Author Topic: Did I purchase the wrong voltage surge protector?  (Read 110 times)

qrper

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Did I purchase the wrong voltage surge protector?
« on: September 30, 2019, 01:35:28 PM »
gang...

Sometimes getting old sucks. I think I screwed up, again!

Going to re-wire the classic 150 into one of the midnite solar disconnect boxes. the Baby box was simply too small and when the larger circuit breaker, they won't fit

So I ordered in a surge protector with the other new pieces parts. It's the MNSPD115

My system is 48Vdc.

However the input is 90ish Vdc. Later in the evening when the batteries are at float, the input voltage hovers around 104 or so.
After reading the specifications, it appears that the 115 SPD won't be happy on the PV input side.

Did I screw up? Or can in indeed use the MNSPD115 on the PV input to my classic?

Mike
System one: 7kWp with Trina 250 W panels wired for 90 Vdc. Via Classic 150 to 16-6 V U.S batteries. Trace 5048 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.

Vic

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Re: Did I purchase the wrong voltage surge protector?
« Reply #1 on: September 30, 2019, 02:40:19 PM »
Mike,  assume that you have looked at the following:
http://www.midnitesolar.com/pdfs/spd_frontBack_display_web.pdf

Would guess that "MCOV",  is Maximum Continuous Operating Voltage.
MCOV may have some temperature dependency,   though.

Also,   have you looked at the SPD Topic on this Forum (?):
http://midniteftp.com/forum/index.php?board=13.0

A number of Threads there,   have expert advice on voltage selection.

The PV Voc,   as you know,   will increase as your ambient temperature decreases.   Voc,  of course,   by definition,   is with no current flow,   but,   still your PV voltage will rise in cold temperatures.

FWIW,   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

boB

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Re: Did I purchase the wrong voltage surge protector?
« Reply #2 on: September 30, 2019, 11:32:44 PM »

Well, you might want to wait for an official answer BUT if the TMOV I am looking at in our parts list is correct, the minimum turn on voltage (1 mA) for this SPD SHOULD be  184V DC and maximum at 225V DC.

So, if this is correct and you are using a Classic 150, 184V should be high enough for you to use it even on your PV input.

1mA is where they rate these things to just start turning on and you know it's not going to typically be THAT close to 184V.  Probably closer to 200VDC.

You can call in and ask or I can just ask at work tomorrow to make sure what I'm looking at here is what we are really using in that SPD115

boB
K7IQ

qrper

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Re: Did I purchase the wrong voltage surge protector?
« Reply #3 on: October 01, 2019, 11:55:13 PM »
Thanks, bob,

Iam going to connect it to the PV side

Will keep everyone informed

Mike
System one: 7kWp with Trina 250 W panels wired for 90 Vdc. Via Classic 150 to 16-6 V U.S batteries. Trace 5048 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.