Depending on the light conditions, that could be a normal reading. I've
seen the MPPT voltage approach battery voltage in low light/ cloudy
conditions. If this was in full sun, I would start isolating the
strings, and see what their individual performance is. Also as
mentioned, it could be a loose connection, so a thermal imaging camera
is great to "see" those bad connections. That should be a good system,
I don't know of any problems with the Shell modules from that time period.
Ray
Remote Solar
On 10/2/17 9:21 AM, Steve Bell wrote:
Hi Bill,
The original Voc of the array was probably about 91 volts, the original Vmp
of the array was probably about 68 to 70 volts. The 58 Vmp from the array
still seems somewhat low. I would check for bad/corroded connections
causing a voltage drop while under load.
Best Regards,
Steve Bell
On Mon, Oct 2, 2017 at 8:27 AM, frenergy <[email protected]> wrote:
Off-gridders,
Checked in on a 13 year old system and something caught my
eye. Yes, everything is 13 years old. First off: PVs: 14 (7 strings of 2
PVs each), Shell 150's, batts: HUP 845 AHR, 48 volt system, MX60 CC. So
the MX60 was reading (mid day) ~1500 watts or ~27 amps (somewhat low for
the array but acceptable considering age, soiling, tilt, etc. Regardless,
Volts "IN" were 58, batt volts were ~53.5. This info was taken from the MX
display.
For PVs that have an MPPT rating of 45.5 volts ( X 2 per
string = 91V), that 58 volts seems especially low. Normal?? Possible one
string is pulling down the rest? Feedback welcome.
Bill
Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
www.frenergy.net
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