My thread on "Do Solar panels really Work" seems to have lost the topic a little, so I'm starting a new one. It appears the average fit-out of panels is about 250W and it seems two deep cycle batteries of about 100 AH each.
However the way I see it, the batteries are charged by the towing vehicle while on the move, and then charge regulated by the site power by the battery management system when camped at a powered site.
So do you guys use unpowered sites, unless free camping, if at a powered site, what do your solar panels do?
Of course at "Free powered sites" the solar panels and/or generator would be required.
Hi iana, to just simply answer your question, I get a powered site then I can use my fridge on 240v and run the aircon if needed. I mostly free/alternative camp in my aluminium tent though.
Whatever you do or wher ever you stay just enjoy and keep safe.
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TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy
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If the solar panels are mounted on top of the caravan, then the batteries should be charging while you are driving. If they are inside the caravan and mounted when you stop, then the only charging is from the vehicle.
Reed and Elaine
So I guess my next question would be, do you disconnect your vehicle supply from the battery when on the move. How else do you know what contribution the solar panels are making when traveling?
I stress I am NOT a Techie However, this is how I understand it all works.
I have a 240 inbuilt smart charger - charges the house battery when on 240V
I have an Anderson plug on vehicle - charges the battery when driving.
I have 2 X 80Watt solar panels on the roof. This is connected to the battery by a Controller. This controller is constantly checking the charge of of the battery and if needed puts the "amps" in to keep it charging (or topped up). This is whether stationery camped or driving - if there is sun on the panels they are "ready" to put "amps" into your battery.
You don't need to disconnect either the 240V inbuilt smart charger, or disconnect the vehicle charge .. the solar panel controller will make the decisions for you. It is the State of Charge of the battery that will determine whether the controller lets "amps" through to the battery or not.
Obviously, when it is sunny while you are driving the solar panels will put charge into the battery if required ... but if it is overcast or raining etc, then the vehicle's charging system will be providing more charge than the solar panels, therefore vehicle will provide the charge.
Techies - feel free to correct any errors in the above.
Cheers - John
-- Edited by rockylizard on Saturday 3rd of January 2015 11:45:25 AM
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I guess I could come clean and explain that the power from solar panels is not the only thing I am thinking about. This new van will cost me around about $130,000, so I think I am entitled to look at all aspects of its design, and not just except what I am told I should have, just because its convenient for the manufacturer.
I have an aircraft engineering background, and as such, was taught a fair bit about drag. I don't know how many of you realize, but drag or resistance to forward motion goes up at the square of the speed. So long distance journeys at 100km/hr, any add-ons will have an effect on vehicle fuel consumption.
I've had a look at the roofs of a few new vans and it looks a real dogs breakfast up there, and of course you don't see it from the ground, and what the eye don't see the heart don't worry about.
While I agree any induced drag on the roof will be minor compared to that caused by the flat back of the van, a smooth roof would have some effect on reducing drag. One item of equipment that must cause considerable drag is the air con, no attempt at streamlining, and is just a convienence package for the installer. I was quite surprised when "SnowT" mentioned installing a domestic air con. By putting the condenser on the back of the van in the dirty air, this would clean up the roof. Off setting this is the increased cost of installation, and loss of storage space.
The vents are also not designed to be streamlined either, and of course we come to the solar panels, stuck on the roof at any convenient spot, wires and brackets everywhere.
So what we could have is a saving in fuel when traveling by harvesting solar energy, but off-set by the increase in drag and increased fuel consumption. Result, no advantage. You just have to look at the effort car manufacturer's have gone to make their designs aero-dynamic.
However by using removable panels, and I'm only thinking two panels weighing about 11kg each with quick connect fasteners so they can be attached at a slight incline front or rear of the van when using free camping, or non powered camp sites, would not take that much effort to install each time, but would have the advantage of harvesting more sun energy earlier in the day or in the winter time. But resulting in a tidier roof.
Of course I am only throwing this up for discussion, its along way down the track before I settle on any designs.
Something to also add to your calculations may be just how much time/Km the van spends on the road.
Using my lifestyle as an example - and there are infinite variations on my vanning lifestyle.
I travel each year, on average, between 350/420km per week. I spend at least five days each week camped using the solar panels to recharge the battery. The van obviously remains stationery. Sometimes the van is stationery using solar for upto three weeks.
Some times, I only travel 80km in a day - sometimes 300km over two days. I travel at 85-90kph rather than 100Km.
Given the van remains stationery for about 80% of the year providing my power, would the drag 'impact' over a year be worth considering - let alone calculating?
I don't know the answer - but perhaps a manufacturer, under public pressure?, should invest is the use of a wind tunnel
Cheers - John
__________________
2006 Discovery 3 TDV6 SE Auto - 2008 23ft Golden Eagle Hunter Some people feel the rain - the others just get wet - Bob Dylan
I stress I am NOT a Techie However, this is how I understand it all works.
I have a 240 inbuilt smart charger - charges the house battery when on 240V
I have an Anderson plug on vehicle - charges the battery when driving.
I have 2 X 80Watt solar panels on the roof. This is connected to the battery by a Controller. This controller is constantly checking the charge of of the battery and if needed puts the "amps" in to keep it charging (or topped up). This is whether stationery camped or driving - if there is sun on the panels they are "ready" to put "amps" into your battery.
You don't need to disconnect either the 240V inbuilt smart charger, or disconnect the vehicle charge .. the solar panel controller will make the decisions for you. It is the State of Charge of the battery that will determine whether the controller lets "amps" through to the battery or not.
Obviously, when it is sunny while you are driving the solar panels will put charge into the battery if required ... but if it is overcast or raining etc, then the vehicle's charging system will be providing more charge than the solar panels, therefore vehicle will provide the charge.
Techies - feel free to correct any errors in the above.
Cheers - John
-- Edited by rockylizard on Saturday 3rd of January 2015 11:45:25 AM
Hi John
Pretty goodjust a litle extra .
When the batterries are accepting BULK charge
ie in a low state of charge both will be contributing. if it is all a direct wired system or even with a simple DC/DC charge [not one has a solar input set of terminals & you]
As the battery appproaches fully charged, one or the, other solar or alternator will cut out..
Leaving one to finish of the charging or even supply the loads
That may even include normal vehicle load
Quite often ,when that stage is reached, the one that was "OFF will start cycling "ON" & "OFF"
That Is not a problem,but it may lead to some concern as the alternator light may flicker "ON" & "OFF"
PeterQ
-- Edited by oldtrack123 on Saturday 3rd of January 2015 02:04:38 PM
Hi Ian, I doubt if you will ever achieve a drag free roof, but using light weight panels mounted down close to the roof may help.
The two images below show the roof of our van, the solar is mounted down close to the roof, and the air con is gone, replaced by a split system mounted on the back bar. BTW, it is cheaper to go for a split system than a roof mount, they are much cheaper to buy, and easier to fit.
I do realise that mounting the panels on top of 10mm of insulation as we have done traps the heat in the panel, and reduces the efficiency of the panel. Our panels get to about 75 degrees, and by then they are only about 80% efficient, add this to the fact they are sitting flat, and efficiency probably drops to about 40% across the day. We overcame this by having more panels. There are twelve 100W panels on the roof, and we are typically back to 100% charged mid afternoon. If we have used the air through the day, it may be later.
Something to also add to your calculations may be just how much time/Km the van spends on the road.
Using my lifestyle as an example - and there are infinite variations on my vanning lifestyle.
I don't know the answer - but perhaps a manufacturer, under public pressure?, should invest is the use of a wind tunnel
Cheers - John
Thanks John.
Yes I think that life style would be pretty good. Its not really the distance you travel that makes the difference, but the speed at which you travel during the journey.
Now the idea of putting the van in a wind tunnel would probably produce some rather horrific results, and finding a manufacturer willing to do this would be scarcer than hens teeth.
I,m glad that nobody has labelled me as completely Looney, partially maybe but!
Suppose you were towing your van a 20km and had a drag factor of 1, if you then travelled at 100, the drag factor will have risen to 80 squared or 6400. I think that's right, anyone can correct me f I'm wrong, not great on mathematics.
This would reflect directly as fuel consumption.
-- Edited by iana on Saturday 3rd of January 2015 05:17:52 PM
Hi Ian, I doubt if you will ever achieve a drag free roof, but using light weight panels mounted down close to the roof may help.
The two images below show the roof of our van, the solar is mounted down close to the roof, and the air con is gone, replaced by a split system mounted on the back bar. BTW, it is cheaper to go for a split system than a roof mount, they are much cheaper to buy, and easier to fit.
The amount of drag produced by the back of the van being "sawn off" would be massive, and yes to produce a drag free roof, would be asking a lot. You would agree that the air con is quite a drag producer, and I agree you have gone along way to reducing the effects of drag over the roof.
It would be interesting to find out how many travellers have converted to domestic air con's and what if any problems they have had. I may have to start a separate tread on that.
Hi iana, to just simply answer your question, I get a powered site then I can use my fridge on 240v and run the aircon if needed. I mostly free/alternative camp in my aluminium tent though.
Whatever you do or wher ever you stay just enjoy and keep safe.
So the girls live in a tent now, i hope you have a BIG tepee. Happy New to all at Greens from both of us. OOOPPPs off the topic YOU do teach us well. cheers
-- Edited by reglynn on Saturday 3rd of January 2015 10:43:36 PM
If you are seriously worried about drag and All that is involved.. Have you taken into account the weight you will e dragging along...??
The weight of the batteries will come into affect... Let alone what you have mounted on the Roof... Are you oing to have a SMOOTH under floor or are you going to leave it as the manufacturer leaves it..
The Amount of Drag you would get off a set of Roof mounted Solar Panels in Tiny Compared to the amount of drag turbulence you would get off a ROOF mounted Air Con... = Are you going to shape the front of the van so it has a linear airflow, or even going to make the whole setup so the connection point from Tow Vehicle to Van has minimal effect...??
Are you going to have some thing to help break the Drag effect as the Air Leaves the back of the VAN..?
Sorry the information you are after does not seem to compute...
The van you will be towing is as streamlined as a rough brick. The additional drag imposed by solar panels or A/C unit will be IMHO inconsequential in the overall scheme of things.
methinks you are worrying unnecessarily.
frank
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Thanks for photograph of what I think is the split level exchanger on the roof. If we removed the high a/c on our 34' (10 m) fifth wheel, we could install two more x 235 W panels.
Reed and Elaine
we ha v a sunland caravan, with 2 x200w solar panels and 35 amp smart charger.
when drivivg car runs fridge, solar charges battery. When at cp on 240 v solar does not charge battery unless smart charer turned off from 240v. Fridge and aircon use 240v.
so when on 240v and smart charger charging battery, solar panels do not operate, controlled by solar controler
Thanks for photograph of what I think is the split level exchanger on the roof. If we removed the high a/c on our 34' (10 m) fifth wheel, we could install two more x 235 W panels. Reed and Elaine
Hi Reed,
it is a long time since I have seen you on the forum, sorry but there was no AC on the roof at all, just solar panels (12), vents (4), and a TV antenna. The compressor part of our split system is on the back bumper, see below:
Thanks for posting the photo. We have plenty of room on back and front of our 10 m 5th wheel to mount such (one for bedroom and/or livingroom. This would free up the roof for 3 more 235 W panels (son buys them by the multi-pallet load and cost him about $.50 US or less a watt. The Dometic A/C is an energy hog at 1750 W.
Next question: How much energy in watts does a split level require.
Currently, we are not moving much. Still have problems resolving issues with Mexican customs from wreck of 21 months ago so we are not going to Mexico, Belize and Guatemala again till next year. Will just fly to Ecuador and Peru since Machu Picchu and Galapagos are the top two on Elaine's bucket list (and we are 74). Have a friend from Army Ranger days who lives in Paraguay and might visit there as well. Two of our best friends shipped their pickup camper to Columbia and got totally lost in the mountains at 12,000' in cow pastures - have shipped pickup camper back to Galveston, TX and will be headed down into Mexico. Did 8000 miles in the US Northwest (Olympic and Glacier National Parks, Blackfoot Reservation, family and friend, and then spent the rest of the year with both sons and daughter. Such days do not come back.
Thanks for posting the photo. We have plenty of room on back and front of our 10 m 5th wheel to mount such (one for bedroom and/or livingroom. This would free up the roof for 3 more 235 W panels (son buys them by the multi-pallet load and cost him about $.50 US or less a watt. The Dometic A/C is an energy hog at 1750 W.
Next questions:
How much energy in watts does a split level require.
What does the heat exchanger look like on the inside
Currently, we are not moving much. Still have problems resolving issues with Mexican customs from wreck of 21 months ago so we are not going to Mexico, Belize and Guatemala again till next year. Will just fly to Ecuador and Peru since Machu Picchu and Galapagos are the top two on Elaine's bucket list (and we are 74). Have a friend from Army Ranger days who lives in Paraguay and might visit there as well. Two of our best friends shipped their pickup camper to Columbia and got totally lost in the mountains at 12,000' in cow pastures - have shipped pickup camper back to Galveston, TX and will be headed down into Mexico. Did 8000 miles in the US Northwest (Olympic and Glacier National Parks, Blackfoot Reservation, family and friend, and then spent the rest of the year with both sons and daughter. Such days do not come back.
Pretty much gleaned all I need from this thread, but a separate thread on split domestic air cons used in caravans would interest me, although I have pretty much decided on an Air-commander Ibis 3-2.
However, this is how I understand it all works.
just a litle extra .
