Xantrex: Inverter Operating Temperature range

magneto · **Posted:** Fri Apr 27, 2007 3:47 pm GMT EthGMT

I have a 4.6KW system using sunpower SPR-4000x inverter, rebranded Xantrex GT3.8. I was told that there was a bad run of them and I might need my inverter replaced. A week later the inverter stopped working. And the company that installed them replaced it. By this time I had GT-View running and I started monitoring my system. What happens to the inverter if it operates outside of the â€œOperating Temperature Rangeâ€ (OTR) for a long time? Can they burn out? Iâ€™ve been looking at the logs and found that the inverter is above the OTR 2.5 to 4 hours each day (150-172 degrees). The efficiency of the inverter was 94% on the first day, 92% the second and now itâ€™s between 89% and 90%. I put a fan on it to keep the temp no higher than 110 but the efficiency is still around 90%. Should I get the inverter replaced again?

Solar Guppy · **Posted:** Fri Apr 27, 2007 4:01 pm GMT EthGMT

Where are you located and where is the inverter located , ie outdoors in the sun?

Thoses tempatures are above the units maximum, I am surpised the derating didn't kick in, as I beleive 70C is the threshold and your almost 78C.

I have never heard of units failing due to heat ..

As for the efficiency reported, I suspect due to your extreme tempatures the calibration of the unit s off at a minimum ... more details please ,

like operating voltage, ambient tempatures, units locations, is the unit in power or thermal limits. what ever is happening, its NOT the norm.

magneto · **Posted:** Fri Apr 27, 2007 5:48 pm GMT EthGMT

The inverter is in my garage. I'm not sure whether the unit is in power or thermal limits. don't knowwhat that is.

Here is a small sample of the log before I put the fan in.

Code:

Date         Time      VDC   DC Amps   MPPT   DC Pwr   AC Pwr   Eff   VAC   AC Wh   HS Tmp
4/24/2007   12:18:45   278.6   15.15   278.3   4208   3749   89.09   237.2   12748   158
4/24/2007   12:19:45   275.6   15.54   276.2   4283   3822   89.24   237.9   12812   158
4/24/2007   12:20:45   275.6   15.57   276.2   4280   3818   89.21   238.6   12876   158
4/24/2007   12:21:45   275.6   15.54   276.2   4283   3822   89.24   238.6   12939   158
4/24/2007   12:22:45   277.4   15.42   277.4   4284   3822   89.22   237.2   13003   158
4/24/2007   12:23:45   276.8   15.45   276.9   4282   3821   89.23   237.9   13067   158
4/24/2007   12:24:45   276.8   15.48   277.4   4285   3827   89.31   238.6   13130   158
4/24/2007   12:25:45   277.4   15.42   278     4282   3825   89.33   239.3   13194   158
4/24/2007   12:26:45   278     15.39   278.6   4287   3832   89.39   239.3   13258   158
4/24/2007   12:27:45   278     15.45   278.1   4284   3824   89.26   239.3   13321   158
4/24/2007   12:28:45   278     15.39   278     4286   3831   89.38   237.6   13385   158

Solar Guppy · **Posted:** Fri Apr 27, 2007 7:04 pm GMT EthGMT

Your running the inverter flat out ... you have a 3800 watt inverter running at noon time at 3825 watts ... that is its maximum

What is it like in the garage? what is the Outside/Inside tempatures? how many panels and of what model?

Your array is also putting out near STC power, even before solar noon ...

You can look at the GT-View display at this time, you will probably see the DC power limit and possibly the thermal derating message in the status box ( right hand box in GT-View )

mike90045 · **Posted:** Fri Apr 27, 2007 7:22 pm GMT EthGMT

magneto wrote:

I have a 4.6KW

What brand / model / quantity are your panels? They are really putting out power. Got any location or install pics ?

magneto · **Posted:** Fri Apr 27, 2007 7:26 pm GMT EthGMT

I have 21 Sunpower SPR-220-WHT 3 strings of 7 mounted on the roof south facing. I'v noticed that on GT-View "DC power limit" is on for 2 to 4 hours depending on cloud cover. It was cooler inside the garage than outside but I know it will get warmer as summer approaches. As far as the inverter running flat out ... I did ask the installers about that since according to their proposal I would be getting more production during the summer months and how that was going to work out if the inverter is already maxed out.

Wennfred · **Posted:** Fri Apr 27, 2007 7:32 pm GMT EthGMT

Ouch, Thats pretty HIGH Temp !!! One thing I learned over my many years messing around with Electronics, Heat reduces the life of any electronic gear. Heat is also the enemy when it comes to keeping tolerances stable. I have been using my two GT3.8 Inverters since 15 April of this year and when I saw the temp on one of them hit 128f, I freaked out and installed two 5 inch A/C fans under the rafters in the Garage facing down at each inverter. These fans I got at Radio Shack. These 2 fans are connected to an Appliance Timer which I got at the Home Depot. They come on at 7:30am and shut down at 7:30pm. Now my Temps so far haven't hit over 103f. I recommend cracking the bottom of your garage door to let in some cool air. Also I do not park my car in the garage when I arrive during the day because the engine will raise the heat levels in the garage.

Timer with both fans hooked up, note the white plugs on the left side.

Close-up of Fans

2 Fans on top facing Inverters

Fred

Solar Guppy · **Posted:** Fri Apr 27, 2007 7:34 pm GMT EthGMT

I looked up the forcast for Oxnard CA ... 62 for a high, If you near the water, which by google maps looks like your 1-4 miles away from the Pacific Ocean, that would explain the cool temps ...

Since your ambient is BELOW STC standard of 77 degrees, good chance your array will run at or above its STC rating of 4600 watts, which leads me to believe your inverter choice is to small

Your system should really use a GT5.0, other wise your wasting a good 1-2kw/day minimum.

And if your going to run inside a garage, yes, keep a fan on it ... there are some suggestions on how best to do this in other recent posts

As for your current inverter I would press your installer to exchange it for a GT5.0 or what ever the relabled SunPower one is called ... 3.8 is to small for your array and cool location

Wennfred · **Posted:** Fri Apr 27, 2007 7:35 pm GMT EthGMT

When I first hit my Max Limit at around 4010, I called my Designer, he told me since it was for only a few seconds or minutes, thats no problem, those peaks will come from the edge of the clouds etc. But if they were locked in for 2 to 4 hours, then the system isn't balanced correctly. It sounds like you have way too much load on that Inverter. Get them back out there and install a GT5.0 for sure.

Fred

Wennfred · **Posted:** Fri Apr 27, 2007 7:44 pm GMT EthGMT

Solar Guppy, are the Limits on the GT3.8 are the DC Watts or the AC Watts?

Fred

Xantrex: Inverter Operating Temperature range

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