[RE-wrenches] Shedding ice

Mon Jan 16 12:34:38 PST 2012

We are currently in Culebra installing a pv system with two Classic 200's.
Its a great controller to set up and install. While snow melt is not
important here, i did notice after using the setup wizard that it mentions
future new features with the snow melt function being one of those
mentioned. There is no mention of it in the guide but i haven't had a
chance to look through the included dvd. It seems to me it is still in the
planning stage and I will be in line to buy a couple for my own system
when it comes out.

Daryl DeJoy
NABCEP certified installer
Penobscot Solar Design

> Mark,
> I believe the Midnite Classic has this feature built in. Check with them.
> David Katz
>
> From: Mark Dickson [mailto:Mark at OasisMontana.com]
> Sent: Monday, January 16, 2012 10:00 AM
> To: 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> Subject: [RE-wrenches] Shedding ice
>
> I recall a conversation a while back about the possibility of
> â€œreversingâ€ the current in a solar module to increase the cell temp
> enough to shed ice/rime.  To follow-up, has anybody been successful at
> this?  I am guessing, if so, it would entail, removal of diodes,
> increasing PV and battery capacity and some way to sense the ice at the
> very least. . . It sounds good in theory, but I am skeptical as to whether
> it will work in reality. . .
>
> Best regards,
>
> Mark Dickson,
> NABCEP Certified Solar PV Installer â„¢
> Oasis Montana Inc.
>
> ________________________________
> From: re-wrenches-bounces at lists.re-wrenches.org
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan
> Sindelar
> Sent: Monday, January 16, 2012 10:52 AM
> To: re-wrenches at lists.re-wrenches.org
> Subject: Re: [RE-wrenches] Request for Gennie Recommendation
>
> Wrenches,
> I very much appreciate this ongoing thread, thank you.
>
> This actually feels like one of those "damned if you do, damned if you
> don't" scenarios. The system is six years old, poorly designed and
> installed. Two SW5548s, most likely chosen in order to run a 2HP
> conventional well pump for this manufactured home. Thirty-two L16s in four
> strings, in two unvented battery boxes in an unheated shed at 7800'.
> 1.66kW of PV plus an H40? wind generator, in an area not known for great
> wind resource. The inverters either were never programmed correctly or
> lost programming the first time a battery was replaced, so the batteries
> never got above default 57.6V and were never equalized. When the L16s
> started failing, the installer instructed the owners to replace individual
> batteries, over and over until 17 of the 32 had been replaced, one or two
> or four at a time. With a continuing stream of failing cells, each time
> the well pump came on the voltage dropped to "must start" and the
> generator came on. With default programming, the inverters would charge to
> 57.6V (if the batteries would get up there - not sure if they ever did),
> then go through the two-hour absorption, then shut off and soon the cycle
> would repeat.
>
> The installer put a Link-10 in the home, but without a prescaler, so it
> couldn't work on a 48V system. So he tapped off of part of one string. All
> monitor programming was at default settings, so the system monitor had
> been useless to the homeowners since installation. This was designed and
> installed by someone in business doing wind and PV since the 1980s. His
> website claims he is "the most experienced contracting company in the
> Southwest specializing in electric/electronic installation, service and
> repair of independent, remote or utility integrated power generation power
> supplies. We provide electrical engineering design, specializing in
> on-site electrical power generation and related control systems." This is
> some mighty poor work.
>
> Our immediate "rescue solution" was to string together 16 of the
> replacement batteries, program the inverters to corrective EQ, show the
> homeowner how to change inverter settings, and replace the Link-10 with a
> TriMetric with prescaler, guessing at 500 amp-hours. At first this
> appeared to have failed - the battery voltage rose quickly under charge
> and then fell just as quickly. But we later learned that this actually
> worked, as they told us that after running a long corrective EQ, the
> batteries came back and the generator ran far less. But then the existing
> generator failed to start; apparently just worn out, and they're in bad
> shape.
>
> We plan to add about 2-2.5kW of array, although we have no load profile
> from them yet. The existing array is on two poles. The (original) smaller
> array of 8 Sharp 80W 12V modules is shaded during winter by the larger
> array of 6 Sharp 170W modules during the mornings. The larger array is
> shaded by both a juniper tree on winter mornings (until after 11 am) and
> by the power equipment shed on winter afternoons (after 3 pm). The ground
> is frozen now, so we have no easy way to either increase the array of move
> the existing arrays out of where they shade each other.
>
> They have two SW5548s, so need around 15kW at 7800' to run the inverters
> at full capacity. The unknown is that we don't yet know what size the new
> battery bank will be; my SWAG is about 1,000 a-hr in a single string of
> industrial cells. Together the SWs can charge at 120A, so 1,000 A-hrs
> would be a good match. You are correct that the generator run time will be
> greatly reduced once the array is increased, the batteries replaced, and
> their loads reduced through customer education. But they need a gennie
> right away, as their PV and wind can't keep up and the system is shutting
> down. I'm hesitant to recommend a generator of less than industrial
> quality, given their experience to date with two residential units. And
> any good generator has a 4-6 week lead time.
>
> What would you do in this situation?
> Allan
>
> P.S. Chris Mason, your website doesn't jive...I went to
> www.cometsystems.co<http://www.cometsystems.co> and got a site that said
> "Comet Systems Ltd. is a Certified Reseller for Xorcom PBX products and
> Ruckus Wireless." Doesn't appear to have anything to do with either PV or
> generators. Can you enlighten us?
> Allan Sindelar
> Allan at positiveenergysolar.com<mailto:Allan at positiveenergysolar.com>
> NABCEP Certified Photovoltaic Installer
> NABCEP Certified Technical Sales Professional
> New Mexico EE98J Journeyman Electrician
> Positive Energy, Inc.
> 3201 Calle Marie
> Santa Fe, New Mexico 87507
> 505 424-1112
> www.positiveenergysolar.com<http://www.positiveenergysolar.com/>
>
>
>
> On 1/16/2012 9:03 AM, Dave Palumbo wrote:
> Chris,
>
> It would be very helpful if you quote â€œrun hoursâ€ rather than
> â€œyearsâ€.
>
> For example we have seen:
>
> Inexpensive small generators (generally not worth rebuilding) 300 to 500
> hours. These are gasoline models of various brands and Generac LP gas
> models. 3kW to 10kW in size typically.
>
> Honda gasoline generators 2,500 hours and then rebuild.
>
> 10kW Kohler water cooled diesel gen set still operating within specs at
> 9,600 hours (rebuilt after 5,500 hrs). This has been in service for 16
> years, the first 4 years without inverter/battery system, and another 6
> years before the client had us add a PV array to the system. Since adding
> the PV array the generator has run 200 hours per year.
> All are in off-grid service and loaded at 65% MAX continuous (see some
> surges higher than 65%, typically run at 60%, or below, of rated power).
>
> David Palumbo
> Independent Power LLC
> 462 Solar Way Drive
> Hyde Park, VT 05655
> www.independentpowerllc.com<http://www.independentpowerllc.com>
> NABCEP Certified PV Installer
> Vermont Solar Partner
> 24 Years Experience, (802) 888-7194
>
>
>
> From:
> re-wrenches-bounces at lists.re-wrenches.org<mailto:re-wrenches-bounces at lists.re-wrenches.org>
> [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Comet
> Systems
> Sent: Monday, January 16, 2012 10:21 AM
> To: Howie at catamountsolar.com<mailto:Howie at catamountsolar.com>;
> RE-wrenches
> Subject: Re: [RE-wrenches] Request for Gennie Recommendation
>
> The Generac QT and commercial units do not come with an ATS, you can buy
> just the bare machine or have a complete solution designed for your load.
>
> The Generac residential machines are good machines, as long as you
> understand the intended use. We install lots of them. They are only
> designed to be used occasionally, for residential backup. We get customers
> who want to run their business all day on a 10KW residential generator and
> are disappointed that the generator won't last ten years. They are a
> cheap, lightweight and cost effective solution for people who get
> occasional outages.
>
> If your customer has worn out two generators already, then (s)he needs to
> pay for a commercial level product. A 22KW QT is not that expensive and
> will last ten years at a substantial load factor. If you give me more
> information on the location, load factor and loading, I can have
> engineering recommend a solution for you.
>
>
> --
> Chris Mason
> President, Comet Systems Ltd
> masonc at cometsystems.co<mailto:masonc at cometsystems.co>
> www.cometsystems.co<http://www.cometsystems.co>
> Cell: 264.235.5670
> Int: +1305.767.2094
> Skype: netconcepts
>
>
>
>
>
>
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