Installed solar panels do they really work?

iana · Guru

Installed solar panels do they really work?

Delta18 · Guru

Thousands of people, like us, have solar panels mounted on their roof too and have ample power for all their needs.

Provided you have enough panels and sufficient batteries to store the generated power you will have no problems.

In your hypothetical shady caravan park you would probably be on a powered site anyway. Modern panels run through a MMPT controlled will get aa lot of power in the shade anyway.

Our travelling more often than not is done in winter months and we totally rely on our 2 x 150w panels feeding 2 x 105AH deep cycle batteries.

Cheers Neil

WAssa41 · Senior Member

If you install solar on your roof think about may be installing them at each end of the caravan, most times you have one end in the sun and I would also think about a portable unit as well, this way you are totally covered no matter where you stay,

Wassa

iana · Guru

I guess what I forgot to mention was, we intend to live in the van for at least a couple of years. For Joe Blow who is just going for a weekend camp this issue of the solar panels, would make very little difference. Also the trips would be made typically during the summer months when the sun is higher in the sky.

However during the winter months with the short days, power consumption is at its maximum, conversely with solar power generation, daylight hours are at the shortest, as well as the sun being low down.

Bruce and Bev · Guru

we have 2 x 80w panels on our van roof and 2 x 105 batts. The most important thing for roof mounted panels is to keep them clean and so we have a 5ft ladder tied to the rear bumper so I can climb up and give them a wash off about every 4 weeks or so (dust and bird droppings). If you don't keep them relatively clean, power generation drops substantially. At night we have around 4 of the large ceiling mounted LED (big power savers) lights on and the TV on for about 3-4 hours and it runs just fine.

Obviously bigger charging panels are better along with more batts - but the latter take up space and both add weight to the van. We haven't needed to supplement our panels with portables - remember they are very stealable and you need to turn them to follow the sun during the day to get maximum batt charge.

Also consider what type of panel you will use - there are two and both have pros and cons. One works better in heat and strong sun and the other type works better in semi shade.

I also carry a gen just in case. If the weather is not good - charge the batts this way - doesn't take long to bring them up to full charge

kirraweebob · Veteran Member

We have 1 x 120W solar panel fixed to the roof of our van and 1 x 140W folding panel with a long lead on it to an Anderson plug. With 2 x 120Ah and the original 85Ah Battery in our AVan connected to a 300W and a 2000W Pure sine wave inverters and we ran from 2 Jun 2014 to 11 Jun 2014 when the weather was absolutely atrocious and the sun was lost!

We used our power for nespresso machine (essential for us coffee lovers) 4 times a day and the microwave 4 times for 30 secs each (to heat the milk for the coffee). Our normal 240V TV, satellite receiver, lights (we replaced original globes with LEDs), charging of computer and iphones etc and it did well. Only time we had a low battery indication was after we used 20 minutes of microwave to cook a meal as it was pouring rain outside. But the system recovered over a few days. Depends on space and weight restrictions but you could add more batteries and extra panels to charge them quickly.

There are also other threads in this techies forum where they indicate how to calculate your needs (effectively daily use in total times three). Agree with Bruce and Bev on the generator just in case. Will have one when we upgrade to a new van next year.

Hope our cloudy winter experience gives you some assistance.

moblet · Senior Member

iana wrote:
However during the winter months with the short days, power consumption is at its maximum, conversely with solar power generation, daylight hours are at the shortest, as well as the sun being low down.

What appliances will you be running from your batteries? If your refrigeration is electric then your power consumption will likely be at its maximum in summer. LED lights use relatively little power so the extra hours of lighting in winter are insignificant in comparison to refrigeration.

Karlene · Member

We have 3 x 140W panels, a MPPT controller and 2 x 120Ah AGM batteries. Fridge runs on gas, LED lights everywhere. Also added a 2500W inverter to run the toaster and microwave. We have heaps of power for our needs. Even when cloudy and even 8am with little sunshine the panels charge the batteries. To date the batteries have been always been fully charged by about 9am. Best to do a bit of study on solar systems, estimate your needs and then instruct your builder on what you want.

SnowT · Guru

Greeting and welcome to the forum's..

Installed Solar Panels Do they Work..

- that is a nutty question, dependent on many factor's..

In a simple world Yes they will work, but are dependent on many factor's..

- It far better to have more Solar Panels than you actually need...
I have 1200W of Solar and by the time I finish the modifications to my system I will have 1600w's of Solar...
In a nut shell the amount of energy that the panels gather is dependent on Where you are in Australia and time of the year..
- During Summer the sun id Higher, even in the lower states.. Winter the Sun is not as high...

So you allow for those times of the year..

My1600w ill equate to about 1120w's of solar @ the best of time's.. or About 800w's at winter time..

My solar panels also act as a Tropical roof for my Bus.. and I'm running an all Electric Bus 12v/24v/240v..

One thing with your Build Look at installing normal Domestic Split Aircon system as they are more effiecient than the off the shelf Caravan/RV Aircon system's.. Plus they don't take up Roof space... and they are also 1/2 to 1/3 the cost of the sytems you have std Van's RV's..

Also Look at the Possibility of using a DOMESTIC[House] Fridge.. Same reason's again..

I'm not going into the types of Batteries. But I will say Do the research on ALL types of Batteries..
LEAD ACIDS are not the only Batteries out There.. SEND me a PM for what I'm using..

Juergen

Andrea · Senior Member

Hi, iana - and welcome aboard!

We had our 5th-wheeler built in Brisbane in 2008, with three 105 w solar panels and two 120 a/h AGM batteries. That is sufficient to run everything we need (though not the air con or microwave - we haven't bothered!), which includes our 12 v compressor fridge, all lighting, TV/radio, etc. and our Fantastic fan. We use a diesel heater, and gas for cooking and hot water. Never had any problems and fully recommend such a setup.

Cheers -

Andrea & John

Plendo · Guru

Hi iana, and welcome to the forum.

To address your initial concern, do roof mounted panels work?

The answer has to be yes, but not nearly as well as a panel that can be aimed at the sun.

If you use panels mounted on a tracker as the benchmark, then manually adjusted panels will be about 85% efficient, and panels mounted flat on the roof maybe 45 to 55% efficient.

However it is significantly easier to have two panels on the roof, than to have one manually aimed portable panel. Firstly you do not have to be there all the time, second you do not need to worry as much about someone "borrowing" them, you do not need to find storage for them, they keep charging when you are moving, etc.

There are lightweight panels available now, so you do not need to worry about adding a lot of weight to the roof. All up weight of panels and cables would be approximately 1.5kg per 100W with the lightweights, and maybe 12Kg with the traditional glass fronted panels.

In my example I have twelve 100 watt light weight panels on the roof of the van, and we have easily harvested 85 amp hours at 24 volts equivalent to 170 ah at 12V) by 4pm on a bright sunny day (at Greens Lake last week). I believe it would happily have harvested 120 ah for the whole day, but the battery was full. BTW, 120 AH across 7 hours would be about 30% efficient.

I hope this helps with your decision.

iana · Guru

I really haven't got that far yet, i.e. working out the loads etc, my main thoughts are at the moments spending say $5000 on roof top fixed panels, is that the way to go.

Thankyou for taking the time to reply. P.S. I haven't finished yet though!

This post didn't go to where I wanted it, it was aimed mainly to moblet

-- Edited by iana on Wednesday 31st of December 2014 03:30:13 PM

iana · Guru

Looks like you have got a southern Cross which is what we are looking at getting. I think I have shots of your van on my PC sent cutesy of Barry.

Bugger me how do I do this, this reply was to Andrea & John

And also thanks for the reply.

-- Edited by iana on Wednesday 31st of December 2014 03:33:06 PM

Delta18 · Guru

iana wrote:
my main thoughts are at the moments spending say $5000 on roof top fixed panels, is that the way to go.

-- Edited by iana on Wednesday 31st of December 2014 03:30:13 PM

You would get a truckload of solar for $5000, at less than $2 per watt including cables, controller & a couple batteries you could get around a 2kw system that you would run anything anytime.

iana · Guru

I am having fun here, Its okay moderators, I know some of the folks on here may have delicate tickers, but mine is not that flash either. you see its a case of asking the question "Why". Ever since I was knee high to a grass hopper, I have been asking the question "Why". Just ask my present boss, when I say " now I've been thinking" I know he's thinking "what the hell is he coming up with now".
And yet I come up with some pretty wiz bang solutions to situations that we have just put up with, just because someone else has said that is the way it is, until I interrupt and ask "Why".
Now in this post I have not mentioned portable panels, that has just been an assumption by those who are saying if they are not fixed then they must be portable. But yes technically I am thinking of portable panels, but thinking outside the square, what if the panels can be mounted on the roof, but can be orientated for the optimal ( note , I did not say best), efficiency?
Still mounted on the roof, hence can't be stolen, maybe packed away prior to moving, or left fixed flat, still to be explored.
Just remember I am intending to travel to a spot, camp for a week or so, I have plenty of time to set up, life is going to be a dream. Provided I've got the design of the van right!

PS I don't have a sense of humour, nor do I have any sense.

-- Edited by iana on Wednesday 31st of December 2014 03:56:08 PM

iana · Guru

moblet wrote:
iana wrote:
However during the winter months with the short days, power consumption is at its maximum, conversely with solar power generation, daylight hours are at the shortest, as well as the sun being low down.
What appliances will you be running from your batteries? If your refrigeration is electric then your power consumption will likely be at its maximum in summer. LED lights use relatively little power so the extra hours of lighting in winter are insignificant in comparison to refrigeration.

Spot on. I hadn't thought of that.

Thanks for the reply.

Andrea · Senior Member

iana wrote:
Looks like you have got a southern Cross which is what we are looking at getting. I think I have shots of your van on my PC sent cutesy of Barry.
Bugger me how do I do this, this reply was to Andrea & John
And also thanks for the reply.

biggrin biggrin biggrin Not to worry, iana - we've all been there! If you want to respond to a comment by one poster, click on 'QUOTE' (top right of each post). That's what I've done here. You don't even have to leave the whole quote there, you can just delete the irrelevant bits.

Yes, ours is a Southern Cross, no.11, which we ordered at the show in June 2008. Never regretted it, we LOVE our home. Would love to see what you're getting when you decide. And say hello to Barry and John from us! If you'd like to discuss any further or ask anything about SC, send us a PM (private message).

Cheers -

Andrea & John

Andrea · Senior Member

iana wrote:

Now in this post I have not mentioned portable panels, that has just been an assumption by those who are saying if they are not fixed then they must be portable. But yes technically I am thinking of portable panels, but thinking outside the square, what if the panels can be mounted on the roof, but can be orientated for the optimal ( note , I did not say best), efficiency?
Still mounted on the roof, hence can't be stolen, maybe packed away prior to moving, or left fixed flat, still to be explored.
Just remember I am intending to travel to a spot, camp for a week or so, I have plenty of time to set up, life is going to be a dream. Provided I've got the design of the van right!
PS I don't have a sense of humour, nor do I have any sense.

Ours are mounted on the roof of our van, iana - and even on cloudy days we still get plenty of charge to the batteries. On top of that, we tend more to the southern half of the continent so, theoretically, get the sun at a greater angle.

Andrea & John

iana · Guru

Andrea wrote:
iana wrote:
Looks like you have got a southern Cross which is what we are looking at getting. I think I have shots of your van on my PC sent cutesy of Barry.
Bugger me how do I do this, this reply was to Andrea & John
And also thanks for the reply.

Not to worry, iana - we've all been there! If you want to respond to a comment by one poster, click on 'QUOTE' (top right of each post). That's what I've done here. You don't even have to leave the whole quote there, you can just delete the irrelevant bits.
Yes, ours is a Southern Cross, no.11, which we ordered at the show in June 2008. Never regretted it, we LOVE our home. Would love to see what you're getting when you decide. And say hello to Barry and John from us! If you'd like to discuss any further or ask anything about SC, send us a PM (private message).
Cheers -
Andrea & John

I get the impression Barry is not all that happy with me. I'm aiming for the more traditional layout of van with the bed over the goose neck and a lounge at the back. My reasons are that I wake up at all hours of the night, and have to get up and do something. with the bed in the goose neck and the lounge at the other end we would disturb each other less. Also there are caravan parks that butt up against magnificent scenes, my idea is that one can sit in the lounge and admire the view. What are your views on this?

moblet · Senior Member

iana wrote:
what if the panels can be mounted on the roof, but can be orientated for the optimal ( note , I did not say best), efficiency?

I've read of people doing this, can't remember where, it might have been here or it might have been on a North American-based forum on mobile living. I think it was a basic hinged arrangement, possibly forming an awning, but anything's possible if you've got enough money to throw at it.

A few considerations for such a setup:

- You're not going to be able to park with the same orientation everywhere you go. Therefore, unlike fixed tilt/tracking systems you're likely to need a greater range of motion or accept that not all your panels will be optimally aligned.

- The most productive hours of solar production are the 4-5 hours in the middle of the day, which also happen to be the hours when you're most likely to want to be in the shade, and if you are in the shade then the high sun means your panels will be in the shade no matter which way they're pointed. I see where you're coming from though, that if you're parked for noon-day shade you're probably receiving sun mid-morning and/or late afternoon and flat-mounted rooftop panels are poorly aligned to harvest it.

- Any orientation mechanism is going to add weight in an unpleasant location from a vehicle handling perspective and/or be difficult to operate (e.g. having a manually-operated hinged arrangement on your roof wouldn't add much weight but you'd have to climb a ladder to align the panels). It's also going to have to withstand wind strengths of up to 180km/h or more while travelling.

I doubt anyone sells such things off the shelf so you'd likely be in bespoke territory.

iana · Guru

Moblet, what are you doing hovering over the keyboard waiting for my reply. But yes I have got you thinking. The best reply yet.
As for money to throw at it, am I not doing this anyway, its a question of whether the money is well spent.
As far as tracking or tilt systems, I haven't really considered this in depth yet.
Re panels in the shade, I read that panels that are over heated loose their efficiency pretty quick. In the summertime having the panels in the shade maybe a good thing.
Any "orientation mechanism is going to add weight", now I haven't mentioned any mechanical means, but it is not off the cards.

If I was formulating an idea it is this, I noticed that the solar panel attach legs appear to be glued in place. What if one mounted (glued) slotted tracks along the roof (Rino etc), then with click in fasteners, one could quickly set up solar panels, TV dishes etc, on any position on the roof, to get the optimal efficiency from all.
It is not an over the top solution, but could allow the panels to lay flat in the summer or when traveling, and in the winter, they could be angled up to maximise sun hours.
The satellite dish could be positioned to get the best reception and in all the risk of theft is reduced.

This is just formulating an idea or asking "Why" nothing is set yet. The way it is now may be the best path to take, I am just exploring.

-- Edited by iana on Wednesday 31st of December 2014 05:57:49 PM

Delta18 · Guru

iana wrote:

If I was formulating an idea it is this, I noticed that the solar panel attach legs appear to be glued in place. What if one mounted (glued) slotted tracks along the roof (Rino etc), then with click in fasteners, one could quickly set up solar panels, TV dishes etc, on any position on the roof, to get the optimal efficiency from all.
It is not an over the top solution, but could allow the panels to lay flat in the summer or when traveling, and in the winter, they could be angled up to maximise sun hours.
The satellite dish could be positioned to get the best reception and in all the risk of theft is reduced.

This is just formulating an idea or asking "Why" nothing is set yet. The way it is now may be the best path to take, I am just exploring.

-- Edited by iana on Wednesday 31st of December 2014 05:57:49 PM

A friend of mine has done just this on his poptop van, a couple transverse bars are mounted across the van, the front of the panels are hinged to the front bar and the rears are locked down with a clamp arrangement. Doesn't need to be too flash as forward motion tends to hold them down anyway.

When he sets up for more than a few days he orients the van as close as he can facing to north then unclips the rear of panels and lifts that end to the angle he wants and locks them in place there. Done in a few minutes.

Not sure what you mean by "The satellite dish could be positioned to get the best reception" as there IS only one position that a dish will get reception. Assuming you won't want to climb onto the roof to line up the dish you would have an automatic system that will find the satellite itself.

Cheers Neil

moblet · Senior Member

I ain't no helicopter, you must be talking to the hat

Not sure what you mean by solar panel attach legs being glued in place. If you're referring to the portable panels, the legs are typically bolted to the frame and fold in for transport and out for use. Most camping equipment and Jaycar stores would have portable panels on display.

Solar panels are now inexpensive enough that it'll almost certainly be more economical to buy excess capacity and install it flat on the roof like everyone else than to invest in fancy mounting arrangements. Your slotted track idea still sounds like it's going to have you climbing on the roof.

If you mount your panels clear of the roof they will run cooler and also provide shade cooling, but mounting them will be heavier and more expensive because of the aerodynamic forces they will have to survive while travelling.

iana · Guru

moblet wrote:
I ain't no helicopter, you must be talking to the hat
Not sure what you mean by solar panel attach legs being glued in place. If you're referring to the portable panels, the legs are typically bolted to the frame and fold in for transport and out for use. Most camping equipment and Jaycar stores would have portable panels on display.
Solar panels are now inexpensive enough that it'll almost certainly be more economical to buy excess capacity and install it flat on the roof like everyone else than to invest in fancy mounting arrangements. Your slotted track idea still sounds like it's going to have you climbing on the roof.
If you mount your panels clear of the roof they will run cooler and also provide shade cooling, but mounting them will be heavier and more expensive because of the aerodynamic forces they will have to survive while travelling.

Sorry didn't explain myself properly. The van I climbed up to view the roof appeared to have the attachments of the solar panels glued to the roof, as apposed to putting holes in it.

iana · Guru

Delta18 wrote:
iana wrote:

If I was formulating an idea it is this, I noticed that the solar panel attach legs appear to be glued in place. What if one mounted (glued) slotted tracks along the roof (Rino etc), then with click in fasteners, one could quickly set up solar panels, TV dishes etc, on any position on the roof, to get the optimal efficiency from all.
It is not an over the top solution, but could allow the panels to lay flat in the summer or when traveling, and in the winter, they could be angled up to maximise sun hours.
The satellite dish could be positioned to get the best reception and in all the risk of theft is reduced.

This is just formulating an idea or asking "Why" nothing is set yet. The way it is now may be the best path to take, I am just exploring.

-- Edited by iana on Wednesday 31st of December 2014 05:57:49 PM
A friend of mine has done just this on his poptop van, a couple transverse bars are mounted across the van, the front of the panels are hinged to the front bar and the rears are locked down with a clamp arrangement. Doesn't need to be too flash as forward motion tends to hold them down anyway.
When he sets up for more than a few days he orients the van as close as he can facing to north then unclips the rear of panels and lifts that end to the angle he wants and locks them in place there. Done in a few minutes.
Not sure what you mean by "The satellite dish could be positioned to get the best reception" as there IS only one position that a dish will get reception. Assuming you won't want to climb onto the roof to line up the dish you would have an automatic system that will find the satellite itself.
Cheers Neil

So it can be done simply, any tilt from the horizontal in the winter time would give an increase in efficiency.

What I meant about the dish was, from what I read into it, any tree, leaf etc. containing water/juice will stop reception. So one could move the dish to an area on the roof of the van that gives a clear view to the satellite.

PeterD · Guru

iana wrote:
Snip . . . do they work in the winter months when the sun is low on the horizon. In the summer when the sun is high above and you're camped out in the open yes all would be good, but is there another story?

The flat mounted panels do not work very well in Tasmania in winter. However properly angled panels also do not put out much total power, there is not enough sun down there in winter. On the other hand who wants to be down there in winter. The switched on campers follow the sun. You will find them north of the tropic when sun hours are at their least. You too can travel likewise and this will result in less difference in the sun hour difference as you travel.

Delta18 · Guru

iana wrote:

So it can be done simply, any tilt from the horizontal in the winter time would give an increase in efficiency. Look at any home that has solar panels, they are mounted on a north facing pitched roof, never flat, I wonder why.
What I meant about the dish was, from what I read into it, any tree, leaf etc. containing water/juice will stop reception. So one could move the dish to an area on the roof of the van that gives a clear view to the satellite.

You will find it is much easier to use a tripod on the ground than get on the roof to try to find a clear shot to the satellite.

iana · Guru

Thankyou all so far, all very constructive comments. I have however a couple more questions on the subject.

1/ Some of you mention charging up the batteries via solar when on the move. Now the camper trailer I had, had a deep cycle battery that was charged by the vehicle when on the move. Now those of you that have solar panels, does the vehicle also charge the caravans batteries when on the move, and if so, how do you know what work the solar panels are doing in this case.

2/ Again when at a powered site, the in house batteries were charged via the sites mains, again those of you that have solar panels is this also the case with you.

So if that is the case, the only time that you will know how the panels really work is at an un-powered site.

Santa · Guru

Check the battery charge after a couple of days stationary with no power consumption, you will find your batteries fully charged.

Trust me, they do work very well. wink

aussie_paul · Guru

When we getting ready to try some free camping we ran some tests in a caravan park. I would unplug the mains power to see how the 120 watt solar on the van roof charging a 100 amp hr in house battery. That gave me some idea of how the system worked and had the c/park power if needed. I did the same with the water to check shower flow etc.

To have a bit up our sleeves I ended up putting a second 100 amp house battery, and have a 120 watt foldable portable solar panel if needed.

Aussie Paul. smile

-- Edited by aussie_paul on Thursday 1st of January 2015 02:35:37 PM