Mounting inverter in Phoenix: Garage or Outside?

[Volusiano]

I talked to my installer and they have no experience with SolarEdge, never used or installed it. They have done micro-inverters and he said it's probably similar on the panel install side. He did say micro-inverters need some sort of extra ground that's not needed when doing a string inverter? Is the same true for SolarEdge?

Price wise, the SolarEdge inverter and 48 optimizers would be about $5,400 going by online prices. He said the Fronius inverter is $3,500, so looking at +$1,900 minimum. I'm sure they would upcharge it a bit but shouldn't be more than +$2,500 I wouldn't think vs the old Fronius install. But, the SolarEdge has built in wi-fi monitoring *I think* where as with the Fronius it's an additional $800 and it's a must for me, so really the net additional would be +$1,100.

I don't know if you're with SRP or APS. If you're with SRP, they have overall system level monitoring already on their website for daily generation, consumption and net data, and hourly generation data and hourly net, although the hourly net only shows positive net and not negative net for some reason, and there's no hourly consumption.

I was planning to buy a $400 Bluetooth monitoring hardware box up front, but there was some compatibility problem with the box so I ended up returning it. Then I saw all the data already on the SRP website and that was good enough for me, so I'm glad I didn't shell out extra $ to buy monitoring hardware to begin with.

But if SolarEdge has monitoring already built-in to their system, then that's cool, but otherwise, you may find SRP data to be good enough for you. The novelty of being able to monitor things will wear off on you after a while and you won't be monitoring as closely and as often as you would in the beginning anymore.

I think with your situation, the SolarEdge solution would be very effective. You not only have shading issues but also have panels all over the roof with all kinds of orientation and pitches. So that would make your case idea for a SolarEdge application.

I wouldn't touch the Enphase microinverters with a 10-foot pole if I were you simply due to the fact that you live in Phoenix. It's hot enough on the roof already for Power Optimizers like SolarEdge. No need to shove microinverters up on the hot roof on top of that. SolarEdge took the right approach there to still put the string inverters on the ground. They also claim that their string inverter can handle many/any string size configuration and don't have string size limitation that the traditional string inverter has. It's probably worth the extra money going with SolarEdge instead of doing multiple traditional string inverters in your case.

[HX_Guy]

I have 44 panels (11KW system) all in one place on the roof (not spread out like yours). My installer ran all the wires inside a single conduit down through the attic to the other side of the house where the garage is. From there, this single conduit goes into the combiner box, and from there split out into the 2 inverters, then the inverters go into a single breaker box before going into a dedicated meter for the solar system, then to an ON/OFF switch box before going into the main circuit panel.

He said per code you can only run 5 wires through a conduit? Something along those lines?

[HX_Guy]

I don't know if you're with SRP or APS. If you're with SRP, they have overall system level monitoring already on their website for daily generation, consumption and net data, and hourly generation data and hourly net, although the hourly net only shows positive net and not negative net for some reason, and there's no hourly consumption.

I was planning to buy a $400 Bluetooth monitoring hardware box up front, but there was some compatibility problem with the box so I ended up returning it. Then I saw all the data already on the SRP website and that was good enough for me, so I'm glad I didn't shell out extra $ to buy monitoring hardware to begin with.

But if SolarEdge has monitoring already built-in to their system, then that's cool, but otherwise, you may find SRP data to be good enough for you. The novelty of being able to monitor things will wear off on you after a while and you won't be monitoring as closely and as often as you would in the beginning anymore.

I think with your situation, the SolarEdge solution would be very effective. You not only have shading issues but also have panels all over the roof with all kinds of orientation and pitches. So that would make your case idea for a SolarEdge application.

I wouldn't touch the Enphase microinverters with a 10-foot pole if I were you simply due to the fact that you live in Phoenix. It's hot enough on the roof already for Power Optimizers like SolarEdge. No need to shove microinverters up on the hot roof on top of that. SolarEdge took the right approach there to still put the string inverters on the ground. They also claim that their string inverter can handle many/any string size configuration and don't have string size limitation that the traditional string inverter has. It's probably worth the extra money going with SolarEdge instead of doing multiple traditional string inverters in your case.

I'm with APS. And I know for some the novelty of monitoring would wear off...me, I have two Nest thermostats that I've had for a couple of years and I log in every couple days still to see how much the A/C ran. I really like the monitoring stuff so it is a must for me.
I found that the SolarEdge does come with monitoring built in, but not wi-fi. It has an ethernet port so I'd have to run a wire from my router to the inverter, but it shouldn't be a big deal as my router is probably about 20' away from where the inverter will be.

I've actually found out a lot more info on the SolarEdge product, talked to their tech support for a bit. Install wise, its the same as doing a regular 1 string inverter except plugging in the optimizer at each panel and grounding each optimizer to the railing (which I think the panels have to be ground as well, right?).

The system works a bit different than I thought. I was figuring that each panel is literally on it's own and independent of the others and its sort of true. Each string still need a minimum voltage to operate, so you can't have a string of 1 or 2 panels for example. I'm a little fuzzy on this but they said that the inverter needs 360v min per string and it will raise the voltage up to 60v per panel in order to reach that voltage, so you need a minimum of 6 panels, though they recommend 8 min to have a little cushion. When talking about shading, it means that a string has to be setup so that at least 6 panels are never shaded in that string...so you can have a string of say 18 panels, and if 12 are shaded, those other 6 will still produce full power. If 13 are shaded, then you lose the whole string. They did say that even the full shaded panels will still produce something, but very minimal, maybe 10% of full output if lucky due to ambient lighting. Obviously still much more ideal than any other setup where if you had a string o 18 panels and 12 were shaded, you could kiss that string goodbye. Most likely even if only 2 or 3 were shaded that whole string would be gone.

[inetdog]

He said per code you can only run 5 wires through a conduit? Something along those lines?

Not true, but close enough to pass for correct.
What happens is that any time you run more than three current carrying conductors (not counting grounds and unused neutrals) through a conduit you may have to reduce the allowed amperage that the wires can carry based on their size.
If there are enough wires in the conduit that could force him to use larger, more expensive wires. If the wires get big enough he might then need to install a larger conduit just to hold them.

Bottom line: It is not prohibited, but to do it he might have to use wire and conduit sizes that he does not normally stock, causing him some discomfort.

[HX_Guy]

Heh, yeah he probably meant he can't run more than 5 wires through a conduit.

[Volusiano]

I'm looking at the electrical plan that they submitted for my 11KW 44 250W panel system, and they have 4 strings going to 2 inverters (2 strings of 8 to the SMA 4KTL and 2 strings of 14 to the SMA 7K), for a total of 8 #10 Cu wires, 2 #8 Cu ground wires, totalling 10 wires, half of which goes through a 3/4" conduit and the other half goes through another 3/4" conduit.

But in reality, they ran 9 #10 AWG wires (4 black 4 white and 1 green) into a single 3/4" conduit from the roof down to a splitter box into the 2 inverters before the combiner. Inspector passed it OK, so I don't know what the deal is. There seems to be room left in that single 3/4" conduit even with 9 wires. Seems like you can run up to a dozen #10 wires inside before it gets crowded.

[HX_Guy]

So your paperwork said that they were going to actually run two separate conduits but they actually just ran all the wires through a single conduit?
Would make sense as to why they didn't charge extra for doing two inverters vs one (that that's still surprising as two inverters will cost more than a single bigger inverter). Inspectors must have been in a good mood that day. Imagine if he said nope, denied until you run another conduit.

[HX_Guy]

Haven't heard back from my installer on the SolarEdge quote, he's probably thinking I'm insane by this point, but I'm hoping they are reasonable in their pricing. They may not be since they have never done these and now they have to spend time to learn how to install them and set it up.

Heck I'm willing to get up there and install the actual optimizers myself...all they require is grounding to the rail using a provided stainless steel star washer. Thats it. The rest is just plugging in the connectors into each other and the panels into the optimizer, and it's all male/female connectors so you can't mess them up.

I'm really on the SolarEdge bandwagon though, seems ideal and I don't see any downsides at all, aside from additional cost.

[Volusiano]

So your paperwork said that they were going to actually run two separate conduits but they actually just ran all the wires through a single conduit?
Would make sense as to why they didn't charge extra for doing two inverters vs one (that that's still surprising as two inverters will cost more than a single bigger inverter). Inspectors must have been in a good mood that day. Imagine if he said nope, denied until you run another conduit.

Although they ran a single conduit from the roof down to the ground, they did split the wires inside a square junction box and 2 separate conduits come out of that box with each going to an inverter. So technically they can say that THOSE 2 conduits out of the junction box are the ones in the drawing.

Another consideration is that it may be code in your city but not necessarily mine. It's hard to tell.

Like I said, even with 9 #10 AWG wires inside that 3/4" conduit, it looks like there's plenty of room for a few more (I opened up the junction box to peek inside). So I fail to see why code would limit the # of wires going through a conduit, as long as the conduit can comfortably hold all the wires inside with room to spare. If you have too many wires, then just get a bigger size conduit that can hold them all. Unless you only have smaller size conduits in stock.

Before they started my installation, they did say that they gotta check with my city first to see if they could run a conduit through the attic, instead of outside on the roof. They said all cities have different requirements and even their codes change often so they always call and double check before they perform the work to make sure they don't have to redo anything unnecessarily at inspection time.

It took a crew of 4 guys (the foreman is the electrician) 2 days to install my 11 KW 44 panels 2 inverter system with the combiner and derating the main panel. They didn't have the 175A breaker so they had to use the 150A breaker they had in stock. I was kinda pissed about that but the owner told me in writing that if I ever need more than 150A, he'll change it out with a 175A free of charge.

[silversaver]

That's pretty much BSing. Regardless of 1 or 2 inverters, they are running same amount of wires from top down. Agree?

But...... why are you trying to save little money and be their first test sample? Ouch

[HX_Guy]

I don't agree that it's the same number of wires. And it's certainly not the same amount of conduit if code is followed.
If you do two inverters, I was told they need to run two conduits from the rooftop to the inverters. They would also have to run the wires all the way down from each string I believe since each string would be on it's own MPPT input.
With a single inverter, they could bring all the wires together on the roof top into a combiner box and then just run 3 wires through one conduit down to the inverter. A lot less wires and 1 less conduit.


The savings are pretty huge because of the way I can pay for the system (barter). If they can install a regular string inverter type setup, they can install the SolarEdge. Hell, I could install the SolarEdge if they just do the mounting and install the actual inverter.


I just spent a few hours crunching numbers comparing the single 11.4 Fronius inverter vs two PowerOne inverters vs SolarEdge based on my estimate of how much production would be lost from the shading in each setup. My results came out:

Single 11.4 Fronius Inverter: 17,381 kWh per year
Dual PowerOne Inverters: 19,094 kWh per year
SolarEdge: 19,423 kWh per year

So I would get 2,042 kWh or 10.5% more production out of the SolarEdge setup vs the single Fronius. Dollar wise, at 14.5¢ per kWh, that's $296. Say it costs +$3000 to go with Solar Edge vs the Fronius, it's about 10 year ROI. I'm hoping it will be less than $3000, more like $2000.

The dual PowerOne is a difference of 1,713 kWh or $248/year and the extra cost is +$4000, so looking at a 16 year ROI.

BTW, if there were zero shade issues, the estimates production for the system would be 20,281 kWh/year so I'm looking at a loss of 15% with the single Fronius inverter or 5% with the SolarEdge. Numbers are based on 12kW system, derate of 0.84 with 12 panels facing east and 36 panels facing south.

[silversaver]

My neighbor just finish his solar installation today with 1 conduit top down 2 inverters.

I wont trust those shade calculator....... I have eperience shading issue. It is easy to remove the tree, but not your neighbor's roof.

[HX_Guy]

Different areas have different code and it also matters on the number of strings I believe as well.

And I didn't use a shade calculator. I figured it manually using my computer model and taking each panel and calculating how many hours per day it would get full sun. Should be pretty spot on and possibly even better than my calculation as even the shaded panels may produce something, whereas if it was even partly shaded, I figured zero production.

[russ]

My neighbor just finish his solar installation today with 1 conduit top down 2 inverters.

I wont trust those shade calculator....... I have eperience shading issue. It is easy to remove the tree, but not your neighbor's roof.

Removing the neighbor's roof shouldn't be all that hard - might cause a lot more problems than one can handle though. Just email www.removearoof.com - seems the guy's address is the state pen though.

[silversaver]

Different areas have different code and it also matters on the number of strings I believe as well.

And I didn't use a shade calculator. I figured it manually using my computer model and taking each panel and calculating how many hours per day it would get full sun. Should be pretty spot on and possibly even better than my calculation as even the shaded panels may produce something, whereas if it was even partly shaded, I figured zero production.

Seriously, you know nothing about shading. You keep asking questions and then keep telling people the answer. using 1 inverter for all you solar arrays is not your installer's fault, it is the guy who wants to keep saving money and asking for trouble. You probably better off burn the money.

BTW, reading your threads is fun. Remind me the story "Man of La Mancha"