Three years with a solar panel

[Guest 1footinthegrave]

This is the first time I've read this thread, and having just last week fitted a 90 panel to my van now becomes relevant. I notice in the original post the comment " more cost effective to fit an additional battery " but theres the conundrum, an extra battery still needs to be charged, as we almost exclusively use Aires up until now a fair bit of driving has been involved in achieving that, together with minimising battery usage, LED lights, low wattage 12 volt tv, etc.

Perhaps the efficiency of the panels now have improved since the original post wwe will see, but my take is even if the solar panel does not give much extra charging capacity, at least it will be exactly that, extra. The new panel I have just fitted shows my batteries for the first time being maintained at a float voltage of 13.7 volts to 13.8 volts.

 

All in all though an interesting read, so many thanks for the original post.

 

;-)

[BGD]

spospe - 2011-01-05 12:12 AM

 

Thanks dipsticks, the photo was a nice touch.

 

I am not 100% sure, but your roof does look a little different to ours and that probably explains how you managed to get an 85-watt panel on it.

 

I am jealous ;-)

 

 

 

Remember that surely you CAN have a solar panel that goes right over the top of a rooflight on such a vehicle.....so long as you fit long enough panel fixing legs to allow the rooflight to at least partially open (assuming you want it to remain open-able), and you are prepared for there to be a lot less light coming in through that rooflight.

A compromise, but perfectly possible.

 

[pepe63xnotuse]

BGD - 2013-08-05 2:10 PM

 

spospe - 2011-01-05 12:12 AM

 

Thanks dipsticks, the photo was a nice touch.

 

I am not 100% sure, but your roof does look a little different to ours and that probably explains how you managed to get an 85-watt panel on it.

 

I am jealous ;-)

 

 

Remember that surely you CAN have a solar panel that goes right over the top of a rooflight on such a vehicle.....so long as you fit long enough panel fixing legs to allow the rooflight to at least partially open (assuming you want it to remain open-able), and you are prepared for there to be a lot less light coming in through that rooflight.

A compromise, but perfectly possible.

 

That's good point...and on something like Transit,I would've thought that using a tidy pair of ladder rack/roof bars would be as easy (and as secure!)a way of doing it, as you're going to get.. ;-)

[spospe]

I never considered mounting the panel over the toilet roof light, but this is certainly possible and it would enable a much larger item to be installed. The panel might look a bit 'odd' when viewed from the road, but at least the position would mean that it would be free from shadows cast by other roof furniture.

 

Panels do provide 'extra' power (saved us once when a battery failed when we were away), just don't expect too much on a dull winter's day.

 

I hope that this post does not get duplicated, because I just posted it and then it vanished. I have noticed that the Forum is getting very slow at times and this can cause strange problems.

 

 

[colin]

spospe - 2013-08-05 12:28 PM

 

Has no one any comments to add?

 

I really thought that there might be some interesting personal experiences to be shared on this subject and that we could all learn a bit.

 

Are you all on holiday?

 

When I check back I see we've been using solar panels for over 14 years on vans(slight mistake on my earlier post). AFAIC it is a fit and forget option, we now have a 85w panel and during winter it kept the leisure battery at a safe level even though the van is stored under a 'car port', in summer we can if wanted go indefinatly with out any other form of top up, something an extra battry can never achieve, so we only have one battery and have no need at all of a second battery

[dipsticks]

I removed the omni-directional aerial that was never used and fitted a 40 watt panel thus totalling 125 watts which is ample in our case for year round use. I would not wish to install a panel over a roof light for a multitude of reasons not least cleaning and maintenance.

Michael has well covered most valid points, I can only re-iterate the need to keep a check on electrolyte levels in flooded batteries and beware of the higher voltage associated with 100% charging, up to 15v, which may be damaging to some sensitive electronic equipment. Make sure that flooded batteries are vented outside the vehicle and living area.

I fitted a Morningstar MPPT controller which seems to give far superior results to the old PWM controller but is somewhat more expensive than the Morningstar Sunsaver. The only other tip I can offer, when using flooded cell batteries with solar charging, is to fit a switch across the bridging terminals (if fitted) on the regulator so the peak voltage can be reduced when the vehicle is laid up. This will reduce gassing and extend the topping up period.

[BB]

I have just found this very informative thread. I have been toying with the idea of adding a solar panel to our 2006 Transit-based Duetto. Having only had the van for 6 months, and being fairly low power users (no TV, LED lights) I have only been thinking of out-of-season battery conditioning (as we have to park away from our home, with no 240v supply available).

 

I'm thinking of a free-standing low-output panel which I can leave loose on the van roof over-winter, angled towards what little sun we get here, connected to main and leisure batteries via a couple of pairs of 4mm banana plug sockets.

 

When the van is in use in the summer, the same panel can travel in the van until we park-up, and then be sat on floor / roof / dashboard - whichever gives best view of sun.

 

I am now also investigating wind generators, but feel that this may be more intrusive if parked in a less than isolated position.

 

[colin]

Subsequent to my earlier posts on this thread we have extended the roof on our van shed to cover a second van, this has meant the solar panel cannot cope with keeping vehicle battery (as well as leisure) topped up, also the vehicle battery has never been the same since the winter we had up to -16c and struggles to keep charge.

Last year I purchased a 'cheap' 40w panel and reg, when parked up at home I hook this up to vehicle battery, this keeps the battery charged, but think I will need a new battery sooner rather than later.

[StuartO]

I've had about five years with 130 watts of panel and two Exide G80 gel leisure batteries and, without ever keeping records to monitor performance, it seems to have been a "fit and forget" good system.  We are light users of 12v so the panels would usually fully re-charge the batteries during the day in summer, so an EHU became unnecessary.

 

Before the panels I was always disappointed by how little charge we got out of a day's driving.  Our MH has a modern alternator but it takes time to recharge a battery and so even six hours of driving wouldn't do more than half re-charge them.  With solar panels (which work just as well driving as when parked up, we get a full recharge by the end of a summer day anyway.

 

This year we replaced our twin Exide G80s (on age) with a single new one, thinking that we didn't really need two (so save the weight) which practice has shown that we don't.

 

In winter, at our new home, the MH lives outdoors alongside the house and the solar panels certainly keep our single leisure battery fully charged - so I don't bother plugging in to the mains.

 

I'm a big fan of solar panels and 130 watts seems to have been enough for us.

 

[aka4ajax]

I jumped in on the Solar Panel game back in May this year, having read this post and many many more of similar quality, especially http://www.aandncaravanservices.co.uk/stock-list.php site.

I took all the advice and boy am I pleased with the results.

I bought 2 x 100w semi-flexible back-cell mono what ever you call them, the newest design, expensive but happy now.

I ran them all on the recommended snap connectors and supplied cabling, again the cable was expensive for a bit of wire, but i read if you use cheap wire you get a voltage drop.

I installed in line fuses and the regulator recommended for my electroblok unit. That too was twice the price of the ebay specials.

connected that all up to 2 x110Amp/hr new habitation batteries and went off for a week holiday in the lakes.

That went well, but i still had a day between when I was on hookup and the batteries were topped up every other day as we moved around a bit.

But this latest epic adventure in France has tested the set up to the max. We have 2 x tv's laptops 4 mobile phones and are very heavy electric users, teenage kids see, well thats my excuse.

we spent 15 glorious days and 14 nights on the continent without once requiring hook up, there was no electric rationing by me acting as the electric police and there was never a worry if the van would not start.

So thanks for all the advice, took it all onboard and its worked out great. 

Neil

[tonyishuk]

Just wondering why a small shadow, or something such as a small amount of leaves has a fairly dramatic effect on output ?

 

As this the case, I would have thought the problem would have been overcome in later generation of panel design.

 

Does This sort of problem occur with domestic panels on house, if they are not regularly cleaned ?

 

I have often thought of fitting a panel, but in a hot climate, prefer shade rather than siting the m/home in a sunny spot to catch the rays for the panel.

 

Rgds

 

 

[aka4ajax]

Individual solar panel cells are very sensitive and do not like being constantly switched on and off. When some cells in the panel are not working the other cells work harder to try to compensate. As a result the solar cells that are not in shade have a tendency to overheat and burn out.

This website explained it for me: http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

[colin]

After a thread on another forum i've conducted some experiments, I've struggled a bit to get conclusive results as my system is not set up for detailed monitoring (and I have a life), but my efforts so far have shown that (on my system at least) shadowing does not have as dramatic effect as some might tell you.

Some have found that completely blocking a cell (such as when leaves are on the panel) might knock a fair bit off the power, but in the case of my panel this doesn't happen anywhere near as bad, if you are in the shade of tall trees with an otherwise open sky the panel will still produce power but it will be down, in dappled shade in autumn when the leaves have dropped the panel will still produce some power, but if you are under low branches which produce 100% shade you may well not get any output from panel.

So as you can see a definitive answer is hard to give, but most who have tried panels seem happy with them, we've used them for something like 18years on vans and it's worked for us and I don't ever see us having a van without solar.

 

[StuartO]

aka4ajax - 2016-08-22 5:30 PM

Individual solar panel cells are very sensitive and do not like being constantly switched on and off. When some cells in the panel are not working the other cells work harder to try to compensate. As a result the solar cells that are not in shade have a tendency to overheat and burn out.

This website explained it for me: http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

 

I couldn't make much sense of the website to which you provided a link but I did have a conversation with a solar panel dealer/expert a while ago and he explained the importance of installing diodes between panels during installation, to minimise the impact of shading.  Even partial shading of a panel reduces its output markedly because shaded cells add to the resistance of the circuit as well as stop generating voltage themselves. (Cells in the same panel must be connected in series rather than in parallel.)  Diodes between panels somehow help to prevent contagion of the impact on to the next panel, even though I understand the next panel is in series too.

 

My schoolboy physics couldn't follow the precise nature of this phenomenon either but I got the bit about the importance of diodes between panels, which some installers don't bother with.

 

[aka4ajax]

The website I found easy enough to follow. Plus it mentions the use of by-pass diodes.

[veletron]

Here's my stats, straight from the control panel

 

http://photos.veletron.com/index.php/album151/Van-Mods/14718983899440

 

MPPT regulator, operational since June last year. 1x120watt and 2x40Watt panels wired in parallel. 2x140AH batteries.

 

Nigel

 

 

[aka4ajax]

That's a cool monitor, where do I get one and how much please ??

[aka4ajax]

That's a cool monitor, where do I get one and how much please ??

[colin]

StuartO - 2016-08-22 9:00 PM

aka4ajax - 2016-08-22 5:30 PM

Individual solar panel cells are very sensitive and do not like being constantly switched on and off. When some cells in the panel are not working the other cells work harder to try to compensate. As a result the solar cells that are not in shade have a tendency to overheat and burn out.

This website explained it for me: http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

 

I couldn't make much sense of the website to which you provided a link but I did have a conversation with a solar panel dealer/expert a while ago and he explained the importance of installing diodes between panels during installation, to minimise the impact of shading.  Even partial shading of a panel reduces its output markedly because shaded cells add to the resistance of the circuit as well as stop generating voltage themselves. (Cells in the same panel must be connected in series rather than in parallel.)  Diodes between panels somehow help to prevent contagion of the impact on to the next panel, even though I understand the next panel is in series too.

 

My schoolboy physics couldn't follow the precise nature of this phenomenon either but I got the bit about the importance of diodes between panels, which some installers don't bother with.

Read my post and you will see that on my panel partial shading does not dramatically reduce the output in most circumstances, I can get it to do that but it requires me to completely obscure around 25% of panel such that no light at all hits that area, this is most unlikely to happen in a real life situation, being next to a hedge or tree that casts a shadow across the panel still gives an output in proportion to the shade, this is because such a shadow still allows light to hit the panel, abet not as strong.

[aandncaravan]

tonyishuk - 2016-08-22 5:18 PM

 

Just wondering why a small shadow, or something such as a small amount of leaves has a fairly dramatic effect on output ?

 

As this the case, I would have thought the problem would have been overcome in later generation of panel design.

 

Does This sort of problem occur with domestic panels on house, if they are not regularly cleaned ?

 

I have often thought of fitting a panel, but in a hot climate, prefer shade rather than siting the m/home in a sunny spot to catch the rays for the panel.

 

Rgds

 

 

Most Solar Panels are made up of multiple square 'cells' soldered to adjoining 'cells', hence all the silver tracks you see on a big panel 'wiring' all the cells together.

 

When a Solar panel is in bright Sun and a very small part, like the size of a leaf covers a 'Cell', that cell in shade starts to draw power from the surrounding cells and becomes a heating element.

 

This results in maybe 4 or 5 'cells' not contributing to the overall output, even though the Leaf might have covered only a tenth of one 'cell'.

 

 

If something like a Stereo Radio Aerial, just 1mm wide and 40mm long, casts a 'thin long' shadow it can impact many more 'cells' that then become 'heaters' so dropping the power dramatically.

In this case 12 'cells' might be effected so the impact on the output will be proportional to the number of cells.

Even though the actual shadow may be less than 2% of the panel, if 30% of the 'cells' have a tiny shadow on them the output can drop by more than 30%.

The lower the sun gets in the sky the 'longer' the Aerial shadow might become, so impacting more cells. So the effect is 'exaggerated' at the end/start of a day, as noted above.

 

If the same 'cells' get the same shadow passed over them day after day, there can be localised deterioration of the 'cells', and even failure.

Hence our Solar Hints and Tips page emphasising the importance of a Solar Panels location so there are no shadows at all : http://www.aandncaravanservices.co.uk/solar-power.php

 

 

How much an individual Panel is affected will depend on its build. Some Panels have 'blocking diodes' built-in between every single square 'cell' to prevent this reverse flow of electricity. Some every other 'cell', some between each row.

The budgets may have no blocking diodes at all, hence the advice from Stuart to use additional externally added blocking diodes if you link two Solar panels together.

 

But it's a trade off, as each blocking diode does reduce the efficiency of a Solar Panel, the more blocking diodes there are, the lower the overall output.

Hence the strange anomaly of some 'budget' panels actually producing more real power in bright sun than a Bosch Panel, but the budget panel may be considerably lower output if even a Spider sized shadow is present.

 

I would guess that the older panels of the OP are low in blocking diodes, hence the comparatively high figures in good sun than might be expected from a modern Solar panel.

 

 

 

 

 

[StuartO]

colin - 2016-08-22 10:06 PM

StuartO - 2016-08-22 9:00 PM

aka4ajax - 2016-08-22 5:30 PM

Individual solar panel cells are very sensitive and do not like being constantly switched on and off. When some cells in the panel are not working the other cells work harder to try to compensate. As a result the solar cells that are not in shade have a tendency to overheat and burn out.

This website explained it for me: http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

 

I couldn't make much sense of the website to which you provided a link but I did have a conversation with a solar panel dealer/expert a while ago and he explained the importance of installing diodes between panels during installation, to minimise the impact of shading.  Even partial shading of a panel reduces its output markedly because shaded cells add to the resistance of the circuit as well as stop generating voltage themselves. (Cells in the same panel must be connected in series rather than in parallel.)  Diodes between panels somehow help to prevent contagion of the impact on to the next panel, even though I understand the next panel is in series too.

 

My schoolboy physics couldn't follow the precise nature of this phenomenon either but I got the bit about the importance of diodes between panels, which some installers don't bother with.

Read my post and you will see that on my panel partial shading does not dramatically reduce the output in most circumstances, I can get it to do that but it requires me to completely obscure around 25% of panel such that no light at all hits that area, this is most unlikely to happen in a real life situation, being next to a hedge or tree that casts a shadow across the panel still gives an output in proportion to the shade, this is because such a shadow still allows light to hit the panel, abet not as strong.

 

I think realisation is dawning, that shaded cells stop generating voltage and become resistive loads in the circuit, so assuming they are connected to other cells in the panel in series, they will actively reduce the panel output, rather than just stop contributing.  Alternatively, if cells are connected in parallel, the shaded cells will still reduce output because they will short across generating cells by presenting a resistive load.  Ideally I suppose all the cells on a panel would be connected in parallel and there would be a diode in series with each cell, so shading would have no effect.  But that would limit the output voltage of the panel to that of a single cell.

 

I might be talking complete rubbish here!

 

[colin]

aandncaravan - 2016-08-22 11:20 PM

 

If something like a Stereo Radio Aerial, just 1mm wide and 40mm long, casts a 'thin long' shadow it can impact many more 'cells' that then become 'heaters' so dropping the power dramatically.

In this case 12 'cells' might be effected so the impact on the output will be proportional to the number of cells.

Even though the actual shadow may be less than 2% of the panel, if 30% of the 'cells' have a tiny shadow on them the output can drop by more than 30%.

The lower the sun gets in the sky the 'longer' the Aerial shadow might become, so impacting more cells. So the effect is 'exaggerated' at the end/start of a day, as noted above.

 

 

And this was why I started doing experiments, I found this to be wrong.

[colin]

StuartO - 2016-08-23 8:37 AM

 

I think realisation is dawning, that shaded cells stop generating voltage and become resistive loads in the circuit, so assuming they are connected to other cells in the panel in series, they will actively reduce the panel output, rather than just stop contributing.  Alternatively, if cells are connected in parallel, the shaded cells will still reduce output because they will short across generating cells by presenting a resistive load.  Ideally I suppose all the cells on a panel would be connected in parallel and there would be a diode in series with each cell, so shading would have no effect.  But that would limit the output voltage of the panel to that of a single cell.

 

I might be talking complete rubbish here!

Some people have taken a well known 'problem' ,total blocking of light to a cell, and assumed a shadow will do the same, my experiments have found this is not true, at least not on my panel.Consider this, you can 100% shadow a panel by parking near a building and if it's a bright sunny day it will still produce some power, but if you have a panel with all the cells connected in series with no bypass diodes, completely block the light to one cell with say a large leaf and it may be that you get no power at all.

[veletron]

aka4ajax - 2016-08-22 9:54 PM

 

That's a cool monitor, where do I get one and how much please ??

 

Its a part of EP Solar's range of kit. MT50 is the name of the display panel (about £50) while the controller is the 20A 'EPsolar Tracer 2215B' (which was about £100). The 10A version 'Tracer 1215B' is cheaper. Not cheap, but I dont chop and change vans all the time so worth it. There is also a USB cable which allows the same stats to be viewed on a PC/Phone. They work as a pair communicating via CAT5 network cable.

 

But... this ebay auction has both for £95 - bargain! From China though so usual delays and possible import duties!

 

http://www.ebay.co.uk/itm/EPsolar-Tracer-2215BN-MPPT-Solar-Charge-Controller-Regulator-20A-Remote-MT-50/201367763949?_trksid=p2141725.c100338.m3726&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D20150313114020%26meid%3D9f0546c765474a3ca4a81280b8894881%26pid%3D100338%26rk%3D1%26rkt%3D14%26sd%3D152203849977

 

Nigel

[aandncaravan]

StuartO - 2016-08-23 8:37 AM

colin - 2016-08-22 10:06 PM

StuartO - 2016-08-22 9:00 PM

aka4ajax - 2016-08-22 5:30 PM

Individual solar panel cells are very sensitive and do not like being constantly switched on and off. When some cells in the panel are not working the other cells work harder to try to compensate. As a result the solar cells that are not in shade have a tendency to overheat and burn out.

This website explained it for me: http://www.solarchoice.net.au/blog/partial-shading-is-bad-for-solar-panels-power-systems/

 

I couldn't make much sense of the website to which you provided a link but I did have a conversation with a solar panel dealer/expert a while ago and he explained the importance of installing diodes between panels during installation, to minimise the impact of shading.  Even partial shading of a panel reduces its output markedly because shaded cells add to the resistance of the circuit as well as stop generating voltage themselves. (Cells in the same panel must be connected in series rather than in parallel.)  Diodes between panels somehow help to prevent contagion of the impact on to the next panel, even though I understand the next panel is in series too.

 

My schoolboy physics couldn't follow the precise nature of this phenomenon either but I got the bit about the importance of diodes between panels, which some installers don't bother with.

Read my post and you will see that on my panel partial shading does not dramatically reduce the output in most circumstances, I can get it to do that but it requires me to completely obscure around 25% of panel such that no light at all hits that area, this is most unlikely to happen in a real life situation, being next to a hedge or tree that casts a shadow across the panel still gives an output in proportion to the shade, this is because such a shadow still allows light to hit the panel, abet not as strong.

 

I think realisation is dawning, that shaded cells stop generating voltage and become resistive loads in the circuit, so assuming they are connected to other cells in the panel in series, they will actively reduce the panel output, rather than just stop contributing.  Alternatively, if cells are connected in parallel, the shaded cells will still reduce output because they will short across generating cells by presenting a resistive load.  Ideally I suppose all the cells on a panel would be connected in parallel and there would be a diode in series with each cell, so shading would have no effect.  But that would limit the output voltage of the panel to that of a single cell.

 

I might be talking complete rubbish here!

Stuart, that is my understanding of it and put much better than my explanation.