SB 7000 US - Fan cut in temperature

[DanP]

Hello,

I've googled until I can't google anymore.

Hopefully someone on here knows this answer:

At what inverter temperature should the fans come on for an SB7000-US inverter? I just installed a DYI ground mount system with 36 230w panels/3 string system and today was the 1st day with
net metering installed. Was checking the inverter temperature parameter from the data stream (rs485). Is 140 degrees high? Ambient temp was about 75-80.
Plan on doing a fan test tomorrow.



Thanks for any input
Dan

[J.P.M.]

Is the free air flow to the fans blocked or restricted ? Are the fans operating ? Is the inverter in a confined space ?

The manual doesn't seem to list a normal or max. operating temp. for the heat sink. I'd call SMA and ask them what a normal or expected temp. difference between ambient air and heat sink temp. might be.

My inverter isn't an SMA and is not fan assisted, but normally the heat sink runs about 25 - 30 C. or so above ambient, depending on input to the inverter unless I'm supplementing nat. convection cooling with forced air cooling. Then it runs ~ 18/20 C above ambient air temp. 35+ C. delta T may be OK for your SMA, but it seems maybe a bit high to me.

As you've probably done, I've rooted around and can't find anything from SMA on what they think an OK heat sink operating temp. or what an OK operating temp. diff. heat sink to amb. air might be.

[DanP]

JPM,

Thanks for the reply. The air flow is not blocked. Fans did not come on. Which lead me to wonder if the fans should have at those temperatures. In my case it was running 35-40 C above ambient today. SMA manuals are lacking on that minor detail.

Dan

[DanP]

Found the answer:
Default T-Start-Fan is 70[FONT=sans-serif]

[J.P.M.]

JPM,

Thanks for the reply. The air flow is not blocked. Fans did not come on. Which lead me to wonder if the fans should have at those temperatures. In my case it was running 35-40 C above ambient today. SMA manuals are lacking on that minor detail.

Dan

You're welcome. Still seems like kind of a high temp. before turnon. Any chance/thought on lowering it ?

[inetdog]

You're welcome. Still seems like kind of a high temp. before turnon. Any chance/thought on lowering it ?

Since the 70c is listed as the default value, it appears that you can lower it. You may need to get an administrative password/code from your dealer if your normal login cannot change it. As I recall the SMA fans are particularly noisy (not variable speed among other things) so they set the cut-in temp high to minimize noise complaints for indoor mounted systems.

[DanP]

Inetdog,

Thank you for the suggestion, I may lower the valve. The inverter is located in an outbuilding/barn 120 feet from home, so the only thing that will be annoyed by fan noise will be squirrels.

As for dealer, that's out of the question. I'll have to call SMA as I designed, permitted and installed myself. The local solar dealers in my area are.... well I can't type what they are without getting banded. I didn't plan on DYI'ing this but they kind of forced the issue.

Anyway, very happy with the project. Now I gotta find another project to work on.

. Patellis - Array photo small.jpg

Trees on the ground were taken down because they were dead from pine boring beetles.


Thanks again
Dan

[J.P.M.]

Since the 70c is listed as the default value, it appears that you can lower it. You may need to get an administrative password/code from your dealer if your normal login cannot change it. As I recall the SMA fans are particularly noisy (not variable speed among other things) so they set the cut-in temp high to minimize noise complaints for indoor mounted systems.

Maybe the higher set point gets the MTBF's closer to warranty period on an overly robust design. Seems like backwards logic, but who knows these days. Maybe cheaper than design change. I've seen dumber logic.