If you have Solar, how many Watts do you have and what is the length of your bus? Also is your bus all electric or do you have Propane on board?
Sunlight or shade. Summer or winter. Color of your Bus Conversion? Dunno. Dynamic.
I have three panels of 100 watts each, they do a great job under "normal" conditions, but it all depends on usage and everyone uses power differently I will run my generator for one hour each morning under boondocking conditions to replace what was removed during the night (furnace, refer, TV and other trace users.. After that hour, and in sunlight, the solar will hold its own all day.>>>Dan (could use one more panel)
What Dan said. Anything less than 400W is largely a joke unless you drastically modify your lifestyle from what most people consider "normal". And you're still going to need a generator for the heavy lifting.
The only reason I have eight big grid-tie panels is because ten or twelve won't fit! I decided I could either laboriously calculate all my electrical loads and then arrive at a notional size of my PV system, or I could instead just carpet the whole darn roof with panels. I know what's easier. It's like when folk ask me why I have 220 gallons of water capacity - the simple answer is because I don't have space for any more! I work on the basis that RVers don't usually complain they have too much of anything. If in doubt, err on the side of excess!
Seriously though (?!), if the sun don't shine I want to have three days of power before my batteries reach 50% SoC. In practice I would probably use my emergencies-only generator before that point. I also want enough PV to be able to charge the batteries at the upper end of their recommended 5-13% charge rate, so if the sun is low or weak I can still get a useful charge into them. I think that for most of the year I will have excess power from the panels, but I can heat water with it or use it to run power tools so it won't go to waste.
I've designed my bus to comfortably support one person for at least a month off-grid, or two people for at least a fortnight. That includes taking a nice shower every night, cooking, using the loo, etc etc, in other words not deliberately scrimping and saving. The only anticipated limitations to extended boondocking will be of fresh water and food, not electricity!
John
Just got the Barn at the ranch 80 new PV panels replacing 75 old ones that slowly went bad also new inverters. Two of the inverters were still usable and 3 panels which were newer are usable.
Don't Know not much about these numbers can I in any way use this on the bus. (It was use on a regular house system where it made electric both ways, to the house and back to the power company). With a Magnum 4024 Hybrid sharing inverter/Smart 120 watt charger which I use now with 4, 6volt deep cyle batteries 232 AH wired in series 24VDC, with a 7KW genny and 50 amp shore with a Auto transfer switch. also have a 20-60 Vanner that handles 12 volt system and 24 V start batteries Group 31's(2).
Each Panel 190 Watts each Total=570 Watts
Voltage 37.8
Current 5.06
open circuit 45.3 Volts
Short circuit 5.56A
Tolerance +5
Inverter is a Sunny-boy 2500
Or should I just use them on my Ranch Trailer?
I have two 100 watt panels feeding two group 31 batteries. Works well for boondocking and really minimizes generator use depending on how much sun you can get. Would like to add a few more panels to eliminate generator use, but flat panels on a curved roof limits that.
Matt
Solar is near the top of the discretionary list. Monitoring and calculating the range of typical energy usage during 24 hours. Based on that the house battery pack can be sized and the amount of solar generation estimated. Broad guess is a couple 280-320 watt panels (500 watts usable) should keep the house batteries charged up. We us very little during the day and most consumption is lighting, some short microwave usage, refrig (x24), and hot water. just hoping to eliminate running the generator on most days.
Generator is expected to run the AC when used. not planning on sizing system to run AC off batteries or plan on running multiple days off batteries. If it don't shine and batteries need a charge, that's why the generator is there.
I have 1580 watts and the only reason I don't have more is because at the time it's all I could get to fit on the roof. With 1600 amps of AGM's.
I believe what John says is true, you can never have enough charging power. There are lots of partly cloudy days.
Jerry
Quote from: Dave5Cs on December 29, 2017, 07:42:36 PM
Just got the Barn at the ranch 80 new PV panels replacing 75 old ones that slowly went bad also new inverters. Two of the inverters were still usable and 3 panels which were newer are usable.
Did the solar panels themselves go bad? From what I have read it is extremely rare to have the panels themselves go bad. There are panels still running from the 1970s when solar was just getting started. It seems sort of silly that today's panels have a 25 year performance warranty, but many only have a 12 year warranty against other failures? Isn't the panel performing at zero percent of original performance if it fails entirely?
I would like to put four 60 cell panels totaling around 1,000 watts on my bus, but they have to be cheap around $100 per panel to make it worth the effort. The $750 total cost of the system could buy a lot of diesel for my generator. I don't use the bus enough to make solar really pay off. The additional four to six hours a day of not hearing the generator run might be worth it although my generator is pretty quiet.
Quote from: belfert on December 30, 2017, 04:56:00 PM
I would like to put four 60 cell panels totaling around 1,000 watts on my bus, but they have to be cheap around $100 per panel to make it worth the effort. The $750 total cost of the system could buy a lot of diesel for my generator. I don't use the bus enough to make solar really pay off. The additional four to six hours a day of not hearing the generator run might be worth it although my generator is pretty quiet.
Unless you get a great deal on used panels, you probably won't find PV for that price! I paid $0.79 a watt a few years ago for my new Grade B made-in-USA Sharps (they are cosmetic blems with some cells not exactly the same color as others!), and prices have dropped further since then, but you have to buy pallet-loads to get down to $0.50 a watt. For me, not having to hear a generator was a primary reason to go solar - if I'm parked somewhere beautiful I really don't want to hear one droning away for hours, and because I'll be in the desert Southwest most of the time the choice for me was obvious.
John
Typical current pricing in the Bay Area. not 50 cents but still very attractive pricing. One consideration of mine is not having panels so wide they hang much beyond the curve of the roof. Best configuration is hidden or barely visible panels.
https://sfbay.craigslist.org/sby/for/d/new-320w-solar-panels-only/6412950964.html
https://sfbay.craigslist.org/sby/for/d/285w-mono-solar-panels-with/6428304967.html
https://sfbay.craigslist.org/nby/ele/d/renesola-250w-pv-solar-panels/6431199743.html
Quote from: Iceni John on December 30, 2017, 05:12:07 PM
Unless you get a great deal on used panels, you probably won't find PV for that price! I paid $0.79 a watt a few years ago for my new Grade B made-in-USA Sharps (they are cosmetic blems with some cells not exactly the same color as others!), and prices have dropped further since then, but you have to buy pallet-loads to get down to $0.50 a watt. For me, not having to hear a generator
I paid 27 cents a watt for twenty 300 watt used panels last March. I paid 45 cents per watt for twelve 265 watt new panels in October. Prices for solar panels have gone up quite a bit since March. I believe back in March I could have found some new 60 cell panels for close to $100 each. I watch CL for panels locally and the prices some people want is ridiculous. One guy wanted $10,000 for an old 900 watt array with inverter.
In the southwest USA I regularly see panels on CL for $100 or just over that for new panels. Unfortunately, I don't live down there, but I will probably be driving through in May.
Brian,
I agree that prices on panels, particularly those from China have crept up. It seemed a response to the govt. and the trade imbalance with China. Not following but solar credit programs may be changing as well. Either way, for the few panels that'll fit on a bus, it hardly matters. For us in Calif. the asinine 30 cent tax on diesel dents me much more.
Quote from: windtrader on December 31, 2017, 11:12:00 AMBrian,
I agree that prices on panels, particularly those from China have crept up. It seemed a response to the govt. and the trade imbalance with China. Not following but solar credit programs may be changing as well. Either way, for the few panels that'll fit on a bus, it hardly matters. For us in Calif. the asinine 30 cent tax on diesel dents me much more.
And, just as they planned, China "dumped" enough solar panels to put many of the larger US manufacturers out of business (and drive the European manufacturers out of the market). Now that there is little competition, they're putting their prices up again.
Gary, if you are serious about trying solar, you could start with one or two of proper size that will work with future expansion in mind. Install with that in mind so you don't have to remove and relocate existing ones to make room for more. Do the wiring with that in mind also. This is where the recommendations of current users will be beneficial as far as routing the wiring and controller locations. I'm curious also about such things, also mounting, wind resistance, access to other items on roof, and also visual appeal or ugly monstrosity. This way you can get your feet wet. I suppose you could buy some from Harbor Freight to try, although some consider them junk, but I don't know if from actual use of that item or just a general bias against HF. Just some thoughts
BTW, does it hurt to have panels installed and in sun without being connected to anything? Sort of like when getting them first installed.
Also, do they usually have places on them for mounting or is this a personal need to fabricate issue.
Do you wire them like Xmas lights, or run all leads independently to controller.
Do these get wired to inverter in a specific location or how do you connect them to inverter/ generator/ house battery system. Just interested in general idea for now
I considered the HF route but that is a throwaway and really not such a deal.
Victron MOPPT charge controllers are top notch, starting at 100 bucks for 75v/15amp.
https://www.amazon.com/Victron-BlueSolar-MPPT-Charge-Controller/dp/B00U3MK0CI (https://www.amazon.com/Victron-BlueSolar-MPPT-Charge-Controller/dp/B00U3MK0CI)
Just add a good 280/320 watt panel or two and you are off to the races with a solid foundation you can build on, no throwaway.
Get up on the roof and measure how wide a panel you can place without it being a visual eyesore from on the ground site lines. Some may not find this a concern but my bus is not going to have a bunch of panels hanging out. There should be plenty of room to place a few panels with relative ease.
Quote from: chessie4905 on December 31, 2017, 11:48:24 AM
Gary, if you are serious about trying solar, you could start with one or two of proper size that will work with future expansion in mind. Install with that in mind so you don't have to remove and relocate existing ones to make room for more. Do the wiring with that in mind also. This is where the recommendations of current users will be beneficial as far as routing the wiring and controller locations. I'm curious also about such things, also mounting, wind resistance, access to other items on roof, and also visual appeal or ugly monstrosity. This way you can get your feet wet. I suppose you could buy some from Harbor Freight to try, although some consider them junk, but I don't know if from actual use of that item or just a general bias against HF. Just some thoughts
BTW, does it hurt to have panels installed and in sun without being connected to anything? Sort of like when getting them first installed.
Also, do they usually have places on them for mounting or is this a personal need to fabricate issue.
Do you wire them like Xmas lights, or run all leads independently to controller.
Do these get wired to inverter in a specific location or how do you connect them to inverter/ generator/ house battery system. Just interested in general idea for now
1. Don't waste you money and time with HF's solar panels. They don't last. Buy 'real' panels from reputable suppliers. And don't buy flexible panels either.
2. Panels don't care whether you're using the power they make, or not. They won't last longer or shorter whether they're connected or not.
3. PV panels are just a series of individual cells attached to a substrate with a glass front over them, and the entire shebang is mounted within an aluminum frame for protection. Some folk directly mount the panels to the bus roof, but you have to careful you don't stress or bend them that way or they will crack. I've mounted each of my panels inside a separate support frame made from 1.75" 6063 angle, with a half inch space all round in case I need to replace a panel in the future with one that is up to 1" larger. These support frames are hinged to a walkway between my two roof hatches, and supported on their outside edges by stainless struts that can lift them up to 45 degrees above horizontal for winter insolation. When down against the roof for travel they are at 21 degrees below horizontal due to Crown's curved roof.
4. Panels can be wired in series or parallel. Each panel has an output cable with MC4 connectors, and should be connected to a combiner box that then sends power to the charge controller. I have my panels in parallel to minimize losses if one panel is shaded, and so the charge controllers are down-converting voltage (and boosting current) by a factor of only 2 - if MPPT controllers have to buck greater voltage differences their efficiencies drop significantly and they get hotter.
5. Charge controllers and inverters should be mounted as close to the batteries as possible, but not in the same compartment as them. Cables should be as short and fat as possible, with correctly-crimped terminals (no hammer crimpers!), and copper busbars can be used wherever possible.
HandyBob has some good thoughts on RV solar systems: https://handybobsolar.wordpress.com/ (https://handybobsolar.wordpress.com/)
The gurus and experts at the Northern Arizona Wind & Sun forum always have sensible words of wisdom: http://forum.solar-electric.com/ (http://forum.solar-electric.com/)
John
So they don't need connections to inverter and inverter isn't effected by their output directly to batteries through their controller? Do they or controller cause a drain to batteries if they aren't charging? For example, if coach is sitting inside garage for, say as month.
Thanks for the info so far. I'll check out those sites.
Quote from: chessie4905 on December 31, 2017, 05:42:05 PM
So they don't need connections to inverter and inverter isn't effected by their output directly to batteries through their controller? Do they or controller cause a drain to batteries if they aren't charging? For example, if coach is sitting inside garage for, say as month.
Thanks for the info so far. I'll check out those sites.
Solar is just one of several ways to charge batteries, so the inverter is connected to the batteries in the usual way. Remember, solar is providing power, and the inverter is drawing power. As the SmartGauge folk state, the inverter and loads are connected to the same location on the batteries as the charger and solar charge controller. And if the sun isn't shining and the charge controller isn't sending power to the batteries, there won't be any drain from the batteries - the CC's output is protected by diodes (as are the solar panels themselves). However, if the bus is unused for a long time, it's prudent to completely turn off the batteries to avoid phantom loads from slowly draining them, but it's still a good idea to have a small trickle charger on them to always keep them at 100%.
I have a Blue Sea 6006 switch for each battery bank's output
(I have two separate house battery banks in parallel) to the inverter and DC load center, but the charge controllers are always connected to the batteries even when those load switches are Off. I can turn off the PV inputs to the CCs, and the outputs from the CCs to the batteries, by separate Carling Type C circuit breakers. The CCs and inverter/charger are in the underfloor storage bay, but only a few feet from the batteries themselves that are in their own separate vented compartment; power is taken through the wall by VTE Power Posts and Power Bushings. All cables between the batteries and the main DC positive busbar are 2/0, and from the busbar to the inverter is 4/0, with tinned copper lugs circumferentially crimped with a FTZ 94284 crimper tool.
John
John,
QuoteHowever, if the bus is unused for a long time, it's prudent to completely turn off the batteries to avoid phantom loads from slowly draining them, but it's still a good idea to have a small trickle charger on them to always keep them at 100%.
Is there some issues with using the PV/CC to stay connected to the house bank and keep them topped off? What other options if the bus has no access to AC while stored?
As had been said, buy as many as you can afford. And as many as you can fit on the roof. I believe solar panels will only go up in price in the future. I can only fit about 1000 watts, wish I could do 3000.
Quote from: windtrader on December 31, 2017, 08:23:18 PM
John, Is there some issues with using the PV/CC to stay connected to the house bank and keep them topped off? What other options if the bus has no access to AC while stored?
My CCs are always connected to the house batteries even if the batteries' load switches are Off. I have to turn off the CCs' own circuit breakers to stop the batteries from being charged.
John
I have upgraded from 45 watts (PO) to 500 watts had to change/upgrade, charger and wiring. We will be in Quartzsite this month to see how it works. I do have LP on board.
Quote from: belfert on December 30, 2017, 04:56:00 PM
Did the solar panels themselves go bad? From what I have read it is extremely rare to have the panels themselves go bad. There are panels still running from the 1970s when solar was just getting started. It seems sort of silly that today's panels have a 25 year performance warranty, but many only have a 12 year warranty against other failures? Isn't the panel performing at zero percent of original performance if it fails entirely?
I would like to put four 60 cell panels totaling around 1,000 watts on my bus, but they have to be cheap around $100 per panel to make it worth the effort. The $750 total cost of the system could buy a lot of diesel for my generator. I don't use the bus enough to make solar really pay off. The additional four to six hours a day of not hearing the generator run might be worth it although my generator is pretty quiet.
Brian E. Yes the Panels 75% were going bad over time Slowly but surely. They came out twice and told us it was the inverters and that they needed to be replaced which they did for 2500.00 per unit. Turns out we called another company and had them check it all out and it turns out the panels were going brown at the edges and when they tested 50% of the panels were having trouble keeping up. Look at the edges from the frame in and see if they are brown and keep an eye on it and test some to see what they are putting out compared to what they are suppose to. We got new panels and inverters. This system we can monitor on our smart phones or computers and see what they are doing at any time. Part of the cost was covered by the state Solar fund.
Someone in Quartzsite told me yesterday, you should have 1.5x the amount of amps of solar panels than you have in your batteries. Never thought of relating battery storage to the size of the solar panels, but this makes sense, irrespective of what you have for power needs in your coach. It is all about how many amps you have total in your batteries. I would like to hear other opinions on this.
Quote from: Gary Hatt - Publisher BCM on January 28, 2018, 07:47:53 AM
Someone in Quartzsite told me yesterday, you should have 1.5x the amount of amps of solar panels than you have in your batteries. Never thought of relating battery storage to the size of the solar panels, but this makes sense, irrespective of what you have for power needs in your coach. It is all about how many amps you have total in your batteries. I would like to hear other opinions on this.
Did you mean that the watts of solar should equal 1.5x the amp hour capacity of your battery bank? That would make more sense. Actually, i would say that would be the upper limit so as not to charge above the batteries maximum charging rate capacity on good sunny days or you will drastically reduce thier lifespan. Again, as has been stated before, how much solar you need really depends upon your average power usage, not so much the size of the battery bank. If you have a battery monitor that tracks amp hour usage this would be a great place to start. Monitor your usage over the course of a week and do some math.
Sent from my SM-G930T using Tapatalk
Quote from: Gary Hatt - Publisher BCM on January 28, 2018, 07:47:53 AM
Someone in Quartzsite told me yesterday, you should have 1.5x the amount of amps of solar panels than you have in your batteries.
As stated that doesn't make sense. Maybe I could see some equivalency between watts of solar and AH of battery but amps are a current measure, not a power measure. If you had 1000 AH of batteries for easy figuring then 1500 amps of solar even at 12 volts nominal would be 18,000 watts of solar which is not going to fit on your roof. I could however understand 1000 AH of batteries and 1500 watts of solar.
I don't think you should get too hung up on a rule but rather should think about balance and power use. Don't go overboard on batteries while neglecting how you are going to charge them and conversely it doesn't make sense to have a bunch of charge capacity if you can't use it or store it.
Gary, never mind the solar panels. Just go to a Tesla charging station, lol. I was reading how people do that, then use the power at home. Tesla might have to start charging money for plugging in...
JC
I went through this calculation when deciding on the house batteries for our 4108. The Trojan dealer told me that they recommend a charging rate of approximately 10% of battery capacity. We're going to have about 780 Ah between our four L16 batteries (set up as a 12v system), and he said that a 70-amp plug-in charger would be the proper size. In setting up solar, ideally we would be able to charge the batteries at about the same rate.
Going with a formula of Amps=Watts/Volts, a 1000-watt solar setup would provide about 83 amps output under optimal conditions. Since there is no way to always have optimal conditions, bigger would be better. Seems like there are a lot of 'kits' available that include six 160-watt panels (960 watts total), which would be about the smallest we'd consider given our battery setup.
Quote from: richard5933 on January 28, 2018, 09:14:06 AM
I went through this calculation when deciding on the house batteries for our 4108. The Trojan dealer told me that they recommend a charging rate of approximately 10% of battery capacity. We're going to have about 780 Ah between our four L16 batteries (set up as a 12v system), and he said that a 70-amp plug-in charger would be the proper size. In setting up solar, ideally we would be able to charge the batteries at about the same rate.
Going with a formula of Amps=Watts/Volts, a 1000-watt solar setup would provide about 83 amps output under optimal conditions. Since there is no way to always have optimal conditions, bigger would be better. Seems like there are a lot of 'kits' available that include six 160-watt panels (960 watts total), which would be about the smallest we'd consider given our battery setup.
The solar gurus on the NAWS forum recommend charging FLA batteries at between 5 and 13% of their 20-hour rate. Anything less than 5% runs the risk of deficit charging that will eventually sulfate the plates, and anything over 13% will overheat the electrolyte and cause too much water loss. If you will be charging at the upper end of the range it's prudent to have battery voltage and temperature sensors so the charge controller can precisely charge without risk of battery damage. My setup will charge at about a 13% rate in theory, but with typical real-world conditions it will probably be less than that. I still want to push as much power into the batteries as quickly and safely as possible - ideally I want my banks fully recharged by noon or early afternoon, then any PV power produced after that time can be used for discretionary loads such as water heating or running big power tools. My intention is that even in winter I will still be able to fully charge batteries most days from solar, and only if it's raining or heavily overcast will I need my emergencies-only generator. Well, that's the plan!
John