a comfort cushion to make it easier to buy the product, but not keep the company on the hook any longer than necessary. Regardless of warranty, a good company is going to take care of the customer because the only things that'll give them a long business life are their products, their customers, and their reputation.

I have none so I'm just an outsider but from my point of view warranties are a balancing act between making the product and/or warranty affordable/cheaper and providing the customer with confidence that your product is reliable. If a car came with a 1 year warranty I'd be pretty suspect even it was significantly cheaper. If a car came with a 20 year warranty I don't think I'd want to pay what it would cost for them to make money on that transaction. So to me the fact that central inverters come with 2/5/10 year warranties is a sign that they expect failure rates to increase after those time periods and significantly enough that they can't afford to accept responsibility for the warranties. In the end it's all about perception and my perception along with a lot of other peoples is that central inverters come with shorter warranties because they are expected to have shorter lives. For example what kind of maintenance does a PV system really need? If you use the default values of http://pvcalc.org/pvcalc" onclick="window.open(this.href);return false; they say .5% per year in maintenance, so for a $10,000 system you've got $5,000 after 10 years, which would certainly pay to replace the inverter, and I have no idea what else.... Anyway my point just being that I'm certainly not the first person to have the perception that one should plan(budget) for replacing a central inverter after 10 years.
This is EXACTLY my point! The error I see in your analysis is trying to make a connection between a marketing device (warranty) and an engineering/design device (MTTF/MTBF). Those are two completely different things managed by two completely different groups within a company. I agree with your view of how this might affect the end user's perception - that's exactly why it's touted (or ignored) by sales folk. Thank you - you've just validated that sales techniques work! ;)

I'm not at all surprised with the PVCALC info or other references that speak of 5-10 year inverter lives. They're simply based on info that isn't yet updated to reflect equipment coming off the shelf since about 2000 or so. That's the way things work when it comes to literature reviews and products derived from industry experience - it's all either older info or info that's still skewed by older equipment still in service. If an inverter fairy replaced all inverters in the field with devices manufactured since about 2010 and then updated all the literature and spreadsheets to reflect that new reality, the pvcalc numbers would be different. That's why I think papers like the one I linked from Europe better reflect the 'new reality' of modern inverters as they've been installing a very significant number of systems over the past 5-10 years and their reliability numbers though young will be skewed toward 'modern' equipment while US numbers will be skewed to a mass of 'older' equipment.
http://www.solelprogrammet.se/Globa...PDF/herman laukamp fin_rep.pdf?epslanguage=sv

QueenBee said:
Now back to reality Enphase and other microinverter manufacturers may end up really hurting if it turns out their products don't last 25 years and they are replacing more of them than budgeted.
Yes, 'reality' ;) I'm aware you're a micro-inverter person, and that's fine. I agree in general with your view in this sentence, yet from the perspective of someone that's been a sales professional, and from the additional view of someone that's operated a small business manufacturing, selling, and supporting tech devices, I have to remind you that the flaw in your logic is that even if a significant percentage of inverters fail, the REALITY is that only about 20% of failures will be returned to a company for replacement! That's also part of the manufacturer's calculus when designing their warranty. Again - a warranty is a marketing device - and marketing is tax deductable by businesses. ;)

QueenBee said:
I chose Enphase microinverters the first time around and now the second time around for various reasons. Some of them being 25 year warranty is a great sales pitch that works well on me, since it's DIY the extra complexity caused by strings, string sizes, sizing the inverter(s), picking a manufacturer, figuring out how the various monitoring solutions compare, DC wiring, additional NEC requirements for DC. Then you add in that I'm heavily shaded at different times of the day/year and it makes the decision pretty easy. Plus I love seeing the individual output of each panel. Now had I been off the grid most of the above reasoning doesn't matter any more and the important fact that it needs to work off the grid makes Outback come to the top.
I can certainly respect this! While I personally find string sizing, calculating I2R losses, etc. to be a 'fun' part of the process, I realize not all solar folks are geeks/nerds/electronics hobbyists. ;) All of my monitoring is handled by the charger controller, the inverter, and the TriMetric and I can simply walk down the hall to check the numbers, so I don't feel the need for a web interface to check on how each panel is performing. I'd say that your shading challenges are the number one reason to either split an array, use per-panel MPPT devices, or microinverters - even if they result in a more expensive system.

I think it's useful to point out that any inverter installed in a 75°F space at ~45% humidity is going to have a much longer life than if that same device is installed on a roof between shingles and a solar panel - that's tough duty for an electronic device. As I see it, the corollary is that a device designed to go under a panel MUST use higher quality components if it's to have a long service life. That's covered in one of the studies I linked above - there's been a LOT of progress in all inverters in the past 10 years.

A related observation/marketing example: A marketing division will tout that they use military grade hardware or long-life capacitors or don't use optical isolation and their competition does. This is a case where facts are used out of context to spin an almost-lie. If one designs an inverter to live inside a living space and last 10 years, they can use low-grade capacitors - they'll provide more than enough life to meet that goal. Those same capacitors will NOT last 10 years when put on a roof under a solar panel where it might be 160°F in the summer. To last for the same 10 years, a microinverter manufacturer MUST make different choices in order to have the same reliability. Marketing will spin 'higher quality components' to their advantage to lead or cause a consumer to assume better components equals longer life. (That might be true if the microinverters are installed inside next to a central inverter, but that's not how they're intended to be used.) The marketing folks do that on purpose, and will NOT 'correct' the customer that develops the false assumption.


QueenBee said:
AndyH said:
Whatever you use, install good surge suppressors. (I promise - I'm not affiliated with Midnite in any way. My first small grid-tied system used Delta suppressors. ;))

I came across that second video when I was looking up their warranties and was pretty shocked. It made me really wonder if the GE "breaker style" surge suppressor I used is adequate enough. If a "name brand" like Delta is selling a product that is performing so poorly then I don't have much confidence in my GE one. Looks like I'll have to order one of their SPDs for my second system. Thanks for sharing this!
Absolutely! I've used a number of different whole-house suppressors and found out the hard way that they didn't live up to the sales-speak claims. I strongly suggest that anyone with questions should bypass sales/marketing and go directly to engineering. It's sad, but sales divisions take great pride in bending the truth almost to the point of breaking when writing copy, and some sales folk outright lie. I put plenty of faith in info from the design/engineering folks but zero in warranties or sales info. FWIW.
 
AndyH said:
This is EXACTLY my point! The error I see in your analysis is trying to make a connection between a marketing device (warranty) and an engineering/design device (MTTF/MTBF). Those are two completely different things managed by two completely different groups within a company. I agree with your view of how this might affect the end user's perception - that's exactly why it's touted (or ignored) by sales folk. Thank you - you've just validated that sales techniques work! ;)

Sorry, but the fact that there are different groups involved for engineering and marketing is irrelevant.
Whatever the marketing group decides in terms of warranty length, the company has to consider the cost of honoring that warranty. Are you seriously suggesting that nobody in the company would consult with their engineering group to attempt to predict what those warranty costs might turn out to be ?

It's not in the interest of the company to overpromise in terms of warranty, if they are not able to actually deliver on it. The company would soon be history if that happened. There are two sides of the coin. Any reasonably run business would do a cost-benefit analysis.
IMO, the fact than Enphase used to offer 15 years standard warranty and now 25 years on their newer micro-inverters speaks to the fact that they expect to be able to honor the warranty somehow. Maybe it's because they really expect their products to last that long. Maybe it's because their products cost more per watt than string inverters in general, so they have more reserves to cover warranty claims. I like to think that it's a little bit of both.

It seems to me that the string inverters manufacturers have determined that they can't afford to offer and honor any warranties greater than 10 years. Why do you think that is ? If their products are as reliable as you say, why aren't they also offering 15 or 25 year standard warranties on any product, or even 15 or 25 year extended warranties on current product, at any price point?
 
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