Is anybody using any solar panels on their bus for power ,,I'm thinking about 6 175watt panels ,,a good solar controller to help at keeping the house batteries charged ,,8 deka 6v gel cell batteries for 24volt house system,,hoping to run the house frig and roof vents ,other stuff like the Tv and computer ,trying to keep from running the gen all the time ,,,anyone have any suggestions ideas that would help?
thanks pete 36330
I have a friend with an H345 that has been intensively researching this and he ain't no grease monkey like me. He has a PHD so I tend to listen to comments about the things he persues when he does it.
His research has led him to flexible self adhesive panels. The potential is unlimited. Women's purse flaps to charge cell phones, awnings, curtains or the roof of the camper :)
I love those flexible panels, but they are out of my budget right now. Im still waiting for them to come down. Ive also read that solar paint is in the works, so is solar ink. But for right now, here is a calculator I found online that shows the number of panels and batteries you will need depending on what you want to run http://www.freesunpower.com/system_sizing.php (http://www.freesunpower.com/system_sizing.php) if money isnt an object with you but roof space is, there are ways that I think they could be stacked and then folded out (or extended out automatically) to create sort of an awning when parked....
If.
If they were affordable, and if they were flexible enough to match the roof contour, I would do it. But flat panels on brackets up on a round roof Bus, or that cost a fortune, are not an option.
If we wait just a bit they will very quickly become yeserdays tech ;D
I have 480 watts on the roof and they pretty much keep the fridge and numerous other items going at least till the sun goes down Jerry
Quote from: Jerry32 on May 11, 2011, 08:36:48 PM
I have 480 watts on the roof and they pretty much keep the fridge and numerous other items going at least till the sun goes down Jerry
at what cost? i'd prefer solar with sufficient storage as opposed to a noisy genset. what's the payback period on these panels or others versus diesel that i may have to run to keep the hot water hot, freezer frozen, etc?
pay back? Remember too that when parked at home there is no reason you cant run a good extention cord to your house to power stuff as well. Get double duty out of them
Solar panels are more of a lifestyle choice, because there isn't a payback at current prices from what I remember reading other threads on this topic. Also don't solar panels have a limited and relatively short lifespan? If you are having to put news ones on every six to ten years, plus batteries every five to seven, then that gets to be very costly. I would like to have a solar system on mine, I just don't have the extra $ laying around.
Yes, it is costly...... I dont know even with using the cells double duty how long it takes to recoup costs. I think the solar panels last about 25 years now, at least that's what many of the ads for the newer ones here locally are saying. But they want to install them for 3.33 a watt :o That's just crazy! But if you can solder you can buy the cells individually for under 1.00 a watt. Of course then you have to come up with the materials to mount them in a windproof, rain proof, hail proof container and put them on your roof.....
I have 200w x 3 panels on my roof, a BZ MPPT500 charge controller and 8 AGM's on my bus. The day I installed the system was the last day I ever worried about my fridge. The fridge is a 110v Summit in which I installed a dedicated 2000w sine inverter that is turned on and off by the fridge's temperature control. It's about the most seamless, maintainance free setup I've had in many years! It runs constantly and never needs to be plugged into shore. I Love it.
So to answer your question, YES it was worth the time and trouble. Well worth it. I fought with a 3-way fridge for 5 years. Always having to Level the bus. Always having to screw with lighting the pilot. Repairing the stupid thing 1-2 times a year for one little thing or another. Finding warm food when parked in the desert, 'cause the fridge couldn't keep up. What a hassle. Now, all gone... no hassle... I just enjoy it...
Barn Owl I agree. I was interested for storage w/o power or possibly just slightly more and that is what my friend was wanting to do as well. Drive a circulating fan somewhere for discharging summer heet and turning the air over and keep the batts up while stored w/o power.
Quote from: Barn Owl on May 12, 2011, 04:38:45 AMAlso don't solar panels have a limited and relatively short lifespan?
Many solar panels are warranted to produce their rated output for 30 years, and they will likely keep working a lot longer than that. All you have to do is clean them every so often, and you get magical and totally silent electricity constantly flowing in to your home / bus.
Generators are noisy and annoying - particularly to your neighbors. Anything that can be done to avoid hours of generator usage each day is a huge win.
Solar panels alone are not enough though - to get your monies worth out of them you need to really focus on power efficiency. In our trailer we used all LED lights, and measured and optimized every watt of electrical use. But by doing so, our 200 watts of solar panels allowed us to occasionally go for weeks on end without needing to pull the generator out of the truck - even with us two geeks spending much of each day working away on our laptops.
Solar is one of the best upgrades ever, IMHO.
- Chris // www.technomadia.com (http://www.technomadia.com)
Payback period can depend on what value you want to put on peace and quiet. If you prefer to give expensive RV parks a wide berth AND prefer not to annoy the neighbors when you do, work out the payback period by multiplying the number of nights you DON'T spend in an RV park by the coast per night an average RV park costs.
Works best for those on the road full time. Weekend warriors can never justify solar purely on a dollar basis.
Quote from: boogiethecat on May 12, 2011, 04:47:37 AM
I have 200w x 3 panels on my roof, a BZ MPPT500 charge controller and 8 AGM's on my bus.
Im sure we could use your system as an example of payback. Whatever your fridge is using in average KWH's can easily be converted to utility rates. If we assumed the panels are making 70% power for 10 hours a day, .6KW X10 hours = 6 KW per day, about 180 KW per month, sounds about right for an average fridge? At $0.08 per KWH, thats about $15 month, $180 year, $1800 in 10 years. I cant imagine you have anywhere near that into your setup, and you cant include the fridge or inverter, just the panels, batts and controller. If you used the costs of running the generator intermittently to charge the batts, to keep the fridge running 24/7/365, your costs would likely be $0.25 per KWH or more, and your payback could be within months.
Boogiecat
very slick idea dedicating a inverter for the fridge then triggering it off the thermostat eliminating an unnecessary idling unit.
Very slick very well done very obvious why your so happy :)
Hmmm, I'd be suprised if the cost wasn't at least twice that $1800.00. The typical rule of thumb for residential installations using crystilline silicon technology runs about 6.50 - 7.00/watt. Even at 5.00/watt that 600 watts will run 3K. Add in the cost of replacing your batteries periodically and it's even more. There is really no return in the US without government incentives unless you lease your equipment and sell excess production back to the grid. If you like the flexible thin film products better, you'll likely need to plan on covering your entire bus because they are only about 12-15% efficient, about half that of silicon.
I used a cheapo inverter to run my cheapo water flow control valves and turn on the circ pump(12VDC) in the house fresh system, for my freeze protection system. My deep cycle would power that system for a month and the heat came from the hot water heater. Used some propane but I was protected. Most expensive component was the Thermostat switch with the long bulb sensor. I used water control valves out of common washers that ran off of 120AC.
John
Quote from: JWallin on May 12, 2011, 11:29:33 AM
Hmmm, I'd be suprised if the cost wasn't at least twice that $1800.00. The typical rule of thumb for residential installations using crystilline silicon technology runs about 6.50 - 7.00/watt. Even at 5.00/watt that 600 watts will run 3K. Add in the cost of replacing your batteries periodically and it's even more. There is really no return in the US without government incentives unless you lease your equipment and sell excess production back to the grid. If you like the flexible thin film products better, you'll likely need to plan on covering your entire bus because they are only about 12-15% efficient, about half that of silicon.
Now that is INTERESTING. ASll of what he said.
John
I am surprised that someone did not link this to some of the more recent threads on the subject.
There was a lot of discussion in this thread:
http://www.busconversions.com/bbs/index.php?topic=19713.msg (http://www.busconversions.com/bbs/index.php?topic=19713.msg)
There was some pretty good information there. I detailed my system and noted that I did not feel that it was a good investment for our situation. Too much to post again.
Sean is tied up right now with the Red Cross activity, but his has had some good input on the subject. Here is one of many threads:
http://www.busconversions.com/bbs/index.php?topic=17047.0 (http://www.busconversions.com/bbs/index.php?topic=17047.0)
I am always concerned about what I call "amateur calculations". I don't mean that to be derogatory, but the application calculations for this technology is pretty complex.
There are a ton of variables that need to be factored in to get even remotely close to realistic energy calculations. For example, you need to factor in actual sun days, hours of sun exposure, efficiency of absorption of energy, efficiency of energy conversion, etc. By far the biggest factor is how well you aim the panels. On our vehicles, that is a real challenge. If you flat mount the panels, you loose a ton of "efficiency".
If you have some sort of system to point the panels, you still have an issue with parking the vehicle in a position for maximum absorption. At one trade show, I saw a unit that tracked the sun and elevated the panels to maximize the "efficiency". The price was pretty steep, but might be worth it for some folks. I have not seen them at recent shows, so maybe they folded.
This is a very big investment and there is not a single answer. Each person must justify the cost based on their factors.
Jim
PVCCESS or Tom, has installed solar on the roof of his bus. He keeps his bus in the lower 48 but he lives in Alaska. I think his bus stays in storage for 6 months or so. His bats are topped up and ready to go when he puts the key in the door. He couldn't do that without some sort of pole power and that storage is spendy. I see his application as the baseline need for service......keep the bats charged while you are away. Then all this other stuff enters my concern. I can live with my genny running for a few mins every day. Loosing a bat will mean I will have to run my genny a couple times a day. Lots of malfunctions I can work around but long term storage isn't one and bats left discharged will cost ya big time. And, I am poor.
And what about those wind mills?
John
Quote from: rv_safetyman on May 12, 2011, 11:46:50 AM
I am always concerned about what I call "amateur calculations". I don't mean that to be derogatory, but the application calculations for this technology is pretty complex.
Your probably refering to my amature calculations, and even if your not, your right, im sure the calcualtions needed to figure it out are quite complex. However, once someone has a system working, it is not hard at all to look at it and see what its doing, or copy it. If the guy is running his fridge 24/7/365, then its quite easy to conclude the system is delivering X watts to that fridge.
I also believe that if you build in extra capacity, and derate your need, you should make enough power to keep it going no matter which way your aimed. For example, 600 watts worth of panels running a 100 watt load wouldnt matter so much which way they were pointed.
Paul, I was not taking a shot at you. Lots of folks take a quick cut at trying to analyze the subject and don't take all of the factors into consideration. I was just trying to say that the impact of the variables are pretty darn complex.
For example, Gary (boogiethecat) lives in the San Diego area. He has a lot more sun days and a better year around "sun angle" than someone in Oregon or Washington.
He specifically mentions that his refrigerator is a "Summit". I think that manufacturer is pretty efficient compared to an el cheapo unit. We also don't know what size his unit is. Gary does not have kids holding the door open all day.
I think you get the idea of what I am trying to say.
Yes, it would be fairly straight forward to instrument a coach with an integrating watt meter and measure consumption for that coach over a fairly long test period. But that is the problem. Each of us has a vastly different energy demand. Part of that is lifestyle, part is the coach itself, and part is the geographic/climatic condition.
As I mentioned in the other thread, I have followed the Colorado State University solar technology program a bit over the past thirty years, and my mind boggles at the immense amount of technology involved. That is the geek side of the picture. I have wanted to spend some time on the various off-grid related sites (grass roots technology), but never can find the time. Probably some very interesting stuff there.
The investment is well into to thousands for a good system. My goal here is to play devil's advocate and suggest that folks really do their homework into the many factors that can impact their decision/investment.
Jim
Theres a neighbor down the road has a small wind generator, I mean small, about a 3 foot fan, and looking at it noted the fan was stuck onto a GM Alternator. ??? On the other side of his garage roof, where you cant see from the road, he has half the roof covered with solar panels. He said it started with one, and grew. Inside the garage he has a bank of car batteries. None match, but he said their all even and all being charged through a controller. None of its fancy, most of it looks crude/hobbiest, but its working. He has a couple inverters providing AC power to the house on seperate panels, said all his TV/audio/video is running solely off his system, as are most of his lights, all the garage lights, garage door openers, and his refrigerator. He said the wind electrics were what he started with, but the solar has so greatly surpassed them he no longer uses them.
While on the one hand this stuff appears greatly complex and difficult to calculate, on the other hand this guy has shown that you can just start building and working it out as you go. The parts are readily available, getting cheaper by the day, and its not rocket science.
My thoughts for the Bus, if I could do it economically, would be to cover the entire roof with panels that fit the contour, and accept whatever it could deliver. No matter what it provided, any time it took away from running the generator would be some kind of payback.
Yes, I know what you mean about wanting to just cover the roof with panels and get what you get. The contour of our curved roof doesnt go great with flat panels either... That's one reason I was looking into making my own panels. Instead of the usual rectangles they could be rows, so it was kinda striped up on top of the bus and kerfed going around. The air gap created would help with insulation too. Maybe spoilers or something could be added up there to help wind resistance......
CamperBrat
Where were you looking to source your cells from? The process of building a custom array intrigues me.
Brice
For what it's worth, arrays don't respond well to being partially shaded and generally incur significant losses unless insolation across the array remains nominally equal.
Quote from: JWallin on May 13, 2011, 10:22:19 AM
For what it's worth, arrays don't respond well to being partially shaded and generally incur significant losses unless insolation across the array remains nominally equal.
just so im understanding you, are you saying the shaded cells suck power away from the producers? Couldnt the roof be made up of many mini cells, all connected in groups, then each group routed to some type of controller or bank of diodes? I thought if I was ever dumb enough to cover the roof with solar cells, odds are its going to get damaged by falling branches, hail, etc., so best to think small cells rather than large big dollar ones.
When even a small portion of a cell, module, or array is shaded, the output falls dramatically due to internal short-circuiting which results in heat being produced instead of power. Most individual panels contain bypass diodes to reduce this effect. Solar panels are many "mini cells" grouped togeather and routed to some type of controller. So while different configurations may influence both initial and ongoing balance of system costs, shading remains a consideration.
Quote from: babell2 on May 13, 2011, 09:39:01 AM
CamperBrat
Where were you looking to source your cells from? The process of building a custom array intrigues me.
Brice
Hi Brice! My brother is getting them from ebay... they sell them single celled. Watch the packaging though when buying this way. They are extremely fragile, kinda like handling a saltine cracker so they can break very easily.
Between falling tree branches and hail, without some kind of laminate over them I forsee some cell damage to contend with. But poking round on ebay, wow, looks like about $20-$25 square foot, averaging about 5.5 watts output per square foot. On a 35 footer thats almost $9000 in cells, and with perhaps 60% max output (thinking parked most un-optimally) just over 1100 watts of max energy per hour. Quite an investment. But only if you could use the available power to full advantage, and "if" the system had a reasonable and well known life expectancy could you determine the pay off time.
More fuzzy math? Say you average 60% output 6 hours a day, so roughly about 6.6 KWH of energy. To accumulate the cost of electric ($9000) from the utility, using $0.10 per KWH, your system would have to provide 90,000 KWH. If your $9000 system only averaged 6.6 KWH per day, every day, it would have to run 37 years to match the same rate from the utility.
And of course, were doing this to have the luxury of not plugging into utility power, and also in which case what were really trying to do is not run the generator. Were likely going to have a Genny anyway, so its aquisition cost is moot. So say were looking at providing the same energy from the Genny, 1.1 KWH, and figuring my lil 8KW genny will burn close to half a gallon an hour no matter what, and disregarding maintenence, the cost would be around $12 day. To break even on fuel, the system would have to produce power at that level for 750 days. Just past the two year point.
These are all simple assumptions. Parking the Bus fully east/west in a clear area would provide more energy, and surely we would get more than 6 hours per day, and both would increase the available power that could be used. But also, when were not in the Bus, all that power is going to waste, eating up time, etc.. About the only real advantage is not running the genny, but your never going to save one penny doing it. OTOH your genny isnt paying off sitting idle either, its simply another form of investment. Now if the Bus is your home, and your living aboard year round, and spending a lot of time unplugged, it would make much more practicle sense.
Very interesting and thought provoking discussion.
Quote from: artvonne on May 14, 2011, 10:12:27 AM
... with perhaps 60% max output (thinking parked most un-optimally) just over 1100 watts of max energy per hour. ... Say you average 60% output 6 hours a day, so roughly about 6.6 KWH of energy.
Whoa there. First off, there is no such thing as "watts per hour" -- watts are already a rate, so it is just plain "watts."
As I wrote in the post that Jim linked, the average energy delivered by a single watt of PV is 3 watt-hours. So your nominal 1,100 watts of PV panels will deliver around 3.3 KwH, not the 6.6 you suggest. These are well-understood and well published numbers; there is no need to be guessing at them on this board. The math does work out much better if you conveniently double the efficiency of the panels, though :)
Note the average of 3 watt-hours per watt of panel assumes completely unshaded panels set at optimal angles, so on a coach the number will actually be a fair bit less.
FWIW.
-Sean
http://OurOdyssey.BlogSpot.com (http://ourodyssey.blogspot.com)
Is a panel rated at 68 watts, not going to produce .068 KW? I assumed it would work the same way as figuring the KWH for a 60 watt light bulb, ie; 60 watts/1000=.06KW, and if used for one hour would equal .06KWH. Or is that wrong?
Or did I word it wrong? Ive read this stuff and thought I had a handle on it, but maybe I missed something. Ive read panels produce around 8 to 10 watts per square foot, so 350 square feet of Bus roof (curvature is roughly 10 feet edge to edge), you should have potential of 3500 watts. However, the panel I was using for calculation purposes was a flexible panel rated at 68 watts, and covered 12.4 square feet, producing about 5.7 watts per square foot. I downrated it to 5.5, and calculated that on 350 square feet of roof it might produce 1925 watts. But as a curved roof will never fully face the sun, I downrated to 60%, or 1155 watts, and rounded down to 1100. I made the assumption that if the roof produced 1100 watts per hour, that would equal 1.1 KWH of potential output. No?
Before you waste any more time, go find a graph or chart showing the efficiency loss as the solar panel is inclined away from optimal to the sun, both in the vertical and as the sun tracks across the sky.
And then you'll see why you are having trouble finding coaches covered in solar cells.
Arbitrarily choosing efficiency numbers without sound research doesn't inspire informed discussion, it's just noise.
Sometimes, the place to start is those researchers who have gone before using good scientific methods, not internet bulletin boards.
happy coaching!
buswarrior
Quote from: artvonne on May 14, 2011, 06:31:18 PM
Is a panel rated at 68 watts, not going to produce .068 KW?
No, it's not. At least, most of the time it won't, and it might never.
That number is for "ideal" conditions, meaning at high noon, facing straight up, at the equator, on a completely clear day, with cool air (70°F) flowing both above and below the panel.
In the real world, you are not at the equator, and the panels, if they ever face the sun directly (almost never on a coach roof), only face the sun exactly once each day. The rest of the time the panel is producing a fraction of its rated output.
Between this and the fact that "average" conditions include partly cloudy days, the average PV panel produces, as I said, about 3 watt-hours per day for each rated watt (in the continental US). IOTW, a 100-watt panel can be expected to produce about 300 watt-hours of electricity each day. Even under the most ideal conditions, meaning a tracking panel at the equator on a clear day, the angle of incident radiation is only optimal for a few hours per day.
-Sean
http://OurOdyssey.BlogSpot.com (http://ourodyssey.blogspot.com)
If you are wanting solar because you are concerned about generator noise, why not sound insulate the generator? I've stood beside one that made less noise than a box fan.
If you want to keep your batteries up while you are away, that is a different issue, but could be tied into a low battery start of the generator to charge them . . . .
The last time I dove into solar panel research, the cost vs benefit was way too high for my situation.
As for the guy building his home system as he goes - that sounds like a fellow I used to work with. Building that solar system was a hobby for him. It worked fine as long as he was there to tend to it - but output suffered greatly when he wasn't tinkering with it.
YMMV
Quote from: buswarrior on May 14, 2011, 07:25:14 PM
Before you waste any more time, go find a graph or chart showing the efficiency loss as the solar panel is inclined away from optimal to the sun, both in the vertical and as the sun tracks across the sky.
Arbitrarily choosing efficiency numbers without sound research doesn't inspire informed discussion, it's just noise.
happy coaching!
buswarrior
Perhaps if you had that knowledge, or data, you could share it?
Free lunch is over, you need to meet folks at least part way down the road.
Sometimes, the place to start is those researchers who have gone before using good scientific methods, not internet bulletin boards.
happy coaching!
buswarrior
Because this discussion has polarised into two diametically-opposed camps, let's hear from anyone in bus-land who's actually using a solar system (either PV or water heating) on their bus. We need to know if it meets their expectations (and what those expectations are), how much it cost, how much it produces, is it home-grown or off-the-shelf, where they are (the sunny Southwest or the Great White North?), if it's an adjunct to or a replacement of another setup, etc etc. This whole subject reminds me of the bumblebee - shouldn't fly in theory, but somehow it does.
Something relevant here is whether one wants more-or-less conventional loads such as RV air-conditioners and standard fridges, or whether one will accept less-conventional alternatives such as simple evaporative coolers and chest freezers used as fridges ("fridgers"). In other words, what fundamental change of lifestyle is acceptable? What's OK for one person may be laughably deficient or excessive to someone else.
John
For what it's worth, we find that solar panels(electric) work for us. We started out to reduce generator hours, which are not real cheap, and we decided that the panels would not be expected to do heating or cooling directly other than occasional use of the microwave.
We installed four 55 watt panels that are 13" wide, which allowed us to have a path between them for us to walk on the roof of the coach. We use a Xantrex 2500 inverter/charger and a low cost MPPT charge controller with temperature compensation and we normally have 500 lbs. of batteries. Do not omit temperature compensation; you will be disappointed, if you do.
This gives us nearly a week between generator sessions, which is ideal. When we are in hot country, we figure on plugging into shore power when parked. In cold country, we can get by with a generator session every three days using a propane furnace.
It's not perfect, but it's a good compromise for us. Experimenting is pretty easy from this point.
Tom Caffrey
sounds like a small amount of solar panels to supply energy for the basic electrical demands is okay, but for the heavy duty cooling or heating we just arent there yet...... and to cover the roof with cells would be overkill on the pocket book without a decent return....sigh
Quote from: buswarrior on May 14, 2011, 07:25:14 PM
Before you waste any more time, go find a graph or chart showing the efficiency loss as the solar panel is inclined away from optimal to the sun, both in the vertical and as the sun tracks across the sky.
And then you'll see why you are having trouble finding coaches covered in solar cells.
Arbitrarily choosing efficiency numbers without sound research doesn't inspire informed discussion, it's just noise.
Sometimes, the place to start is those researchers who have gone before using good scientific methods, not internet bulletin boards.
Free lunch is over, you need to meet folks at least part way down the road.
In this entire thread youve added NOTHING to the discussion, your only comments were directed solely at me, and they are belittling and sarcastic. And its not the first time. But it IS the last time. Sir, from here on out, either put me on ignore, or simply ignore me, and I will do the same.
Thanks for all the input from everyone ,I've been playing around with solar stuff on the bus for about a yr and a 1/2..I started out with 2 100watt panels and a mppt controller ,3 rv/marine 105 amp hr batteries ..a 1000 watt inverter ,,,found out the batteries and the inverter could not keep up...now I have 7 100 watt panels on the roof ,,a 3000 watt inverter ,and 8 6v gel cell batteries ,,40 amp xantrex controller/charger ,,now after 2 grand kids and 10 days of sitting in the yard ,,everything works ,runs just fine ,frig ,lights water pump ,tv and I even made some coffee yesterday ,,,by about 3pm the batteries are charged up and the controller is on float,,we have not used the generater at all ,,no a/c,,I know I don't have enough power to run them,,As for money invested ,,I got most of the solar stuff from ?raigslist and ?bay ..if you shop around ,there are some pretty good deals out there,,I got the panels for 150 ea,,the batteries came from an elec contractor, used cell tower Deka 6v gel cells 35,dollars ea,,the inverter 120 dollars,,now hopefully ..I'll only have to run the gen for a/c..none of its very high tech ,,but it seems to be working for me ,,anybody else using solar for backup? Swap some ideas on differant ways to make it work better,,One thing that I have learned ,,use big wires from the panels to the controller and batteries ,,fuse everything ,,,still in the learning phase,,,thanks ,pete
Sorry that my advice as to your next steps have been interpreted as offensive.
Perhaps in much the same manner, I have interpreted your posts as someone who is looking for answers without wanting to do the work, instead letting others invest the time to find them for you.
So, now we may both go away chastised and misunderstood.
happy coaching!
buswarrior