SunnyBoy or Fronius Primo inverter? Deciding between systems...

[NewHere]

Hi, I am completely new to solar and considering proposals from a couple of contractors. One is proposing a 3.1 kW system of (9) 345W SunPower panels with a SunnyBoy inverter located on a south facing roof. The other is proposing a 4.2 kW system of (14) 305 kW LG panels with a Fronius Primo 5.0-1 inverter, with panels located on a south facing roof plus on a basically flat roof adjacent to it. The LG system is priced about $1500 more, but gives me an extra kW of power, which I am pretty sure I will use. On the other hand, the SunPower panels have a better warranty and higher efficiency, with less degrading over their lifespan. But the economics seems to work out in the LG system's favor--quicker ROI. Am having a hard time sorting out the variables. Both seem to be top brands. Any thoughts? Any advice that anyone would like to offer would be much appreciated. Thank you!

[Living Large]

Hi, I am completely new to solar and considering proposals from a couple of contractors. One is proposing a 3.1 kW system of (9) 345W SunPower panels with a SunnyBoy inverter located on a south facing roof. The other is proposing a 4.2 kW system of (14) 305 kW LG panels with a Fronius Primo 5.0-1 inverter, with panels located on a south facing roof plus on a basically flat roof adjacent to it. The LG system is priced about $1500 more, but gives me an extra kW of power, which I am pretty sure I will use. On the other hand, the SunPower panels have a better warranty and higher efficiency, with less degrading over their lifespan. But the economics seems to work out in the LG system's favor--quicker ROI. Am having a hard time sorting out the variables. Both seem to be top brands. Any thoughts? Any advice that anyone would like to offer would be much appreciated. Thank you!

What is the cost of each of the systems?

[solarix]

I've installed both and was not impressed with Fronius - don't understand why the top cover on the inverter is made of plastic. Used to use Fronius for the larger sizes (7700, 10kW) but now that SMA has come out with the larger sizes, I see no reason to do Fronius. If you are installing solar panels that last 20-30-40-50 years, do you want to compromise on inverter reliability?

[J.P.M.]

If you have not yet done so, I'd suggest starting with how much electric energy you use, then understanding how you pay for it. Then, decide what makes sense to you from an economic and lifestyle perspective.

Run PVWatts and get some estimates on size that meets your determined goals.

Get some estimates from established electrical contractors who have been around a long timer and sold solar for at least 5 years.

Get your roof inspected and serviced as needed. Cheap insurance.

Compare prices on a $/installed Watt basis. You'll find Sunpower is about 15 - 25 % or so higher on that basis and therefore less cost effective than most any other reputable equipment, even after consideration for the alleged lower degradation and "better" warranty.

Avoid placing panels in the horizontal position. Annual output will be less and panel fouling (dirt) will probably be more of a problem.

Expect most string inverters to last 10-12 years with reasonable it to the rest of the system and somewhat protected location.

[sensij]

I've installed both and was not impressed with Fronius - don't understand why the top cover on the inverter is made of plastic. Used to use Fronius for the larger sizes (7700, 10kW) but now that SMA has come out with the larger sizes, I see no reason to do Fronius. If you are installing solar panels that last 20-30-40-50 years, do you want to compromise on inverter reliability?

Hmm... does a plastic cover would hurt an inverter's life? SMA inverters are expected to last something like 10-12 years. Are you suggesting that the Fronius Primo's are not likely to last that long? Those inverters were just launched this year... it seems a bit soon to be trashing their long term reliability.

[NewHere]

What is the cost of each of the systems?

Roughly $4.10/W for SunPower panel system and $3.35W for the LG panel system.

[NewHere]

I've installed both and was not impressed with Fronius - don't understand why the top cover on the inverter is made of plastic. Used to use Fronius for the larger sizes (7700, 10kW) but now that SMA has come out with the larger sizes, I see no reason to do Fronius. If you are installing solar panels that last 20-30-40-50 years, do you want to compromise on inverter reliability?

Thanks for your input.

[Naptown]

Hmm... does a plastic cover would hurt an inverter's life? SMA inverters are expected to last something like 10-12 years. Are you suggesting that the Fronius Primo's are not likely to last that long? Those inverters were just launched this year... it seems a bit soon to be trashing their long term reliability.

Reality is the inverter will be replaced half way through.
Therefore why worry about a plastic cover that is UV inhibited

[NewHere]

[/QUOTE]
If you have not yet done so, I'd suggest starting with how much electric energy you use, then understanding how you pay for it. Then, decide what makes sense to you from an economic and lifestyle perspective.

Thanks. My 5-year average is about 5600 kWh/year, though I may be able to get it lower. Am working on calculating break-even points for each scenario, but finding it hard to predict variables like whether electricity prices will rise (and if so how much?), and what the SREC market will do. But those are probably questions for another thread....

Run PVWatts and get some estimates on size that meets your determined goals.
Yes--very helpful site, thanks!

Compare prices on a $/installed Watt basis. You'll find Sunpower is about 15 - 25 % or so higher on that basis and therefore less cost effective than most any other reputable equipment, even after consideration for the alleged lower degradation and "better" warranty.
Any thoughts on SMA SunnyBoy vs. Fronius Primo? That Fronius model seems to be fairly new and I couldn't find any reviews.

Avoid placing panels in the horizontal position. Annual output will be less and panel fouling (dirt) will probably be more of a problem.
Interesting....had not heard that before.

[solarix]

Here in the dry desert southwest, plastic is a no-no. UV-stabilized doesn't do much. Those black UV wire ties? last about 6 months... even in the shade. Its not a UV thing. The resins in the plastic just evaporate. I don't know about the new Fronius, but the top on the old ones is going to crack and get it wet inside. Poof - "the smoke will get out".

[J.P.M.]

Any thoughts on SMA SunnyBoy vs. Fronius Primo? That Fronius model seems to be fairly new and I couldn't find any reviews.

I'm of the opinion that a well designed system will include a well designed and thought out choice for an inverter, its interface with the balance of the system and its location. I'd expect a good string inverter to last 10-12 years. I have no working experience with either of those inverters except to remark that of the 60 + installs in my HOA, there have been no failures among inverters of all types/mfgs., but that's only over 6 years.

Avoid placing panels in the horizontal position. Annual output will be less and panel fouling (dirt) will probably be more of a problem.
Interesting....had not heard that before.[/QUOTE]

See PVWatts for the effect of tilt/azimuth on performance.

As for fouling on horizontal panels: Tilted panels get washed to some degree by the rain. The tilt takes the rain and some or most (but probably not all) of the accumulated dirt with it. Horizontal panels do not have that advantage. Some things, among many, that can and do happen to horizontal panels: Depending on the nature of the dirt, it will sit on a horizontal panel. To make matters worse, the dirt tends to crust/cake as it gets wet, goes nowhere, then solidifies and sticks/cakes up when the water evaporates. The next rain adds the accumulated additional dirt to the cake, etc. Standing water that may freeze also may not be too good for panel integrity after many freeze/thaw cycles.

Finally, panels often have a raised lip around the perimeter that will act as a dam at the lowest part of an almost, but not quite horizontal panel, effectively allowing a mud section at the "low" edge, the mud shading part of that panel. On balance, horizontal panels are probably not a good choice, not even at/near the equator.

I'm sure there are other drawbacks.

[Keepsake]

I have both SMA aka Sunny Boy and Fronius. Needless to say the Fronius has already failed on me. Still under a 10 year warranty from Fronius, but not !! Their staff on the phone had diagnosed error codes 516 and then 443. They say it needs a board replacement. They want me to pay and buy the entire inverter and won't send out a replacement board. I don't have the reserve on my c/c so I am out of production and s.o.l. DON'T BUY FRONIUS.

[peakbagger]

My Fronius got zapped by a utility issue. I called them on Monday and they sent a reconditioned unit that day and had one 3 days later. My friend had a utility issue that was knocking his inverter off line. They worked with him and gave him access to factory functions in the inverter to do a work around. I dont have experience with SMA.

[Keepsake]

Got two Fronius IG5100 that are 5 years old. To date they have both failed. Company 10 year warranty is useless. Nobody local (Im in Florida) will service them. And they wont exchange with end user without exorbitant collateral on a credit card. DO NOT waste your time with Fronius.

[DanS26]

My experience with Fronius has been first rate. I run two Fronius 7.5 kW units for ~5 years now. Two minor warranty issues....both fixed within days.

But really...individual anecdotes are meaningless in the scheme of things. Both Fronius and SMA are first rate inverter companies, I don't think you can go wrong with either choice.