Re: [RE-wrenches] Heinz 57 off-grid array - What should I do with the solar modules?

[Allan Sindelar]

Bob, What you are describing is not as uncommon as you may think - it's kinda how things were often done by off-grid homeowners: adding modules as needs grew over the years. I have told many homeowners in years past that yes, you can add additional PV modules at any time - these were what were available at different times. It used to be that with rare exception, all modules had 36 cells and were nominally 12V, so they could all be paralleled for additional input current as long as the input conductors could handle it. Nowadays it looks pretty funky, but it was somewhat common in early years. Your client was actually smarter than most to buy modules in pairs, rather than singles. The Photowatt PWX500s are well-made, non-UL 47.5W 12V modules sandwiched between two glass sheets. They were the first (European) offering of Photowatt US, aka Matrix in Albuquerque, now defunct. About 2001 vintage. No safety issues, well-made, just never listed. The Photowatt PWX1000s were more or less two of these in one frame, I think. Most were UL-listed, as I think they were manufactured here. The KC120s are well known and have been discussed here. Modules from the late 90s may be defective - low output. Kyocera replaced some for me (I wasn't the original installer) under warranty, but the 10-year warranty has since run out, so I dunno. Golden Genesis was who bought Photocomm, before it was itself bought by Kyocera. A short-lived bastard stepchild of the Joseph Coors Brewing Company. Could be Astropower 75s, could be Photocomm Solavolt; likely not Kyocera, as I don't think they ever made a 75 - just 60s and 80s. There was a private-labeled Solarjack 75 (part of pump systems) but I don't know who the manufacturer was (Joel will, of course...). Usually when we fully upgrade a system we keep the existing array. Like Ray sez, if the racking was good it might be worth simple rewiring - all are good older modules and all are reasonably compatible, although you're stuck with 24Vnom with all of these. The "turd in the punchbowl" (so to speak) is the new 2hp turd grinder. You didn't say what the existing inverter is, but it doesn't matter - it won't work. Even an old SW4024 is not likely to start and run 2hp - and you'd need a step-up transformer. Two SWs will handle it, if you can find a mate and stacking cable for it. I'd replace the array, upgrade the entire system (except batteries) with a new big honking inverter, and warn them they're looking at about 20 grand. Part of this is that the turd pump is a big load, best run at 48Vnom, which the array can't do. Or they can figure out a different way to grind their poop and the job is much simpler. I can't suggest how much simpler without more info on existing equipment. Allan Allan Sindelar Allan@positiveenergysolar.com NABCEP Certified Photovoltaic Installer EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com Bob Clark wrote: Wrenches:   We were called to assess the status of an off-grid system that is not the worst I have seen, but it comes close.   I have some preliminary thoughts about system redesign, but would like to hear from the Wrenches about the array.   Givens: We will not install anything unless it is to code.  It is obvious that none of the existing system was installed to code. We will use the existing 24V battery bank consisting of 8, Trojan L16s.  The batteries are still “relatively fresh.” Pump is a Franklin pump ½ hp 115VAC.  The CFs dim when the pump starts. New load will be a GRINDER PUMP FOR SEPTIC = 2HP, 15amp (240 or 120VAC – more than likely it will be 240V pump) – Another light dimmer! Modest daily electrical load (estimate no more than 600 WHr/day; 25AHr) – they are very good at managing their electrical use.   Solar array – to keep or replace? 8 solar modules – a Heinz 57 mix of older modules - 2 Photowatt PMX500 (Are these modules UL listed?  There did not appear to be a rating label on the back.) wired in series, 2 Kyocera KC120-1 wired in series, 2 Golden Genesis PV-75 wired in series, 2 Photowatt PW 1000 12V-24V internally wired for 24V wired in parallel with the other modules strings – all of these modules are wired in 5 parallel strings for approximately 34.2Vmp and 20.4Imp, ~695W (STC).   Oh, and they need a new mounting structures for the modules.   Should I try to work with these modules or advise the customer to start over (any modules that are not UL listed will have to go)?   What is a good “rule of thumb” for a ratio of PV watts to battery bank capacity per day of autonomy?   Thanks for your ideas.   Bob Clark SolarWind Energy Systems, LLC   _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org

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