Comparison of systems, anyone using ReneSola?

[Kenstl]

I had received a couple of quotes for systems. The sizing difference is due to one contractor being more conservative with the application as they felt the larger size was pushing the limits for approval with the electric company as they do not allow systems greater than 80% of need? After rebates and all, there is a .30 per kWh difference between the two systems. I have read what I could on the panels involved but frankly, I am wondering if you can really over analyze the panel differences. For me, I am probably at the point that the cost differences are enough that I would probably not even do the system at he higher cost due to the longer payback period but I also want to assure myself that I am installing a system that will be productive and not a lot of equipment issues. Does anyone have any systems installed with the ReseSola Virtus II panels and inverters that they could give me some feedback?

[B]System 1
PV Modules: ReneSola Virtus II 156 Series Polycrystalline 255 Watt Modules.
Inverters: ReneSola Replus-250A Microinverters.
PV System Mounting Equipment: SnapNrack Series 100 Roof Mount System.
PV System Monitoring Equipment: Micro Replus Gateway Monitoring System.
- 8.67 kW estimated installed power capacity
- 34 modules and 34 microinverters.

Cost:8.67 kW at $2.95 kWh total of $25,570
Rebate $2.00 ($17,340)
30% federal ($2,469 )
----------------
Out of pocket $5,761 $0.66 kWh


[B]System 2
PV Modules: Suniva Model SW260 Mono/2.5 frame.
Inverters: Enphase M215 micro inverters.
PV System Mounting Equipment: Unknown.
PV System Monitoring Equipment: web based monitoring.
- 8.67 kW estimated installed power capacity
- 34 modules and 34 microinverters.

Cost: 9.62 kW at $3.40 kWh total of $32,700
Rebate $2.00 ($19,240)
30% federal ($4,038)
----------------
Out of pocket $9,422 $0.98 kWh

[Volusiano]

Is there a reason why you want microinverters instead of string inverter? Do you have shading issue?

Going with string inverter may lower your system cost a little bit more. Also, will you be able to get both part AND LABOR warranty for your micro-inverters (I heard that Enphase has stopped giving out labor warranty)? If you can't get labor warranty on your micro-inverters, repair/replacement can become a big issue since it may require multiple (up to 34) trips up to the rooftop and possibly dismantling the array to get to the problem unit -> high labor cost x multiple trips due to having 34 micro-inverters. If you live in a hot climate area, the failure potential due to higher heat on the rooftop is going to be higher, too.

[Kenstl]

Is there a reason why you want microinverters instead of string inverter? Do you have shading issue?

Going with string inverter may lower your system cost a little bit more. Also, will you be able to get both part AND LABOR warranty for your micro-inverters (I heard that Enphase has stopped giving out labor warranty)? If you can't get labor warranty on your micro-inverters, repair/replacement can become a big issue since it may require multiple (up to 34) trips up to the rooftop and possibly dismantling the array to get to the problem unit -> high labor cost x multiple trips due to having 34 micro-inverters. If you live in a hot climate area, the failure potential due to higher heat on the rooftop is going to be higher, too.

Thanks. Good point on the inverters. The warranty is on the part only and not labor, but it is a 25 year limited warranty so it should last longer than a string inverter? I do not have any shade issues to be worried about so it would probably be an option. I liked the idea of the being able to monitor the system with the micro inverters, but there could be additional costs involved if they need to be diagnosed or replaced. I will have to check and see what the cost difference would be, if they can be mounted outside, etc.

[Volusiano]

Thanks. Good point on the inverters. The warranty is on the part only and not labor, but it is a 25 year limited warranty so it should last longer than a string inverter?

From what I hear, the Enphase microinverters use electrolytic capacitors just like the string inverters, so I don't see why it should last longer than a string inverter, especially when it's up there on the roof top running hotter than the string inverter down on the cool ground in the summer time. From that point of view, their 25-year part only warranty without labor warranty is meaningless to me. Also, the fact that they used to include labor in the warranty but have now not included it anymore makes you wonder why they change their mind, hm?

If you still really want to have a distributed system even though you don't have a shading issue (maybe your panels have different orientations, etc that may require different tracking circuits), another option is to use the power optimizers for each panel but still have the string inverter down on the ground, like what Solar Edge offers. You still have a distributed system with the risk of mulitple points of failure up on top of the roof. But at least the Solar Edge power optimizers uses a lot less circuitry just enough to do the MPPT job without the DC to AC inverter on the rooftop, and they still offer both part AND labor warranty on their stuff.

I still would recommend string inverter for simplicity's sake and lower cost if you don't have shading issue or different panel orientations on the roof. Putting any kind of electronics up on the hot rooftop without good enough justification is just not worth the risk if you ask me.

There are options to monitor the whole system using string inverters, too. That's nothing exclusive to microinverters or power optimizer-based systems. You just can't monitor the performance of the panels individually that's all.

[silversaver]

If there's no shading issue, avoid micro inverters. You don't want people walking on your roof in next 20 to 25 years.

[AZHIGH]

Good point about walking on the roof. I like the idea of micro-inverters but you could increase your point of failures 30 fold depending on how many panels you have. Not saying they will fail but, there are more parts that can fail in the system. On the upside each panel can be individually monitored and each can produce at their max capacity regardless of shading etc. Micros add more expense. I have been told that here in AZ they are not recommended. Not sure I believe that at all. We met with one company that has a great reputation and they only install micros. So that says a lot.

We sign our contract tomorrow. Can't wait for the install!

[Volusiano]

I have been told that here in AZ they are not recommended. Not sure I believe that at all. We met with one company that has a great reputation and they only install micros. So that says a lot.

If the micros are Enphase, and we know that Enphase doesn't include labor warranty on their micros, the question you should ask this company is whether they will give you their own labor warranty on the micros or not? If not, why would you want micros unless you really need them? If yes (this company offers labor warranty even though Enphase doesn't), then I would make sure to get it in writing, then ask myself if I'm really convinced that they're going to be around in the long run to really honor their labor warranty or not? If all they do is installing micros like you said, I'd be doubly worried because they'll have such a high liability in paying out of their own pocket for labor warranty in replacing micros in the future that they'll be doomed to be out of business sooner rather than later.

No matter how reputable a solar installer is, I wouldn't count on a solar installer to be around past 10 years time to honor anything. I'd bank on a reputable manufacturer to be around past 10-20 years, but I wouldn't bank on any solar installer for that duration. If they last that longer or longer, then great. But I wouldn't hedge my bet on it because the industry is very competitive.

Here's a link from an actual solar installer in SoCal offering their opinion on why they think micro-inverters are not such a good idea unless necessary for shading or multiple orientations.

[russ]

We met with one company that has a great reputation and they only install micros. So that says a lot.

All that says is they are a foolish company. Anyone married to a particular idea is making a mistake a good part of the time.

[Naptown]

ONe of the larger companies around here and the eastern part of the US is Astrum. They have been using exclusively Enphase for a while. They are also giving a 20 year labor warranty with each system. If the Tax credits are not extended after 2016 the odds of the being around for long afterward are probably not good unless electricity costs here jump dramatically. As all intelligent business owners are they are incorporated probably lease most of their equipment and facilities.
When the big money of installs goes away and they are replacing inverters for free they will probably not last long. It's hard to stay in business doing free repairs with no money coming in.
So in short in no way should anyone take more than a 5 or 10 year warranty from an installer seriously.