Inverter placement - opinions please!

[Jtt777]

I’m getting my solar system installed on a south facing house. The Tesla design has the inverters being installed on the west side of the house. Plenty of shade. The east side of the house is however where my circuit breakers and meter are.

My last Tesla install got aborted because of an panel selection error. However during their time here the installer wanted to place the inverters on the east side for ease of install. He was worried about the sunlight and heat on the inverters and said he’d call the design group before install. I recently had the install team call them and they said they were okay to install there. Warranty would still apply and it should still work.

However, the disadvantage I’ve been reading is that the inverters may be less efficient in the heat and die sooner. The advantage is there is no need to route a wire in the attic across our entire house and the west side of the house stay “clean”. I am not sure how messy all the wiring might be going into and out of the attic.

What are your thoughts on the placement of the inverters? I have no basement option and the garage is on the east side however it is a small garage and I think these boxes protrude a decent bit.

 

[Silicon Desert]

My opinion is simply based on my electronics design consulting, and software design with SMA (one of the larger inverter manufacturers in Germany). Whenever possible I always suggest keeping inverters in a shaded area away from the sun and direct heat. Heat is the biggest enemy of electronics (aside from power surges). Many inverters are only warranted and rated to last 15 years to 20 years anyway.... depends on the manufacturer. As a side note, I don't like the inverters that have fans and gigantic electrolytic capacitors (much larger than some).

As far as being less efficient, not really. The difference in efficiency loss due to extra heat is minor by comparison. Most every inverter out there is at least 95% efficient and typically 97% or higher. It's the heat build up inside the inverter that is the biggest factor on life expectancy.

 

[Shygar]

I put mine on the east side, but that was by far the easiest anyways. I would think heat would be a problem in the summer, even in north NJ (I used to live near Paramus). If your breaker box is on the east side, seems like that would make more sense anyways. Would it really be that bad to run the wire through the attic? You have to run a wire back to the breaker box anyways right even if you install on the west side.

 

[Silicon Desert]

If your breaker box is on the east side, seems like that would make more sense anyways. Would it really be that bad to run the wire through the attic? You have to run a wire back to the breaker box anyways right even if you install on the west side.

Good point. I totally overlooked the fact that his breaker box and meter is on the East side. To me that is a slam dunk decision. East side even if the DC wires from the modules have to run a longer distance.

 

[Darwin]

I would put the inverter in a shaded location, unless wire routing is prohibitive. This will extend the life of the inverter electronics. displays and controls and improve efficiency. Routing wires through the attic should be relatively simple. For you it sounds like this would be the west side - so I may be mis-interpreting the question based on reading the other responses here.

If there's a location on the east (sunny?) wall a little closer to your breakers and meter (say over a fence in the back yard) where you would be able to install a shade screen, that's an option too.

 

[NuShrike]

Can't just install an awning over the East-side "sunny"-side installation?

East-side should only get sunrise-to-noon sun, but the peak of heat is generally noon-to-sunset.

 

[Shygar]

I actually like that my powerwall gets sun until noon so that maybe it helps warm it up a little bit. Not that it gets that cold here.

 

[Jtt777]

Thanks for the tips everyone. An awning of the east side could fix this since the sun is basically overhead but not sure if it is that easy to build one and then it will block my access to the backyard.

putting the inverters on the west side would keep them coolest but I would have the longest run back to the breaker box.

 

[nwdiver]

putting the inverters on the west side would keep them coolest but I would have the longest run back to the breaker box.

North NJ is gonna be a walk in the park compared to what these inverters are designed for. Even on the hottest and sunniest day I doubt your internal temps exceed 120F. They're designed for 140F.

 

[Silicon Desert]

North NJ is gonna be a walk in the park compared to what these inverters are designed for. Even on the hottest and sunniest day I doubt your internal temps exceed 120F. They're designed for 140F.

That's probably right. I don't know what the weather is like up there, but sure sounds cold. Actually, the inverters I have designed are spec to run up to 70 C (158 F), so even better. Still, I prefer to put inverters in the coolest possible location if installation cost is not a factor.

 

[Silicon Desert]

Can't just install an awning over the East-side "sunny"-side installation?

East-side should only get sunrise-to-noon sun, but the peak of heat is generally noon-to-sunset.

yup that is another good solution and some people do that..... a short over-hang awning over the inverter to prevent direct sunlight. Although keep in mind that the sunny side of the house still tends to be the hottest because the sun heats up the wall and other building materials around the inverter.

 

[Vines]

The east side imho, assuming you have an overhang of some kind. East sides are usually cooler than west sides, ignoring the fact that you have shade on the west side. One thing you can do is to place the inverter as high on the wall as is reasonable. We also try to install in a shady area when possible, but its not super significant if your temperatures on the inverter never reach 120 degrees.

I might have a different opinion if you had no eaves on your roof, but my thinking is that the hottest part of the day is afternoon, and so morning sun isn't nearly as bad, because the ambient air is much cooler.

In the summer, the sun angle is pretty high overhead. When the sun is directly overhead, and probably even from 11 am onward the eaves should still shade the inverter. In the other seasons, the ambient temperature probably isn't as high.

Also, figure its $500 extra in install costs to cross to the other side of the house. A brand new 7600W Solar edge inverter can be had for about $1500. I really don't think that you will be looking at a 30% worse lifespan to be on the east side compared top the west side. However energy harvest may be lower.

You haven't specified what inverters they will install, but some inverters will automatically derate themselves past 120 degrees. This is one of the ways that they maintain long lifespan. If you install on the east side, you can probably see if any clipping happens on your hottest days of the summer, compared to the cooler spring and fall days. If you do see power deration on the hottest days, and its significant, you could probably mitigate it with some small shade block.

 

[Darwin]

My SolarEdege 7600H inverter temperature can hit 120F on a 70 degree day (5.6kW system in Phoenix). I imagine this delta would be even greater if my system were larger or if my inverter wasn't fully shaded.

I'm not sure you'll be able to tell if your inverter is derating due to heat. From my observations, derating with the 7600H may progresses gradually as temperature increases. I haven't observed abrupt clipping in the output power data, even when the inverter temperature approached 150F. I have though observed a noticeable increase on the power output graph after positioning a fan to blow over the heat sink when the inverter temperature was 135+, so I do believe the inverter was derating at the time.

I would also check with your installer on price if there is a more optimal location for the inverter than at the meter. My installer didn't make a price distinction on inverter location, but then again attic runs for my home are pretty simple.

 

[nwdiver]

My SolarEdege 7600H inverter temperature can hit 120F on a 70 degree day (5.6kW system in Phoenix). I imagine this delta would be even greater if my system were larger or if my inverter wasn't fully shaded.

I'm not sure you'll be able to tell if your inverter is derating due to heat. From my observations, derating with the 7600H may progresses gradually as temperature increases. I haven't observed abrupt clipping in the output power data, even when the inverter temperature approached 150F. I have though observed a noticeable increase on the power output graph after positioning a fan to blow over the heat sink when the inverter temperature was 135+, so I do believe the inverter was derating at the time.

If you have monitoring it should report derating. The SMA inverters I monitor report everything else.

WOW... Solar Edge starts derating at 122F... I can see why they put 5.6kW on a 7.6kW inverter... But I don't see how derating is possible in your case since fully derated your inverter would STILL be 6.4kW and if your inverter is derated your panels would be too so your 5.6kW array would be <4.5kW.

Hmmm... SMA starts to derate at 113F... always thought it was ~140F... Looks like 140F is just the upper operating temp.

 

[Darwin]

I don't see how derating is possible in your case since fully derated your inverter would STILL be 6.4kW and if your inverter is derated your panels would be too so your 5.6kW array would be <4.5kW.

That's a good question - and the SolarEdge de-rating technical document is a great find. I had not seen that.

The document states that "All SolarEdge products operate at full power and full currents up to a certain temperature, above which they may operate with reduced ratings to prevent device damage." All conjecture on my part, but I would guess that the output de-rating always occurs once the peak temperature is reached, and that the curves shown in the document may be simplified for communication purposes and only show the response curve when the inverter is at its rated kW production.

If the purpose of de-rating is to prevent device damage from heat, it would make sense to me to begin de-rating any time the inverter reached its critical temperature, regardless of how much power the inverter is producting.

 

[eml2]

I have though observed a noticeable increase on the power output graph after positioning a fan to blow over the heat sink when the inverter temperature was 135+, so I do believe the inverter was derating at the time.

I have a SolarEdge 7600A with 9.24 kW DC PV panels. I also tried to use a fan to blow over the heat sink but didn't observe any increase in power output. Here was the graph on 7/19/18.

I started the fan around 1 pm. The inverter temperature immediately dropped from ~146F to ~104F. However, there was no change in power output. It was not clipping either because the voltage stayed at the normal range. When it clips, it will jump to ~450V. The ambient temperature around that time was ~80F.