Solar panels

[ianmayco68]

Hi all , I’m looking to fit some solar panels to the 110 and I’m after some advice . I’ve done a search but most of the posts are from a few years ago so thought I’d ask for some updated views . I’ve looked on 12volt planet but there kit , although nice and very good is too expensive for me at the minute so eBay specials are the order of the day I’m afraid . I have done some research and know that mono crystalline panels are the best and the mppt controllers are better for uk use , so I’m after some recommendations on kit brought off eBay or anywhere else that’s cheap😁 , also where have people found best to fit the panels , I will have a roof rack fitted ? Are fixed panels or removable ones best ? And how have people got the cables up to the roof ? That’s all I can think of for now .

cheers Ian 

[FridgeFreezer]

Rule 1 is all the figures are lies.

Rule 2 is if you're moving around every day or every other day you may as well not have panels as your alternator will replenish more charge in 15 minutes driving than a solar panel will in an entire day. If you can fit a bigger alternator, do that.

Rule 3 is fit as much battery (Ah capacity) in as you can, in concert with Rule 2 this will give you the simplest and cheapest setup.

After that... work out how much power you need, multiply it by 10 and pick a panel/controller that does claims that.

Fancy panels and/or controllers are only going to give you marginal gains (maybe 10% in the real-world) over just buying the average-grade cheap stuff from China, and if your setup is that marginal you've got bigger issues. Also, a lot of the fancy stuff is just the Chinese stuff with a different sticker on it anyway.

We run 2x 100W panels plus 2x cheapo MPPT controllers on the ambulance. Connected through the roof using an AMP sealed connector. We're limited on the battery size so added panels to compensate but it's not a great example of how to do it.

[ianmayco68]

Cheers Fridge , main reason for fitting is I intend to start carp fishing again next year as I’m spending to much time in the shed and not enough time enjoying myself and I’m not getting any younger , so could be parked up by a lake for 3days to a week with a fridge running so was thinking it would be a good idea fitting some to keep the batteries topped up . I’ve worked out how that sterling pro r  latching relay works , I think , so will be fitting that in conjunction with the solar panels as a bit of a fail safe that’s why I didn’t really want to spend a fortune .

[Bowie69]

If you are parked up, get a blanket or portable panel, and a long extension so you can park where you want, as well as put the panel in the best position, this stops you hindering the charge by leaf cover or sun position, just because you want to park in a nice/sheltered spot. 

[Sigi_H]

It's better to park in the shadow and have portable modules in the sun. Keep in mind, that a MPPT works best if two 12V Panels are connected in series, since a MPPT is a stepdown converter. 2 panels in series are easy to manage with something like that

portable modules can easily be adjusted to the sun in order to get more energy

[ianmayco68]

Cheers all , hadn’t considered portable panels .

[FridgeFreezer]

14 minutes ago, Sigi_H said:

Keep in mind, that a MPPT works best if two 12V Panels are connected in series, since a MPPT is a stepdown converter. 2 panels in series are easy to manage with something like that

Sorry, wrong.

MPPT means "Mean Power Point Tracking" which just means the controller adjusts the load on the panel to achieve best power output (volts x amps). The more simple controllers, often (inaccurately) called PWM just regulate the voltage to the battery to avoid over-charging it.

Most controllers (MPPT or not) are step-down, in that if the panel voltage falls below 12v (or your battery voltage plus a bit) they aren't charging anymore. Adding the circuitry to boost the voltage adds cost and is why you'll almost never see it in solar stuff as it's far easier to start with panels which have an "open circuit" voltage of 18v or more.

[Snagger]

Definitely go portable - it allows you to incline and rotate the panels to face directly at the sun, which makes a huge difference, and to park the car in the shade while having the panels in the sun (huge benefit in warm climates).  It also means the panels don’t take up valuable rack space and aren’t exposed to the elements when not needed.

The whole mono/poly crystal and PWM/MPPT debate is interesting, and there are theoretical clear benefits to monocrystal with MPPT, and one assumes that the high cost panels are better, but I have watched a few videos that blow that out of the water.  One live-filmed trial using the same wiring and location saw the cheap panels with PWM beat the output of an identically rated panel several times dearer with an expensive MPPT controller.  The pattern I have noticed, and it may be misleading, is that price of panel is irrelevant but having a matt finish rather than glossy ems to significantly increase panel output.  None of the videos mentioned that factor, and the cheap panels tend to be the matt ones, but I think they simply reflect less of the sunlight and have higher absorption, especially if they have a very thing transparent coating which will absorb less light.

But the folding blankets seem the most practical solution - you can lay them out, hang them vertically, use them sloped as an awning, all orientated to the sun, and they are less likely to get damaged or stolen.

This is a good video: 

 

[Sigi_H]

12 hours ago, FridgeFreezer said:

Most controllers (MPPT or not) are step-down

You say what I mean. Almost all. They normally have input voltages of around 36 V and step down to ca 13.8 V Battery level, which means (36V)  2 x open voltage, 2 panels in series. Efficiency rises a lot then. Where parallel setup breaks down, because generated voltage is to low, serial is still charging.

Efficiency will rise a lot, when the panels stay "cool". That is also better with portable ones, which are placed to get cooled from the back side.

I am able to store my panels easily in the car. In my last vacation I needed them once in ca 5 weeks. On the roof I only have 30 W to keep the battery alive, when the car parks for longer time at home.

Edited November 16, 2019 by Sigi_H

[miketomcat]

I have the same panel and controller as fridge but only one. The controller is mounted in the car connected to one of my 110 ah varta AGM batterys. The other identical battery is connected to the engine and 90 amp Mondeo alternator. Between the two I have a voltage sensing relay (adjusted lr rear window item) that runs a solenoid. My winch, fridge (waceo cf25) etc run off the second battery so if it goes flat I can still start. My panel is connected to the car via a plug mounted on the back so I can place the panel in the sun. The only problem is storing the panel while moving from site to site. My system worked well in Scotland and kept the fridge running for 3 days without moving the car no problem.

Mike

[Sigi_H]

coment to the video

A friend of mine is working in solar business. He told me, electrical power does not say everything about quality. It is important, that panels are built perfectly in mechanical shape. Often people come to them, having cheap panels on the roof ... with drastically reduced el. power or mechanically damaged.

[Eightpot]

I use a cheapy 80w panel, running through a cheap 20 quid solar controler off eBay to charge a second 110ah battery.   It's on my African 110, more sun (though shorter hours) but more heat also, and that will keep my fridge going easily for 4 days without moving and without dropping battery voltage too low, but with beer temp set to icy cold.  

If I'm roof mounting a panel I attach it to a couple of hinges on one side so I can prop it up to follow the angle of the sun which does help. For your purposes a portable panel might well be a nicer fix, and less weight to drag about every day. 

On my old expedition rangie, I bought an equally cheapo 40w panel and ebay solar controller over ten years ago - the car has been laid up for a couple of years waiting for some tlc, but its second battery is still tip top, controller all lit up and panel pumping volts through.   Happy enough with the cheap kit, certainly wouldn't pay out for more efficiency as I don't pay anything for the daylight in the first place 🙂

 

[Snagger]

6 hours ago, Sigi_H said:

coment to the video

A friend of mine is working in solar business. He told me, electrical power does not say everything about quality. It is important, that panels are built perfectly in mechanical shape. Often people come to them, having cheap panels on the roof ... with drastically reduced el. power or mechanically damaged.

Cheap vs expensive doesn’t matter.  It’s their condition.  Damaged expensive panels will perform worse than cheap clean ones.  The installation is also more important than price, using correct grade wiring and being installed out of shadows, with correct orientation in all axis.

[ianmayco68]

Thank you all very much for the input , very interesting video Nick looks like it's a good job I can only afford the cheapy one's  . The write up's I'd read said monocrystalline panels are better because it's one crystal as apposed to lots of crystals in polycrystaline one's ( ie has gaps between the individual crystals ) and both controllers are good but the MPPT one's are better in weather like we get in the UK , but from the comments above it looks like 100w panels are adequate then up to 200w is more than enough . I definitely like the idea of portable fit when static then store safely when moving , could rig something up in the roof to store them .

[Snagger]

Definitely better to have two cheap panels and a PWM controller than one expensive panel and MPPT.  That lad did a video comparing MPPT to PWM and the outputs were very similar, the PWM more often being a little higher than the MPPT.

[Sigi_H]

A cheap panel with high el. power makes no sense, when it sucks water under the transparent top layer and corrodes internally. It will be destroyed soon. But everybody has to decide and nobody can see on ebay whether they are built solidly

 

[Snagger]

Sigi, the point is that the panels come from the same factories in China - the price difference is profit margin for the wholesalers and retailers.  It does not compare to vehicle mechanical parts, where there are wide variations in quality of materials and machining.  Domestic panels are a different matter, where they take a beating from storms and sub-zero conditions, but there will be no discernible difference in ruggedness between different suppliers of vehicle panels if you compare rigid with rigid, flexible with flexible.  There are plenty of RV and “van life” videos corroborating this and the video I linked above.  Furthermore, if you can buy three cheap panels for the price of one Gucci panel, then the chances of having at least one work after several years is three times higher.  Don’t underestimate the value of component or system redundancy.

[Sigi_H]

@snagger

yes, you are right. One never knows. But keep in mind, that even chinese factories are producing A, B and C Parts. Not all of them have the same quality but look the same.

[FridgeFreezer]

Our cheap-ish 100W panels came from Alpha Batteries on eBay and are Bosch branded (on the silicon, not just a sticker).

From trying to chip the glass off of one that got broken in transit (to see if I could replace the glass) I can tell you they are bonded together incredibly well, the whole surface area is bonded to the glass incredibly strongly and there was no way to get it off even when the glass had been shattered (courier dropped it on its corner!) - this is the panel miketomcat now has and even with shattered glass it's working fine.

[Snagger]

12 hours ago, Sigi_H said:

@snagger

yes, you are right. One never knows. But keep in mind, that even chinese factories are producing A, B and C Parts. Not all of them have the same quality but look the same.

Yep, but the A* or B (light cosmetic seconds) and you’ll avoid the A prices without any performance degradation.  Buy the C and who knows what you’ll get?  They’ll work, but a Gucci C will be a fraction as powerful as a cheap B.

[Sigi_H]

Everyone has to decide himself and of course, I did not see your panels.

I just report my friends experiences and he has a lot.

[Snagger]

9 minutes ago, Sigi_H said:

Everyone has to decide himself and of course, I did not see your panels.

I just report my friends experiences and he has a lot.

I haven’t bought them as my car is in storage and I’m spending years working overseas.  But I have been doing a lot of reading up and watching videos, as well as quizzing the local overlanders about numerous issues I have plans for, and this is one of them.  In the absence of being able to do the actual work, I have been doing an abundance of research and planning to fill the void.

[Peaklander]

Ian, here's our experience. We have a 100W rigid panel that is mounted between a couple of roof bars. It stays there until I remove it for the worst of the winter. We have two matched batteries under the passenger seat, one for the engine and the aux for a compressor fridge, Eberspacher and a few additional lights. A Ctek controller connects it all together and controls the panel.

This has been fitted for three years now and we no longer take a mains hook-up or backup charger since fitting the panel. We have experienced a fair spread of weather but not extreme winter - only frosty autumn nights. In summer on trips we have had 40+ C for several days and 30+C for several weeks. Also had weeks of cloud, rain and temperatures in teens of C. Mostly this weather has been in long day-times (May, June July) but also a bit in August / September / October.

I went rigid because it's more flexible than a flexible one 🙂, in that it can be removed easily. I didn't go portable because it's often windy and I don't want the hassle of trying to anchor a panel down but at an angle to the sun in the wind. Also in spite of the alternator running when we are moving, I prefer that the solar panel is still operating. Whenever you stop it's there, ready and working and there's no faffing about. Whether this is useful though, depends on the style of travel. 

The experiences? Well in hot climes the first thing I suggest is to have the facility to shade the interior by blanking the windows. We have home made blinds made of silver bubble wrap but with a layer of black binbag on the outside face where they press against the glass, to make for a bit of camouflage. The silver just makes them stand out too much when you don't want them to. Covering the fridge with a silver wrap is also useful. Of course parking in the shade helps but isn't always possible or desireable (in spite of what I just said).

The 100W panel seems to adequately power the battery (mostly the fridge) over an extended period but a week in one camp this summer, with temperatures never below 22 and maxing at high 30s and low 40s, found us fretting about the declining aux battery but it only went to about 11.5V before we eventually moved. This I think was with the panel not facing the sun at all (we have an elevating roof) but obviously still in a bright sky.

The biggest demand has been recently when parked for three days in bright sun but at the end of October, so very short days and nights at or below freezing. The heater and some demand from the fridge really pulled on the battery but still it maintained over 12V.

This most recent experience has got me thinking whether we have enough solar generating capacity or whether it's not enough battery storage capacity. The latter would require either a second aux battery (nowhere to put it) or the ability to cross connect the engine battery (dodgy in several ways, not least the chance to flatten it).

The only way to answer this is to get some real data. So I am looking at fitting some shunt type ammeters, or maybe hall effect ones that might be easier to install, to try to measure the panel output or possibly the input to the battery and also the output side to see what's being drawn. The latter might be the same ammeter that just shows plus or minus as the power flows in or out. Needs more thought.

Ours aren't necessarily the same circumstances as you will have but I hope this helps.

Tim

Edited November 18, 2019 by Peaklander

[ianmayco68]

Cheers Tim , people’s experiences are more valuable than anything , you can read everything and anything about a subject but how that works out in the real world is always different. I’ve looked into the c-tek system but since I got that sterling relay for free thought I’d try that first, but c-tek do a battery sense device that sends data to your phone I believe and I don’t think it’s that expensive. The problem of space and where to fit stuff is puzzling me , I’ve got me starter and 2 aux batteries and the newly acquired Eberspächer to squeeze in but it will come to me eventually.
 Cheers Fridge found alpha batteries on eBay and they got some German panels at reasonable money just means I might have to buy the fittings myself , so I’ve noticed there’s different types of plugs for plugging the solar panels in which are best ? On the video Snagger put up the guy used Anderson connectors are they any good ? And I’ve found a few controllers with different features any Avon these would be most helpful, links below .

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F323913013492

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F202807395945

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F401767483272

few different ones there but middle one has the ability to connect 2 batteries , and a bit more expensive one just for good measure.

https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F302456110923

cheers Ian 

[Snagger]

Anderson sockets are very useful, and they do come in different sizes.  I don’t know how much difference they make to resistance in these applications over the plugs fitted by manufacturers - I think that guy did it to allow for flexibility in what he connects to his system, not just panels.  I have Anderson sockets for my main battery and jump leads, and it makes a much safer, more secure and quicker connection than their jaws at the other end.