Help me decide - Microinverters?

[TimeOrMoney]

I was pretty much decided on going Enphase Microinverters on a 4 KW, 15-16 panel grid-tie ground mount system about 165 feet from the house. But now I realize that removing a couple of trees could mean no shading (other than snow or dirt, ha ha), meaning potentially I could go with a standard string inverter setup, if I don't decide to expand later. I've not designed a whole system with, say, Sunnyboy or Solaredge to compare the costs, but at first glance they seem pretty similar overall pricing, which was not what I expected. Thoughts? Experiences? Other considerations? I don't want to turn this into another Solaredge vs Enphase battle - they both have pluses and minuses. Rather, for my situation, what things should I consider?

[solar pete]

Howdy TimeorMoney, if you dont have shade issues and its ground mount I would be going with a string inverter, I'm a well known SMA fan around these parts so thats how I would do it, opinions vary a lot on this one though and I dont have any experience with Solaredge, good luck with it, cheers

[TimeOrMoney]

Howdy TimeorMoney, if you dont have shade issues and its ground mount I would be going with a string inverter, I'm a well known SMA fan around these parts so thats how I would do it, opinions vary a lot on this one though and I dont have any experience with Solaredge, good luck with it, cheers

Thanks for your reply. Can you tell me why you are a fan of SMA? Or perhaps you can point me to one of your threads extolling the virtues. I know they've been around a long while.

[8.4]

How hot does your location get? If it's super hot, I think I would prefer a shaded area to protect the electronics. I don't think heat and electronics make for good combo, but that's just my opinion. String inverter does have alarming when something is wrong, but you have to check (at least in my case) it daily to make sure it's functioning. With the other, even if one panel is down the others are working so you would probably not have to check as often.

[solar pete]

Well we have been using them here in OZ for about 8 or 9 years now, have tried other brands and found them to be the most reliable and SMA are a very good company to deal with if there is a problem, they are I think the only company (in OZ anyway) that actually pay the installer to replace a inverter if necesary, it goes some thing like this.......customer rings in.. hey I've a red light on the inverter, (us) oh dear can you tell me what the error code is,...yep its blah blah...(us) ok I will send on of the sparkys out to replace it...now thats not always the case it depends on the error code. Just trying to convey they are a good comapny to work with

[MikeInRialto]

Yes with smaller systems cost i very close. The way i decided was micros = any one fails and the rest of the system still produces - cost, if not under warranty, is a just over $200 vs. String system = 3 points of failure (a single panel, an optimizer, or the invertor itself... any one goes bad and the whole system goes down).

[solar pete]

Yes with smaller systems cost i very close. The way i decided was micros = any one fails and the rest of the system still produces - cost, if not under warranty, is a just over $200 vs. String system = 3 points of failure (a single panel, an optimizer, or the invertor itself... any one goes bad and the whole system goes down).

Howdy MikeinRialto, thats not quie right, you will generally have at least 2 strings on a string inverter, if one panel in a string fails it does not affect other strings

[schmoot]

You mentioned future expansion. This could be accomplished by oversizing the string inverter over your current requirements. Of course you will need to look at the efficiency and startup voltage of the inverter you select to see if this would negatively impact your current array. I am in the process of installing solar, and I have opted for Solar Edge, and oversizing the main inverter, to allow for future expansion at a substantial savings over a micro inverter system.

[deyounte]

Howdy MikeinRialto, thats not quie right, you will generally have at least 2 strings on a string inverter, if one panel in a string fails it does not affect other strings

Hi Mike, Hi Pete,

I'm more of a microinverter kind of guy, but don't the bypass diodes for most panels allow the string to limp along with one or two panels with issues? Or are we just talking about the case where the whole panel goes O.C. and kills the string that way?

Tim D,
Melbourne, FL

[TimeOrMoney]

How hot does your location get? If it's super hot, I think I would prefer a shaded area to protect the electronics. I don't think heat and electronics make for good combo, but that's just my opinion. String inverter does have alarming when something is wrong, but you have to check (at least in my case) it daily to make sure it's functioning. With the other, even if one panel is down the others are working so you would probably not have to check as often.

Not real hot here normally, I'm at 5000 ft. The area behind the panels, being on the shade side, won't get as hot as rooftop, so I'm not worried for Microinverters. Plus they are easy to get to, unlike rooftop. If I used a central inverter, it would be located away from afternoon sun, so no problem there either.

I'm doing a DIY(I'm an electronics engineer) install. When I look at "kit" prices, I'm seeing the same prices(within $100) for all three solutions. So far, the Enphase feels the best to me, although the communications package is extra. What I like so far is easy design, easy install, no DC switch and fuse box, no scary high voltage DC, simplicity and monitoring.

[TimeOrMoney]

You mentioned future expansion. This could be accomplished by oversizing the string inverter over your current requirements. Of course you will need to look at the efficiency and startup voltage of the inverter you select to see if this would negatively impact your current array. I am in the process of installing solar, and I have opted for Solar Edge, and oversizing the main inverter, to allow for future expansion at a substantial savings over a micro inverter system.

When I was looking at the Solar Edge, I thought I saw some communications issues with getting data from the power optimizers depending upon distance from the inverter? I've done so much reading I've lost the link on that, so I may have it wrong.

[solar pete]

Hi Mike, Hi Pete,

I'm more of a microinverter kind of guy, but don't the bypass diodes for most panels allow the string to limp along with one or two panels with issues? Or are we just talking about the case where the whole panel goes O.C. and kills the string that way?

Tim D,
Melbourne, FL

Yeah, if one panel has a partial fail the rest of the string should still work, if one panel fails the string should still work. The string inverters (SMA does) gives you a read out on the display of the two strings, so if you have say a 5kW system with a SB5000 it displays the wattage and voltage of each string, so with 2500 watts (name plate wattage) on each string all panels facing the same direction it is obvious if there is an issue, both strings figures should be very close to each other, interestingly everytime I look at the SB5000 set up in the office the strings are never identicle but that I believe is due to the varying wattage of the panels, as a panel that is sold as a 250watt panel may in fact be a 254watt panel or a 253watt panel etc

[thejq]

Not real hot here normally, I'm at 5000 ft. The area behind the panels, being on the shade side, won't get as hot as rooftop, so I'm not worried for Microinverters. Plus they are easy to get to, unlike rooftop. If I used a central inverter, it would be located away from afternoon sun, so no problem there either.

I'm doing a DIY(I'm an electronics engineer) install. When I look at "kit" prices, I'm seeing the same prices(within $100) for all three solutions. So far, the Enphase feels the best to me, although the communications package is extra. What I like so far is easy design, easy install, no DC switch and fuse box, no scary high voltage DC, simplicity and monitoring.

Yes, if it's DIY, microinverter is probably the easiest to install. You just have to make sure your wiring is thick enough to accommodate the higher current. Being on the ground, replacing them should be easy too. SolarEdge setup has a few more parts, and also has high voltage DC which you need to be careful with. The communications issue can be easily solved with WiFi extender(s).

[jflorey2]

Thoughts? Experiences? Other considerations?

One issue is that it is VERY difficult to get backup power with microinverters. With the SMA TL-US inverters it comes for free (at least while the sun is out.)

[solarix]

Between our work, our leasing company's, and doing service work, I've installed all the different inverter brands and have come to the conclusion that on solar systems trying to reach 25 year reliability, that what counts with inverters is durability, durability, durability. We install the best (SMA) and service the rest. SMA is no contest the most reliable in my experience. The only reason I'd use anything else is in difficult shading applications - and even there, its not as much of an issue as it used to be. And its always better to eliminate the shade than mitigate it.