Solar Panel Questions...

[donauker]

Just the micro-inverter would need to be replaced, not the panel.
/Ed

Yes the micro-inverter can be replaced, the problem is getting to it. With this array of 60 panels there would be 60 inverters in a rather brutal environment with temperatures ranging from below 0F to high in the 100's. When these panels are installed one by one from end to end the wires are carefully bundled and tied so there is no slack to allow movement which could quickly wear a wire through with the rough asphalt shingles inches away. I can't imagine what would be involved in replacing an inverter in the middle of this array.

Given my zero percent shading issue and my experience with electronics in hot environments I didn't even consider adding 60 failure points under the array. I am much happier with two inverters in my basement where the temperature is always between 60 and 80F and I can readily swap one out in under 30 minutes

 

[shark2k]

For those that are interested, this is one of the single solar panels I was talking about. You can see the micro-inverter in the corner of the panel.

-Shark2k

 

[Zythryn]

All right, I need some help, and rather than starting a new thread I thought I would resurrect this one

I'm working on bids for a new solar array on a yet-to-be constructed house.

I have spoken with multiple installers, some love micro inverters and have had issues with SMA (Sunnyboy) string inverters in the 7-10 year range.
Others hate the micro inverters, and find them unreliable.

So since a number of you have years of experience with your own systems, I thought I would ask here...
What has been your experience with the reliability of either the micro or string inverters that you have?

 

[Xenoilphobe]

I have micro inverters on my panels - no issues to date - did the install myself - (minus the grid tie and electrical connections.)

The warranty on the panel is the same for the micro inverter- in my case 25 years.

Guaranteed output of 90% for 10 years and 80%for 25 years http://pdf.wholesalesolar.com/module pdf folder/AUO-ACUnison-PM250MA0.pdf

 

[Zythryn]

I have micro inverters on my panels - no issues to date - did the install myself - (minus the grid tie and electrical connections.)

The warranty on the panel is the same for the micro inverter- in my case 25 years.

Guaranteed output of 90% for 10 years and 80%for 25 years http://pdf.wholesalesolar.com/module pdf folder/AUO-ACUnison-PM250MA0.pdf

Thanks for your experience! How long has your PV system been running?

 

[swaltner]

I've got a 5 kW system (21 x 240W panels) that's been up for 2.5 years without a single problem. I'm closing in 20 MWh of production since it was installed! My system uses the Enphase M215 micro-inverters. Of course, we got 2" of snow yesterday, so I'm only producing 70 Watts of power right now in the middle of the day. The forecast is for a week of below freezing temps, so it'll likely stick around for a while.

From what I've read, the older (no longer available) Enphase M190 micro-inverters had infant mortality issues and may be what the local installers are concerned about. I know there is a thread over on the MyNissanLeaf.com forum tracking reliability of these older generation of micro-inverters. The reliability was pretty bad for many customers. Enphase does a good job of replacing the units when they've had trouble. I've peeked at the thread at times and haven't seen any references to the M215 having the same issue. The M250/C250 units are too new to have any kind of reliability data yet.

 

[Ampster]

I have two systems. The first on an apartment building I own and lived in for a while. That system used a single inverter and has been in operation for 3 years. I installed it myself. It works fine and now that I am not living there and charging my cars it generates a lot of surplus electricity.

The second system was just completed by Solar Max on a townhome my spouse and I recently purchased. It is a microinverter system and I love the data I get from the Enphase Envoy system. I priced both alternatves and all the bids came in around $4.50/Watt.

The next question to maximize your savings is to decide on a rate plan with your utility. I am with Southern California Edison and went with a Time of Use plan. I actually consumed more power than I generated, but because I was able to shift the timing of consumption I closed out my first bill with a negative dollar amount. For example I received credit for my generation at the peak rate of $0.25/kWh and charged my cars and heated my water at the super off peak rate of $0.09/kWh. I did not receive a refund check because the excess dollars went to pay for the excess consumption of power.
You will have to research what rate options are available in your area.

 

[dhrivnak]

I have a 7.1 KW system that has been on line for 16 months. I use the SunnyBoy SMA TL series and have been pleased with no issues. I really like the ability to generate at least some power while the grid is down. A friend of mine installed 40 panels with micro inverters and has replaced 6 of them. He said they have been good about sending him replacement inverters but as you can imagine it is a bit of a pain to swap out. To me if you have shading issue (I do not) microinverters do make sense.

If you have not done so (Especially those of you that have not gone solar) please count your vote on the Driving on Sunshine poll. Thank you Driving on Sunshine

 

[markb1]

No issues with my Enphase micro-inverters. My system just turned two years old.

 

[Xenoilphobe]

Thanks for your experience! How long has your PV system been running?

3 years now.

 

[ChrisPDX]

I have a smaller 14 panel setup. Like many others, I have the M215 Enphase micro-inverters. Not a single issue with any of them or the data collector for the last 2.75 years. The lifetime monitoring and 25 year warranty are really nice. Since I had an installer do it, any warranty claims are covered with them or an Enphase contractor for inverter replacement should that be needed.

 

[Robert.Boston]

In the horserace of "best PV panel", who is currently in the lead?

 

[RichardC]

In the horserace of "best PV panel", who is currently in the lead?

I don't know, but I have been pleased with the performance to date of our SunPower panels (more than four years).

 

[tezco]

I have a 10.2 kW Sunpower system with a Fronius string inverter. My installer said that you can expect to replace your inverter once during the 30 year life of the panels.

 

[nwdiver]

IMHO SunPower is the clear 'leader' but they're rather expensive unless you get 'B' grade. For the most part there doesn't seem to be much of a difference.

 

[wws]

...So since a number of you have years of experience with your own systems, I thought I would ask here...
What has been your experience with the reliability of either the micro or string inverters that you have?

We just installed a modest 3kw system a week ago. The installer I used has been in the solar business for a very long time. He always recommends micro-inverters. We used the Enphase M215s combined with 250w Auxin Solar panels (made here in San Jose, Cal.) While at it, we also installed a NEMA 14-50 outlet under the new subpanel with the solar cutoff breakers in it. ;-)

With micro-inverters, each panels output is optimized to its max, whereas with a single big inverter the system runs at however the worst panel is performing. This is important in my case since some of the panels are on the south facing roof and some on the west facing roof. With the Enphase logging capability, one can easily see the south facing panels wake up a few minutes before the west facing panels in the morning. In the afternoon the opposite occurs when they go to sleep.

 

[derekt75]

All right, I need some help, and rather than starting a new thread I thought I would resurrect this one

I'm working on bids for a new solar array on a yet-to-be constructed house.

I have spoken with multiple installers, some love micro inverters and have had issues with SMA (Sunnyboy) string inverters in the 7-10 year range.
Others hate the micro inverters, and find them unreliable.

So since a number of you have years of experience with your own systems, I thought I would ask here...
What has been your experience with the reliability of either the micro or string inverters that you have?

I've had my system for a few years with two Fronius inverters. The inverters have been fine, but some DC combiner failed after a couple years. I suspect you wouldn't have the DC combiner with micro-inverters, but would you instead have some kind of AC combiner that is just as likely to fail?

My system is a "prepaid lease", so I'm not overly concerned about failures. If something fails within 20 years, SolarCity fixes it. The prepaid lease was nearly half the price of the buy-it option and made it so I didn't have to worry about inverter failures or the quality of the Chinese panels, so it seemed to me like the right choice.

 

[ChrisPDX]

I've had my system for a few years with two Fronius inverters. The inverters have been fine, but some DC combiner failed after a couple years. I suspect you wouldn't have the DC combiner with micro-inverters, but would you instead have some kind of AC combiner that is just as likely to fail?

For Enphase, they have a trunk cable. Basically nothing more then a cable with outlets at regular intervals that the inverters plug into. Once you have all the inverters connected, you run the cable to an enclosure where you then connect to standard household wiring that runs back to your main cutoff switch and meter. So assuming the inverters are plugged in properly for a good seal, the cable should last forever as there is really nothing to it.

There are times where I wish I could show off a complex solar install to my engineering friends, but there really isn't much to it. All I can show are panels on the roof and some conduit in the garage that leads to a cutoff switch and meter before finally going to a circuit breaker in the main panel. So I guess you can call that a drawback in that it's really boring to show off. No fancy DC combiners or large central inverters to display.

 

[wws]

I've had my system for a few years with two Fronius inverters. The inverters have been fine, but some DC combiner failed after a couple years. I suspect you wouldn't have the DC combiner with micro-inverters, but would you instead have some kind of AC combiner that is just as likely to fail?

The Enphase setup uses a long cable with a connector every few feet. The cable comes on a big spool, and they cut off a length with as many connectors as they need. Each connector plugs into a microinverter. At the end of the run there is a J-box where the cable connects with a THHN run in conduit to the subpanel. A pair of breakers forms the cut-off switch. It is all pretty straightforward 240v wiring.

One thing I found interesting: As a safety measure, the inverters do not start inverting until they see grid power for several minutes.

 

[miimura]

Some installers don't like the micro-inverters because the installer is responsible for the labor to change it out. Their thinking is that even if the reliability of each one is the same as a string inverter, there are X of them up on the roof. So, it's X times more likely they have to go back out to the site at some later date, which costs them money. Also they have to go up on the roof to change out the micro-inverter while a string inverter is usually just bolted to a wall at shoulder height somewhere.

I had solar put on my house during construction. The installer got the two 240V circuits installed from the main panel to the attic while the walls were still open and they put the roof jacks on before the roofing was done. It's a very clean install and the 240V circuits are just Romex, not THHN in conduit. DC from the panels must always be in conduit, these 20A AC circuits do not need to be.