I missed the part about limiting the design to a 75 w module. That's
only a C30 charge rate, which I think is too low for the battery size.
That's apparently a 5 day at 80% DOD criteria; very 90s. Haven't they
heard about $1/w PV?
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
On 12/31/2013 1:43 PM, Exeltech wrote:
Hey Mr. Ray ...
Aren't you just a gluttony of good info! You're darned handy to have around.
I wasn't aware of the Midnite unit. I'll have to scope it out.
I'm concerned with Eric's mention of the bid requiring a 120AH battery (~1.5 kWh) .. and
only 75W PV. Hopefully their loads are small, of short duration .. and they have plenty
of sunlight. The latter sounds iffy from Eric's statement about "cloudy days".
BZ Products makes a 25A MPPT with a built-in digital voltmeter. Perhaps it could be a
two-in-one option for Eric?
Stay warm.
Happy New Year to you and yours ....
Dan
--------------------------------------------
On Tue, 12/31/13, Ray Walters <r...@solarray.com> wrote:
Subject: Re: [RE-wrenches] Higher LVR to force full re-charge in small OGPV
systems
To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org>
Date: Tuesday, December 31, 2013, 2:01 PM
I'll chime back in on a few points:
To MPPT or not: It all gets down to the budget: I find the tipping point to be around 250 to 400 watts. My small systems usually don't have MPPT, and as soon as I get into more than a pair of
modules, I'm using the cheaper 60 cell modules with MPPT. I like Blue Sky's
new PWM 30 amp controller that also includes a digital meter.
Temp compensation: it all depends on the temperature variation. If its warm year round, just program the charge settings lower, and as Dan said KISS.
Metering: Midnite's Battery Capacity Meter was specifically designed for the African market. Very simple LED "smiley face, frowny face" reading, It's cheap, and it actually does a decent job of
tracking SOC. Its not a Trimetric, but its way better than a volt meter too.
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760
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