Page 2 of 3 FirstFirst 123 LastLast
Results 21 to 40 of 58

Thread: How to select a good 12volt solar panel?

  1. #21
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by loanrangiel View Post
    They really only need to put out about 14v as the reg with reduce that to 13.7, amps is where the moneys at.

    Sent from my K10000 using Tapatalk
    Ah yes, but now you are understanding my point, the conversion factor!

    If a panel can produce 8.3 Amps at 19volts, then it should be producing a higher current at charge voltage levels.
    Or am i missing something here?
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!



  • #22
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,308
    Thanks
    833
    Thanked 1,498 Times in 657 Posts
    Rep Power
    711
    Reputation
    29047

    Default

    It ain't necessarily so.

    Solar Cell I-V Characteristic

    However, there is one particular combination of current and voltage for which the power reaches its maximum value, at Imp and Vmp. In other words, the point at which the cell generates maximum electrical power and this is shown at the top right area of the green rectangle. This is the “maximum power point” or MPP. Therefore the ideal operation of a photovoltaic cell (or panel) is defined to be at the maximum power point.



    Also, once the panel is exposed to direct sunlight and starts generating power the temperature coefficient kicks in:

    The effect of temperature on solar panel performance

    Temperature has an effect the efficiency and maximum pv output of a solar panel. The hotter a panel gets, the less power it generates. The ambient temperature, temperature coefficient of the actual panel and the type of installation are all factors that affect the yield potential of a solar power system.
    Last edited by Thala Dan; 18-05-19 at 07:57 AM.

  • The Following User Says Thank You to Thala Dan For This Useful Post:

    ol' boy (19-05-19)

  • #23
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Well I don't think much of the regulator outputs...

    15.59vdc on Calcium

    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #24
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Solar Blanket Direct output is 20.1vdc and the blanket would be 30degrees offset to the sun currently

    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #25
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Was very hard for me to get a current reading, as every battery I have is fully charged...

    But on the Landcruiser with 2 x N70ZZ Battery's in parallel and the accessories on and fridge running, I've managed to get 5 amps out of the panels through the horrible PWM solar controller.

    Shading one panel section dropped 0.5Amp
    Shading two panel sections dropped 1.2Amp

    Last edited by ol' boy; 19-05-19 at 01:52 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • The Following User Says Thank You to ol' boy For This Useful Post:

    william10 (18-05-19)

  • #26
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    So output is lousy
    Set up is fiddly and painful
    Takes up heaps of room on the ground
    And moving the panel/blanket around to follow the sun is a pain in the butt
    Being black panel in a black canvas sleeve heat soak was massive, the panels actually smell like hot electrical burning.
    (so hot, that i did not immediately fold the panels back up after use, i left them in the shade first to cool down)

    But pack up size, weight and transportability are brilliant
    You would leave the panel in your vehicle full time, same size and weight as a laptop in a bag.

    I'll test again with my DC-DC charger inbuilt MPPT charge controller and see if things improve
    Last edited by ol' boy; 19-05-19 at 01:54 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • The Following User Says Thank You to ol' boy For This Useful Post:

    william10 (18-05-19)

  • #27
    Senior Member

    Join Date
    May 2018
    Posts
    724
    Thanks
    179
    Thanked 757 Times in 348 Posts
    Rep Power
    334
    Reputation
    14714

    Default

    Quote Originally Posted by oceanboy View Post
    So output is lousy
    Set up is fiddly and painful
    Takes up heaps of room on the ground
    And moving the panel/blanket around to follow the sun is a pain in the butt
    Being black panel in a black canvas sleeve heat soak was massive, the panels actually smell like hot electrical.

    But packed up size and weight are brilliant.
    In other words they work best when they are not being used?
    Brilliant!!!

    If you have noticed the heat soak this time of year, Imagine what they would be like on a clear summers day. Things will be literally melting. Of course the hotter they get the greater the generation fall off and one just knows these things are going to fall right of the perch with the undoubtedly cheap cells they are using.

    I rather have something bigger and bulkier that performs a worthwhile function than something that's best feature is when it is packed away!
    I wonder if Bunnings are getting out of them because they had too many come back or realise they are simply not fit for the purpose they are sold for?

    You would leave the panel in your vehicle full time, same size and weight as a laptop in a bag.
    What do you see the advantage of leaving the panel in the vehicle Being? Not going to do a lot of good if you are caught with a flat battery... particularly at the end of the day or in bad weather.

    [/QUOTE]I'll test again with my DC-DC charger inbuilt MPPT charge controller and see if things improve[/QUOTE]

    These things are know to be pathetically over rated and your tests seem to show that. What you were getting was in fact 26W. You don't need a load to test the things. Just measure the amps directly after the controller and the amps you are getting, that will tell you what they are doing. Either that or connect a 100W bulb and measure the amps and Volts. Sounds like to get any worthwhile power out of the things you should keep the whole 4 you bought. Will somewhat undermine the company size and the price advantages though.

    I bought a stack of 190W used house panels this morning for $11 ea. and I got a GTI and some wire , brackets etc.
    At that price I could well afford to take a panel with me and leave it or donate 10 of the things and still be well ahead on the price of these folding ones.
    I wonder how long they will last before something internal breaks or they develop a fault? I doubt they will go 10 Trips.

    OTOH, as you will presumably be in a Vehicle, one could put the cost of the panel towards the cost of a tank of fuel to start and run the engine to charge a batter or provide direct power. I think there would be a LOT of KWH to be had from $145 was it worth of fuel.

  • #28
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,308
    Thanks
    833
    Thanked 1,498 Times in 657 Posts
    Rep Power
    711
    Reputation
    29047

    Default

    Quote Originally Posted by oceanboy View Post
    So output is lousy
    Set up is fiddly and painful
    Takes up heaps of room on the ground
    And moving the panel/blanket around to follow the sun is a pain in the butt
    Being black panel in a black canvas sleeve heat soak was massive, the panels actually smell like hot electrical.

    But packed up size and weight are brilliant.
    You would leave the panel in your vehicle full time, same size and weight as a laptop in a bag.

    I'll test again with my DC-DC charger inbuilt MPPT charge controller and see if things improve
    OB........a question...

    When you say "Takes up heaps of room on the ground".....does that mean you are actually laying them flat on the ground?

  • #29
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by Thala Dan View Post
    OB........a question...

    When you say "Takes up heaps of room on the ground".....does that mean you are actually laying them flat on the ground?
    No, they do have a fiddly bracket you attach at the back so they can be correctly angled at the sun
    But they are 7ft or 2150mm long when deployed, which presents quite a big thing to either walk around or trip over

    You could purchase in a different configuration (IE: 2 x 3) but then they become too hard to angle to the sun



    If you parked in the sun (although we all seek shade) i'd just lay them on the roof rack
    Fast to deploy then and out of the way

    I know other people that do this with those solar panels that are on a flexible plastic backing
    They are also lightweight and perhaps easier to store than a conventional foldable panel
    Last edited by ol' boy; 19-05-19 at 09:20 AM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #30
    Senior Member

    Join Date
    May 2018
    Posts
    724
    Thanks
    179
    Thanked 757 Times in 348 Posts
    Rep Power
    334
    Reputation
    14714

    Default

    You Could always align one side of your tent north and just drape it over that.
    In summer, Flat in a lot of places is in fact the best tilt angle. I have 2 arrays of panels on my south shed roof which are virtually flat, 5o.
    Useless in witwr but crack along in summer. Flatter the panel, the less need/ benefit to orientate them anyway.

    250w House panel is only about 1800 mm long.

  • #31
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by george65 View Post
    If you have noticed the heat soak this time of year, Imagine what they would be like on a clear summers day. Things will be literally melting.
    Agreed, it was a perfect crisp air temp clear day, great for solar generation
    I was really surprised when i packed the foldable panel up after only 1 hour in the sun

    I'd think on a 40 degree day with a north wind, full sun, they would catch on fire or at very least be too hot to touch
    And lets face it, that is the exact weather you need a solar panel as your camp fridge is running overtime
    Last edited by ol' boy; 19-05-19 at 09:37 AM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #32
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by george65 View Post
    You Could always align one side of your tent north and just drape it over that.
    In summer, Flat in a lot of places is in fact the best tilt angle. I have 2 arrays of panels on my south shed roof which are virtually flat, 5o.
    Useless in witwr but crack along in summer. Flatter the panel, the less need/ benefit to orientate them anyway.

    250w House panel is only about 1800 mm long.
    Yeah, something like this was another option george



    Although i'm sure the quoted specs have a bit of mayonnaise on them!
    (How does one produce 250watts from a 1010 x 810mm panel?)



    The light weight and flexibility are appealing for packing in a vehicle
    As said before, these can be cable tied to a roof rack fairly easily once at camp
    Note: I have read and heard that these style of flexible panel can loose 50% of their rated output in 12months
    (not sure why, maybe they get too hot?)

    I'd love a solid house style panel in the bush, 100% they the best once you are there
    But after handling a few traditional folding panels, they weigh a shit load and really don't pack that well
    But are fast and solid to deploy. And easy to move around
    Last edited by ol' boy; 19-05-19 at 09:28 AM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #33
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,308
    Thanks
    833
    Thanked 1,498 Times in 657 Posts
    Rep Power
    711
    Reputation
    29047

    Default

    I have a 160w folding setup - it is bulky, and weighs around 15kg - OK in the caravan, but a pain in the Hiace campervan.

    So, I went for one of those flexible panels you have mentioned - have a mate who has had one on top of his Coaster for years, and still going strong.

    I bought the 120w model, and made a lightweight ground-mount frame out of 30 X 12 hardwood batten, which I fastened to the panel with double-sided tape.

    The whole shebang is 1000 X 670 X 15, and it weighs 3kg.

    It is easy to deploy and move around, and it slides neatly in the rear compartment of the Hiace under the bed, and sits comfortably in the narrow overhead space on top of all the camping and fishing gear.

    With 15 metres of 4mm auto twin cable (22A), I can park the Hiace in the shade and have the panel out in the sun - total resistance of the cable is about 0.4 ohm, so not much loss at the currents involved - thought of using 6mm cable (38A), but bulk and space is a consideration in the camper.

    Camper load is LED lighting, water pump, and a Vitrifrigo fridge - total load about 6.5A with lights and fridge running - battery is a 100Ah AGM.

    On several 3-day trips into alpine trout country, this arrangement has kept us fully functional.

    The regulator I use (several in different applications) is this one - don't be fooled by the MPPT emblazoned across the front - I'm pretty sure it's PWM, but it works fine, and it's totally weather proof:



    Here are some pics of the panel setup:











    This site provides useful information about panel alignment in Oz:


  • The Following 3 Users Say Thank You to Thala Dan For This Useful Post:

    admin (09-08-19),ol' boy (19-05-19),william10 (19-05-19)

  • #34
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,308
    Thanks
    833
    Thanked 1,498 Times in 657 Posts
    Rep Power
    711
    Reputation
    29047

    Default

    Another useful site covering the subject of panel alignment:


  • #35
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Thanks mate, i'll have a read

    I see Bunnings also stock the Projector foldable panel, but that price!!!

    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • #36
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by Thala Dan View Post
    I have a 160w folding setup - it is bulky, and weighs around 15kg - OK in the caravan, but a pain in the Hiace campervan.

    So, I went for one of those flexible panels you have mentioned - have a mate who has had one on top of his Coaster for years, and still going strong.

    I bought the 120w model, and made a lightweight ground-mount frame out of 30 X 12 hardwood batten, which I fastened to the panel with double-sided tape.

    The whole shebang is 1000 X 670 X 15, and it weighs 3kg.

    It is easy to deploy and move around, and it slides neatly in the rear compartment of the Hiace under the bed, and sits comfortably in the narrow overhead space on top of all the camping and fishing gear.

    With 15 metres of 4mm auto twin cable (22A), I can park the Hiace in the shade and have the panel out in the sun - total resistance of the cable is about 0.4 ohm, so not much loss at the currents involved - thought of using 6mm cable (38A), but bulk and space is a consideration in the camper.

    Camper load is LED lighting, water pump, and a Vitrifrigo fridge - total load about 6.5A with lights and fridge running - battery is a 100Ah AGM.

    On several 3-day trips into alpine trout country, this arrangement has kept us fully functional.

    The regulator I use (several in different applications) is this one - don't be fooled by the MPPT emblazoned across the front - I'm pretty sure it's PWM, but it works fine, and it's totally weather proof:
    That is awesome TD, thank you
    I love it.....
    Wow, you sound just like my neighbour here, has a VW synco van, mad fly fisho, always heading to the high country with his van and small trailer nowdays....
    I really agree with where you have arrived, it is pretty much what you need
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • The Following User Says Thank You to ol' boy For This Useful Post:

    Thala Dan (19-05-19)

  • #37
    Senior Member

    Join Date
    Jul 2012
    Posts
    1,308
    Thanks
    833
    Thanked 1,498 Times in 657 Posts
    Rep Power
    711
    Reputation
    29047

    Default

    Yeah...."lower prices are just the beginning"..........right:

    Sneaky way Bunnings makes its ‘lowest prices’ claim

    BUNNINGS lures shoppers with its famous slogan, “lowest prices are just the beginning”. But does it deliver on the promise?


    And just on a side note - remember that when you are taking voltage and current measurements downstream of a PWM controller, your DMM is trying to measure a variable period "square" wave, superimposed on a background DC level.

    So the displayed result may not tell you the whole truth, depending on the nature of your DMM, and the duty cycle and shape of the "square" wave.

    I've found that the easiest way to asses the capabilities of a panel is to run the panel straight into a couple of 100w driving lights and take the measurements.

    This won't tell you anything about the performance of the regulator, but it will give you a pretty good idea of the overall power output capability of the panel itself.

    On another side note - when I last spent time researching the topic, there was some pretty interesting discussion on the 'net about the true extent of the advantages of using MPPT in a mobile type environment. As you probably know, true MPPT regulators aren't all that cheap, and there was a body of opinion that the marginal gains didn't justify the cost.

    Just a thought.

  • The Following 2 Users Say Thank You to Thala Dan For This Useful Post:

    ol' boy (19-05-19),william10 (19-05-19)

  • #38
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Quote Originally Posted by Thala Dan View Post
    On another side note - when I last spent time researching the topic, there was some pretty interesting discussion on the 'net about the true extent of the advantages of using MPPT in a mobile type environment. As you probably know, true MPPT regulators aren't all that cheap, and there was a body of opinion that the marginal gains didn't justify the cost.

    Just a thought.
    Yeah, everyone says PWM are shit, but i've seen side by side tests where the cheap shitty PWM outperformed the MPPT
    How ever, in the long run, the MPPT should track the best power point over time
    But interesting as you say, they are not that bad for our application

    BTW TD, i have found this kid rather helpful and he also debunks a lot of stuff
    And i like that he Real World tests things, with live results

    Last edited by ol' boy; 19-05-19 at 11:26 AM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • The Following User Says Thank You to ol' boy For This Useful Post:

    Thala Dan (19-05-19)

  • #39
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    This is also a good look at the different panels

    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • The Following 2 Users Say Thank You to ol' boy For This Useful Post:

    Thala Dan (19-05-19),william10 (19-05-19)

  • #40
    Premium Member
    ol' boy's Avatar
    Join Date
    Jan 2008
    Posts
    16,699
    Thanks
    7,614
    Thanked 9,335 Times in 4,744 Posts
    Rep Power
    3934
    Reputation
    161772

    Default

    Another option for a foldable 120W panel
    (I'd say this is better than what i purchased, as everything has proper 50Amp Anderson Plugs and cabling looks heavier and the Solar Controller is much better.

    Last edited by ol' boy; 19-05-19 at 12:11 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

  • Page 2 of 3 FirstFirst 123 LastLast

    Bookmarks

    Posting Permissions

    • You may not post new threads
    • You may not post replies
    • You may not post attachments
    • You may not edit your posts
    •