| Author | Message | ||
| Jim (Jim_in_california)
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Hey guys, check this out - it's a European very high efficiency rooftop AC powered by either 12v or 24v DC: http://www.dcairco.com/ There appears to be at least one US distributor: http://www.espar.com/htm/aircondition.htm If I'm reading those power requirements right, you could run two of the 9,000btu critters off of a single Honda EU2000i genset(!) and have some wattage left over for battery charging...? Basically set up the genset to pump up the batteries with a good charger, then draw the ACs right off the house battery bank. It would also be simple to run at least one and probably two off of a decent size alternator and get over-the-road cooling that way. And with NO inverter inefficiencies at all. I'll get prices from Espar soon... | ||
| Jim (Jim_in_california)
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Oh, another thing: remember what I've been saying about small cheap inverters (Samlex 600watt pure sine for $300 and similar) for "electronics only" use? Well if your ACs are DC <grin> then you simply DO NOT need that big undercarriage monster inverter anymore, or any inverter bigger than 1000w or so (the "kitchen use" for the coffee pot, microwave, etc). So even if these "DC Airco" critters run $900 a pop, the inverter savings alone would make 'em worth it. | ||
| James Maxwell (Jmaxwell)
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There appears to be some potential there except for the part that says no starting wattage. That I don't understand. I would also have to question the effectiveness of 2 of these units for cooling even a well insulated 35-40 bus. The efficiency appears good from the raw numbers but I have to question whether or not they have the capacity needed. No way in hell would I run them from the starting batteries as they suggest. | ||
| Brian Brown (Fishbowlbrian)
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Some thoughts: Jim, I don't think the majority of busnus use an inverter for over-the-road A/C (air cond.). The loads and amps are pretty huge. What your units would allow for is a much smaller genset, since the AC (alternating current) loads don't involve A/C. The 12v/24v DC A/C models you cite, if tenable, would call for three units to give comparable cooling to two 15k BTU AC-driven units. Then, the DC loads have to be addressed. A 12v unit running a 430w load would have pretty substantial cabling requirements to combat voltage drop and heat. Running three units off an alt. calls for a BIG alt AND a BIG converter or two when you're plugged into shore. Trade-offs, I guess. Your find is pretty interesting, nonethless. Please keep us posted on prices and availability. Thanks, BB | ||
| Craig (Ceieio)
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I wonder if the split system might make a nice dash air solution while driving? I need to figure something in that department. I would like to avoid running the genset on moderately warm days while tooling down the highway. Could be interesting to watch this technology develop. | ||
| James Maxwell (Jmaxwell)
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Craig: Just for comparison. The usual dash air system operated from an engine driven compressor of the Japanese variety is capable of 3-3.5 ton and is usually connected to an 15-18k btu evaporator unit in the dash. The Cruise-Air units when used as dash air are 15k btu. I have to seriously doubt that the 9k roof unit there would work for the front compartment of a bus unless you partitioned it right behind the front seats. The split system they have, in addition to being prototype in nature, would be even more insufficient, not to mention that the power consumption figures they list appear to be conflicting. I just don't see enough information on their site to make a true informed judgement, other than the stated capacity, which is decidely deficient, regardless of whatever other claims they make. If they are truly as efficient as some of their numbers would make them, they have to have a SEER rating well above 20, which is in itself, amazing. I would really be interested in some more specs on them just as something to see, but since I'm not in the market for them, I'm not going seeking it. | ||
| Jim (Jim_in_california)
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Part of it depends on climate I guess...I think two 9000s might do OK on a well-insulated 35' in *northern California* although I'll be the first to agree it'd be marginal. SoCal or Arizona or someplace, no. ----------- The info on using the starter batteries is keyed mostly to the trucking crowd, which have big starter batteries and alternators already. What else...these DO have "low battery protection" so that they can't drain a battery to it's dregs. ------------ Another implication of these puppies: there are some VERY efficient small diesel engines available, some down in the 3.5hp or less range. One of those rigged through a good alternator to do the equivelent of 2000watts or so of power would get killer fuel efficiency; there's a whole network of "ultra-greenie off-grid enthusiasts" who have been delving into the possibilities of those setups; see also: www.utterpower.com ...for a good starting point. I don't see having to run big heavy power cables to the A/C units as being that big an issue. You only have to run one, as the frame ground is the other. Battery cable can be had in bulk lengths. I guarantee that will be cheaper than buying mega-inverters. ---------- Here's a thought: 430watts draw means you could power one of the 9000s with three 160watt solar panels worth about $700 each. Now granted, that's a BIG-ass upfront cost for only mediocre gain, and that's not counting the minimum $350 for an MPPT solar charger. But if the goal is to spend the money up-front to be able to live with NO fossil fuels for significant periods...it would be an interesting concept. Put another way, it's a way of placing a bet on the economy, that there might be a really serious rise in oil prices (leading to gasoline/diesel at $15/gal or more) leading to a period of economic depression and hyperinflation. Go google the term "peak oil". There IS a lot of blathering and fearmongering going on with this subject but some elements do make sense...just as one example, why is China building mega-hydroelectric dam projects at such a furious rate they're affecting world prices in concrete? There are numerous other examples of goverments (including ours) acting in fashions compatible with a fear of serious economic rough times (and low oil) ahead. Well, a solar array is good for 20+ years. A spare controller/charger isn't too expensive; a really quality battery bank good for 20+ years (HUP or similar) is almost as pricey as the solar panels. But...if your money is going to be borderline valueless in two to five years, such an expenditure now makes good sense. And if the economy does NOT tank like that, hey, you still have some pretty killer off-grid gear  . Is a $5000 "bet" like that a good bet if you have the cash now? I'm increasingly convinced that it is. | ||
| James Maxwell (Jmaxwell)
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Jim: All sounds good w/ a couple of exceptions. As u know I live in N. CA and even N. of you. I have on many occasions seen 118*, and for several days at a time, and for several hours per day in excess of 115*. At any rate, do not expect peak performance from those 3 solar panels for more than 7.5 hrs. per day on the best days of the year for solar. For this area, you can count on approx. 4 months of optimum solar performance and don't ever figure them at 100% of capacity. My experience with them is approx. 75% of rated capacity under ideal conditions, and it seriously and rapidly degrades from there. I have 500 watts worth on my Neoplan roof and in all honesty I would rather have a wind generator. I invested the 2k in them primarily so I could prove to a couple of friends that they were'nt worth a sh... Thank God for that nice reliable 24/7/365 Isuzu dsl genset. Supply of crude is not the major factor behind current prices; speculation is. $15 a gallon is a perfect example of the rampant speculation fueling costs. Which Pres. 1st told us we were going to run out any yr. now? I think that was 2 or 3 before the Pres. that told us the "Great Russian Bear" was going to get us; using those ox carts, and the dozen or so automobiles they had that run, they had for transportation. And it's about time China builds something on that order, well overdue, and especially if they want to move into the 21st Century before it is over. Hurricanes in Florida effect the price of plywood nationally, but that does not spell impending doom. Bottom line. I can buy a whole lot of KWatts of electricity and a couple of effective roofairs for what you are going to spend on all this speculative crap to power your 2 under-sized AC's. But, it's your money, and you should spend it to get this economy spiked, if for no other reason. | ||
| Jim (Jim_in_california)
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James: I realize most of what you're saying, but also recall that those four months of peak solar period is also the times when you'd need A/C the most. Wintertime, I'd be using propane for heat. Which solar controller have you been using, and does it have MPPT? I have a bit of a "special need" in that my favorite sort of critter is a ferret. And they need at least enough A/C to "take the edge off", they're very heat-sensitive. Which means running AC even when I'm not around and if boondocking, that could get downright annoying...unless I had enough solar going on to allow at least one 9000btu unit. In that case I'd set up a decent heat-barrier in mid-hall that is also a weasel barrier <g> and cool a smaller area. As to oil supplies...I dunno yet. Still studying the matter. I do know that gasoline has crossed the $3/gal level here in California and diesel isn't far behind. I tossed out the Chinese hydro thing as an example, a better one is that new offshore oil rigs are being built in places where the supplies (predicted years to exhaustion) are low, something that smacks of desperation. I could go on. Anyways. I dunno, I'm going to do more digging into both sides of that issue before spending anything...gotta score the basic bus first . (Bloody cash really should be in-pocket soon...it's like two weeks late now, we're at the point where we're complaining to the judge...) | ||
| James Maxwell (Jmaxwell)
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Jim: I use a Trace C-35 controller. Prev. I used a Kyocera controller with no better results (It shorted out, thus the Trace). I have 4 matching 125watt panels, 12v, wired series parallel for 24v output. I consulted w/3 different "solar experts" on this wiring arrangement since I had my "doubts" about it. All assured me that it was the thing to do as long as I used panels that all spec'd within 5% range. Truth is, in my opinion it has never worked anyway near what it should. I believe the rated ampacity is 14.4 and I have never seen more than 8. Wiring is all over-sized, all connections are sound and secure, wire runs are less than prescribed. Yet, the one that "examined" it for me after I had it all up and running, could find nothing wrong or make any recommendations to peak the efficiency. His final conclusion after conducting the factory prescribed tests on each panel and the controller; "Oh well, shit happens, and some things just can't be explained." Therefore, IMHO, solar is great power source for Tibetan Monks and hermits. When the entire system is considered (panels, controller, battery bank, inverter) I probably have in excess of $6k involved. Fact is, it won't keep up with my 30" LCD wide screen tv/monitor, and that's not even considering anything else. Fortunately, I have redundancy w/the genset that also utilizes the batteries and the inverter/charger. My other conclusion is that anyone would be hard-pressed to find a more expensive source of electricity. If solar, or sources similar in nature and functionality, are the future, the picture is bleak. | ||
| Jim (Jim_in_california)
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>>If solar, or sources similar in nature and functionality, are the future, the picture is bleak.<< Agreed, unless we get some serious breakthrough. That aside, your Trace solar controller ain't the best possible choice. It doesn't have MPPT. You'd probably get somewhere around 20% more power that way and maybe as high as 30%. http://www.blueskyenergyinc.com/pdf/Blue%20Sky_What%20is%20MPPT.pdf http://www.thesolar.biz/RV%20Power%20Products.htm | ||
| FAST FRED Rating: N/A |
If cost is a factor a fine 2000 W Freedom Marine 20 has the ability to put out 4500 W for 5 seconds and only costs $1,100. NO its NOT sine wave , so will be sorta weak if used with a heavy induction load (air Cond) , but for most uses should be just fine. DC air cond makes sense , till you figure the cost of a 100A battery charger to be able to operate at the Power Pole. Comes up almost as cheap to get an inverter , and 120V carbunkles are ANYWHERE , should the unit die some hot day. FAST FRED | ||
| Jim (Jim_in_california)
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If you've got a big enough 12v (or 24v) battery bank you'd want a 100A battery charger regardless. And they're not that expensive...55A Iotas are about $150 and the duplex smartcharge adapter is $35...you end up with a 110A smartcharger that can "scale back" to just one if the other pukes and dies. | ||
| James Maxwell (Jmaxwell)
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FF: Agreed. I just bought a Freedom 20, factory authorized service center rebuilt, 1 yr. warranty, RC7 remote---$601.50 delivered---on that unmentionable auction place. It's for a friends motorhome. I shopped new, best I found was $1185 + shipping w/the remote. Jim: I've heard that "it's not the best, let me show you this little jewel for only $$$." too damn many times. You couldn't imagine how many times so far, and here I am $6k later. I've seen what is purportedly better, and quite frankly, they appeared to be a little bit "smoke and mirrors" and that opinion is re-inforced when I back them to the wall on the extent of guarantee that's it's the little jewel they claim. Are u willing to guarantee that u will completely re-imburse the cost to me, which includes my time to get it, install it, remove it when it turns out to not be the "jewel" re-install my old one, and return the "jewel" That always seems to get met with some sort of "dumb look". | ||
| Jim (Jim_in_california)
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James, all I can say is that there's a LOT of data on solar stuff out there that doesn't come from people who sell stuff. And on those sites, MPPT tech is taken very seriously, it isn't "smoke and mirrors". The idea of altering the input voltage on the solar array does seem to matter. You aren't doing it at present. The only "dumb look" you'll get from me involves asking me to guarantee somebody else's gear and your installation. That is indeed dumb. | ||
| Tom Caffrey (Pvcces)
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Jim (Jim_in_california), the numbers that I've seen so far say to figure on a 10% overall gain in output. Any more than that is gravy. As I understand it, there are a few exceptional circumstances where the percentage could go quite a bit higher, say in winter sun or if there is a big voltage mismatch between the batteries and the solar panels. In the more common situations, if the panels are chosen properly, there is no reason to expect large gains with the MPPT. With what those cost, it can be real hard to make that controller pay off. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher | ||
| Jim (Jim_in_california)
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Tom, the "Solar Boost 2000E" is an RV-sized (20 amps max) MPPT solar controller that goes for less than $200 at the link I gave above. I don't consider that very extreme to get MPPT tech...it's only about $50-$75 or so at the most over the cost of a non-MPPT controller. Even if it does only give you a 10% boost...if your solar panel investment is high enough (and I'd say four 125 panels qualifies) you'll get your money's worth. If we were talking about a $500 Outback MPPT controller I'd be inclined to agree. | ||
| Sharon Mead
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This is from a woman's point of view. All this talk about solar power, I don't really understand half of it, but, one thing I do know. I LOVE our solar power that we have had the last 11 years. We now have a total of 620 watts of power, a 2500 watt Trace Inverter and six 6-volt golf cart batteries. We have more than enough power to run our computer, satellite, printer, microwave, automatic coffee pot, etc. I don't think we have ever used even half of our power output, ever. Also, have you ever considered running 12 volt swamp coolers in place of air conditioners? That's what we have on top of the bus we are converting. Of course, it would only work in the dry climates out here in the west, but, it's just a thought...thanks for listening... | ||
| Jim (Jim_in_california)
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Thanks Sharon. Roughly where in the country are you? Don't need your address or even your state, I'm just trying to get a feel for what sort of climate you're dealing with? | ||
| Mike (Busone)
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I have thought about a swamp cooler but I was concerened about the water sloshing out when underway. Did you use a roof or wall mount model? | ||
| Tom Caffrey (Pvcces)
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Jim, I don't think the 2000E is an MPPT, from what I see on the web page. It looks like a PWM. If you double what you're talking about, you can get into the 3048. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher | ||
| Jim (Jim_in_california)
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Tom, no, the 2000E does indeed have MPPT. The only "drawback" is the peak amps output at 25 which is still plenty for most RV/bus installations. That dealer's site starts at the very top saying everything on that page had MPPT. I didn't think they were wrong as they have a decent rep for competence. I double-checked at the manufacturer's site: http://www.blueskyenergyinc.com/controllers.htm --------------- Solar Boost™ 2000E Data Sheet (updated 3/2/05) Known as the best 25 amp current boosting solar charge controller available. An upgrade of our popular 20 amp Solar Boost 2000, it will support up to 25 amps and includes an equalization function. The technology is "Maximum Power Point Tracking" (MPPT). --------------- ...and their data sheet for the 2000E: http://www.blueskyenergyinc.com/pdf/SB2000Edatasheet.pdf Apparantly there was a plain ol' "2000" model without MPPT. I've seen other lower-power-level MPPT controllers, in some cases for a bit less money - but none that could take a battery temp sensor. I *think* the 2000E is the cheapest MPPT/battery temp type solar charger you can get, or at least that I've seen so far, or at least it's a very good deal. OH, one other key limitation: the 2000E only supports 12v battery banks, not 24 or 48. So that's another limiting factor for some, people with higher-voltage battery setups will need to jump to another model and another $150 or so. | ||
| James Maxwell (Jmaxwell)
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Jim: BlueSky was formerly named something else, but I have been aware of their product line for some yrs. now. A company named MorningStar use to make the same claims and maybe still do. My opinion stands: MPPT technology claims are largely "smoke and mirrors". You will notice that they rely on a very broad range of expected improvements, with no guarantee of anything-0-NADA-Zilch! My admittedly limited knowledge of electrical principles is that Voltage and Amperage are 2 very distinct characteristics and I fail to see anywhere in their explanations of the their technology how they convert lost voltage into gained amperage. In my pursuit of solar panels, I quickly learned from several sources that the crystalline structure, composition, and arrangement, coupled with several different configurations of those crystalline cells, determined PAV and PAI. As I recall, mine are 17.7v peak and 7.2a peak. So, at high demand (discharged batteries) I am not losing that much of the voltage at bulk rate charging, considered as a % of the available. Once the batteries begin to approach a full state, the controller tapers downward to absorb, which does not require a higher amperage input. Perhaps more than what I'm getting but certainly far less than Max or Peak. Nevertheless, I have thus far failed to see a technical comprehensive explanation of exactly how MPPT transforms voltage to amperage. The Kyocera dealer that inspected and tested the panels and wiring (and the Trace C-35) could find nothing wrong with his panels (determined from individual panel testing) or the Trace (Although he too shared your opinion of it). His only recommendation was to sell me an upgraded Kyocera controller (I don't recall what brand name they market them by); one very similar to the one that shorted out on me, only the new one had 24v system capacity, which the original did not. It did not have 48v capacity, as the C-35 does. | ||
| Tom Caffrey (Pvcces)
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James, there are certainly many devices capable of converting voltage to amperage or, for that matter, amperage to voltage. It sounds to me as though that function in your controller isn't working, if you tested it in full sunlight. There's really not much mystery anymore in devices that swap voltage and current; the tricky part to me how the controller makes the determinations that govern the conversions. In any case, I would expect that you should get something like 90% of the power out of the controller that you put into it. If you feed it with 100 watts of 20 volt power or 5 amps, you should get around 90 watts of 13 volt power or around 7 amps out of it. Maybe the losses in the controller are eating up a good part of the power boost that they are supposed to give you. If that is the case, you can tell by a careful measurement of panel power and controller output. If you get even 101% over what the bare panels would give you, then it might just be working! If that's the case, it probably won't be worth $4-500 of my money. Tom Caffrey PD4106-2576 Suncatcher | ||
| Tom Caffrey (Pvcces)
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Jim in california, I'll check that model again. Thanks for the info. Tom Caffrey PD4106-2576 Suncatcher | ||
| Jim (Jim_in_california)
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James: Blue Sky used to be called "RV Power Products" and specialized in mobile solar gear. When they wanted to expand into sales of fixed-installation off-grid hardware they did a name change to reflect a more general product line versus the "mobile niche" and make no secret at all of their former name. Under those circumstances the name change doesn't bother me. I did a whole pile of research on MPPT for a post to this thread, looking for examples of independent analysis NOT done by dealers or vendors. And naturally, my PC crashed right as I was finishing up  . Sigh. Look, go google: MPPT review ...and there's a pile of hits. The upshot is this though: it DOES work, but performs best (over a convensional controller like the Traces or Morningstars) either when it's "cold and sunny" or the battery bank is fairly flat. One example review from Home Power Magazine (2000) is archived on the Blue Sky site, reviewing Blue Sky's first MPPT product: http://www.blueskyenergyinc.com/pdf/SB50ttw.pdf Other reviews archived at the Blue Sky site: http://www.blueskyenergyinc.com/reviews.htm There is also a prominent critique of the Home Power MPPT review: http://www.ka9q.net/pv/hprv.html http://www.ka9q.net/pv/pptnotes.html This is good material but was written in 2000. Since then, the cost of solar panels has stayed flat or even increased a bit while the cost of MPPT controllers has dropped significantly, esp. when we're talking "RV grade" (the 2000E is less than half the cost of any MPPT controller available five years ago). Therefore his basic thesis that the same money should be put into another panel versus an MPPT controller no longer holds up. We should also note that in RV/bus/boat installations we have limited "real estate" for panels and hence it may be worth trying to squeeze every drop out of the panels we can fit in. Esp. when the up-charge for MPPT is only in the $50 - $75 dollar range. The critique dates to when the cost difference was $400 or more... | ||
| Tom Caffrey (Pvcces)
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Jim, thanks for doing that research. When we get around to looking for solar panels, I expect to put your effort to work. Tom Caffrey PD4106-2576 Suncatcher | ||
| Jim (Jim_in_california)
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Heh. Well we haven't even started talking about the panels. Unisolar seems to make panels that are "tougher" than normal - some sources describe them as "unbreakable" which I rather doubt but they do seem to be a tougher design. If you expect to encounter tree branches on funky sideroads they might be something to think about. Problem: most places only sell the 64watt variant which in my opinion is too small. There's a 116w version that's harder to find. This page has the lowest price on the 116 that froogle knows about: http://www.infinigi.com/unisolar-us116-116-watt-solar-module-24v-p-42.html?ref=100 $500 a pop, which isn't TOO bad a price for the wattage. (Note: that page has an error, the first paragraph on "flexible panels" only refers to 32w and below Unisolar specialty panels, read below that for the description on the framed types like the 64/116). But many sources talk about how tough these are compared to anything else, they're a premium panel. The other drawback with the Unisolars is that they're physically larger (more surface area) for the same wattage compared to the BP/Shell/Sharp types, in addition to less power for the buck. Best prices I've seen on BP panels: http://www.thesolar.biz/BP_solar_panel_pricing.htm (Hmmm...$500 for 116 ain't THAT bad...) I've been kinda pondering something. It might be possible to take a big sheet of plywood the width of the bus and just taller than the bumper-to-roof height. This would be mounted on a hinge at the roof and packed with as many high-density panels as possible. In transit it would be lowered and the bottom edge would mate with the rear bumper. When parked you'd raise it to horizontal with a prop-rod or maybe even tilt it for max sunlight. The idea is that while rolling the panels would be protected from tree branches, rocks and the like...they're screwed only if somebody rear-ends you really hard and then you've got other worries (and uninsured motorist coverage I hope!). On rear-engine buses that have some "heat vents" at the rear this might be either impossible or the size would have to be limited but on a Wanderlodge/Bluebird or other "puller" it might work real well. It would also be easy to clean the panels without going rooftop. In looking for prices, I came across this page with downloadable data sheets for each panel (and other key bits) - these will tell you relative panel sizes, voltages, etc: http://www.southwestpv.com/DOWNLOAD.HTM Another good data sheet download page: http://www.windsun.com/ Another good "panels pricing page": http://store.solar-electric.com/hiposopa.html Smaller panels, but there's an interesting deal on multi-pack 64w setups (OK if you're building your own mounts and you'd have less drop if one died): http://store.solar-electric.com/40to89wasopa.html (Those last two pages are neat because they identify the 12v and 24v modules...) Hmmm. The more I look, unless I see data going the other way the more I like the Unisolar 116s if I'm going to do rooftop mount. But they can't be direct-wired to a 12v battery unfortunately... Ohhhh yeah. That reminds me. If your panel voltage doesn't match your battery bank, you MUST use a fairly advanced charge controller that's now almost certain to have MPPT as well (Blue Sky, Outback, etc.). But if you pick panels that are either the same voltage as your battery bank or can be wired that way (fr'instance, 12v nominal panels can be wired series/parallel for 24v) then if your charge controller breaks in the field, you can (on an emergency basis) wire the panels straight to the battery bank. BUT you'd better have a battery charge meter around and watch it like a HAWK...this is NOT OPTIMAL but it's doable if you're out of other options...so that sort of combination is a better bet for the hardcore dry-camper - or somebody whose income fluctuates and might need to function for a while on very limited cash when the solar controller blows up... | ||
| James Maxwell (Jmaxwell)
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Jim: Do some more research on the crystalline structure and configurations of various panels. You will find that the Unisolars are "thin film" which happens to be the least efficient of the bunch. That is the explanation for their lower power output/ square area ratio. Most efficient are the single crystal cell structures like Siemens and BP. However, they have a higher % "shading" drop-off than multi-crystalline structure. Thin film has the 1 advantage of less "shading" drop off expressed as a % of peak potential. As you point out, real estate area gets critical in the RV application, which makes efficiency/size ratios a prime consideration. But, as you probably have already surmized, I ain't anything near an expert in this field. Closest one I've encountered was the US West Coast Field Rep for Kyocera and I had one hell of time w/his English and accent. There is a "sharp" salesman that works for the big internet seller located in Temecula but I can't remember his name. He was the first one to suggest to me that MPPT was more BS than substance by his field testing. | ||
| Jim (Jim_in_california)
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James: no argument re: the inefficiency-per-square-foot or whatever of the Unisolars. When I finally score a dang bus (VERY soon, swear to God <grin>) I'm going to take measurements up top, see how much "real estate" I've got to work with. IF I can get four or five Unisolar 116s at a good price and IF the "real estate issue" isn't a problem (depends a lot on the bus, a 34' Bluebird-based rig is the most likely candidate) then the toughness of the Unisolar may have it win out despite their other drawbacks. I'm also wondering which other panels might be "intermediate" in toughness between, say, the BPs and the Unisolars. Or if all else fails, I'm pondering a hinged sheet of plexiglas for in-travel use protecting the panels...or in case of hailstorm or something... | ||
| Vin (Billybonz)
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Jim, I saw a slick setup with hinged panels. There were 4 attached to the roof and 4 hinged. When folded up, the panels faced each other and were protected. When flipped out they provided a small bit of shade to the RV windows. Only down side is the panels were not working when folded up but the engine would provide charging then anyway. Just a thought. Bones | ||
| James Maxwell (Jmaxwell)
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Jim: Breakage is very rare on a bus. I have heard of 1 incident from hail, 1 from a lobbed rock that hit it, 1 from a baseball that came down on it, and 2 or 3 that people stumbled on the roof and either fell or stepped on them.(I have stepped on mine on the edges near the frame many times since mine extend into the roof radius.) Mine have been hit several times by falling pine cones with no problems. | ||
| Jim (Jim_in_california)
Rating: N/A |
>> Only down side is the panels were not working when folded up but the engine would provide charging then anyway. << Yeah, that's exactly what I was thinking. The "double stack" you describe is WAY slick but would be on the tall side...lotta wind resistence. ---------- You know, Unisolar has these oddball "peel and stick" thin film setups. See also: http://www.atlantasolar.com/product_info.php/products_id/956 18' long(!) by 16" wide, comes in a roll. You're *supposed* to stick 'em to galvanized special pans: http://www.atlantasolar.com/index.php/cPath/26_30_31 They say they're rated for 160mph winds. Well instead of using "pans", why not "peel and stick" the suckers straight to the roof of a bus! It's not as crazy as it sounds. 18 feet long will fit between two rooftop ACs for many of us. 16" wide translates to 5.5' total width if you lay down four as strips, plenty to allow at least a 1.5ft "walkway" down the middle so you can do roof maintenance without walking on the panels (which are probably tough enough to take a little bit regardless). These "thin film" panels work better the hotter they are (unlike other types) so using the roof heat helps. Your wind resistance would go WAY down. At the leading edge, I'd screw in (to the bus) sheet steel or aluminum strips across the forward edges of each panel so that "wind peel" can't start. For the same reason I'd run the wiring along the back edges (aimed towards the back bumper). This would be THE most aerodynamic bus-mounted solar "panel" setup possible! And other than the "forward edge protection strips" you're punching far fewer holes in the roof of the bus compared to corner brackets for each hard-panel in a traditional setup... If 18' is too crazy for your roof layout, they come in shorter smaller-wattage form factors with respectable watts-for-the-buck ratios: http://www.atlantasolar.com/index.php/cPath/26_30_140?osCsid=dd3ee2e47f06d417ff3c5478a2215 ebe | ||
| Jim (Jim_in_california)
Rating: N/A |
OH GOD those DC-Airco 9000s are FIVE THOUSAND BUCKS!!! Eeek! Screw that idea! |