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

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    Default How to select a good 12volt solar panel?

    So many camping style panels on the market, most people look at Max Current output, but what about Max voltage output?
    Apart from production quality and silicon quality, my question surrounds Max Panel Voltage

    As MPPT controllers have such a wide range of input voltage, is a higher max voltage beneficial when selecting a camping panel?
    I know we all look at Amp output, but i see some panels quote 18v Max and another might be 22.5volt Max
    The new breed of Projector IDC DC-DC (MPPT) chargers have increased Solar Input voltage from 23v Max to 29v Max.
    These are all for 12volt systems

    Or is it better to start with a voltage closer to what you need so the MPPT doesn't have to do so much work converting it to a useable voltage for charging?

    I ask this, as Kogan have an affordable range of panels

    The current output seems great, but the voltage seems low compared to others

    I have always liked the idea of a higher panel voltage, as that would allow better voltdrop on the connecting lead that is run out from your vehicle, which might be 5 or 10M long.
    Of course this means the MPPT charger is mounted next to your battery, not on the panel.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!



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    Crazy Diamond
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    I use the dollar per watt formula for value.
    Then match the voltage to the equipment I already have or am purchasing.
    Cheers, Tiny
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    There is very little difference in the voltage.
    Either you have so called 12V panels that have their maximum power point around 18V while 24V panels have it around 36V.
    The so called max. voltage you quoted is irrelevant. This is the open circuit voltage and is usually 21-22V.
    You need to know the MPP voltage: voltage under maximum delivered power.
    A good quality MPPT controller will always get the optimum out of them and it doesn't really matter if it gets 17 or 19V input.
    It only needs to output around 14V for bulk charge.
    What matters is the sunlight the panels get and you will always find that the panels will provide significantly less than specified in practical use.

    I don't believe in spending big bucks for 5% extra power on 'high quality' panels.
    Truth is that panels get better AND CHEAPER almost from year to year.
    What if find is that newer panels have improved performance under cloud but I did not notice a higher open circuit voltage lately. They all seem to be 21-22V.

    What you mentioned about having the charge regulator on the panels and not with the battery is a big NO for me. Remove it from the panels and find a way to connect it as close to the battery as possible. I have the regulator built inside the battery box.
    However if it is just for camping I wouldn't bother if it is only few meters of cable.
    Last edited by Uncle Fester; 09-05-19 at 08:41 PM.
    This era of thoughtless consumption must end so we can encourage a world of creative geniuses rather than consumer idiots.


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    Quote Originally Posted by nomeat View Post

    What you mentioned about having the charge regulator on the panels and not with the battery is a big NO for me. Remove it from the panels and find a way to connect it as close to the battery as possible. I have the regulator built inside the battery box.
    However if it is just for camping I wouldn't bother if it is only few meters of cable.

    Did i mention that?
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    .
    Last edited by Uncle Fester; 09-05-19 at 09:10 PM.
    This era of thoughtless consumption must end so we can encourage a world of creative geniuses rather than consumer idiots.


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    I use a 120w folding panel from Rich Solar, first thing i did was remove the regulator from the back of the panels and mounted it in the battery box of my camper trailer.
    Reg is just a cheap PWM but it works well with my meager power needs and in good sunlight keeps my 145AH battery charged enough to run a 50ltr waeco, stereo and led lights.

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    I think its common knowledge to mount your solar charge controller or DC-DC as close to your Deep Cycle battery as possible

    I'm just interested in the vastly different Max Voltage Specs from panel to panel
    Can that be beneficial?
    Is it an indication of better silicone being used?

    As so many DC-DC chargers have recently upgraded their voltage range for solar 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!

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    The max Voltage is related to the number of cells in the panel and the way they are wired in series/ parallel. Probably has to do with the actual layout on the panel as well for production purposes ( cheap) .

    Output wise it probably makes little difference in reality. Charge controllers have minimal start up values so a panel with a higher voltage could boot the controller up sooner and finish later in the day. That said, the Voltage is irrelevant as it is converted by the controller to what is needed and even if the panel was hooked to some loads direct, still makes little difference.
    Higher voltage will be pulled down to the required voltage at certain amps. Panels of the same rating in watts with lower voltage will just do higher amps. 6 of one, half a dozen of the other.

    I was playing today with one of my arrays powering a water heater element. The power coming from the array was 298V and there is about 3.2 KW of panels on that string.
    The heater element was 3.6Kw@ 240V. When I hooked the panels up the volts fell to just over 200. I have run strings that totalled over 350V to 240V resistive loads and as long as the total WATTAGE from the panels is not greater than the wattage of the load, the beaut thing about panels is they just pull down to a lower voltage and balance out. You won't blow a resistive load whatever voltage you feed it from panels as long as the wattage is not higher than the draw of the load. The panels just self level if you like and also panels virtually never give full output especially if they are a few years old.

    These camping panels seem like one hell of a rip off to me. I buy used 250W panels for $20 ea. These camping panels for $250 are a rip off in my book.
    It's also pretty well known that most of them from the Chinese sellers are over rated as hell like most other Chinese things especially on fleabay and the like. The Chinese just have no honour or moral standards and are dishonest as hell with most things they make. If something says 300W, I reckon you'd be lucky for it to make 225w under perfect conditions.
    They seem to think big numbers sell better and often ratings are just pure and utter fantasy and have no relationship to reality.

    If I were going to take a panel camping it would be a full size house hold one. Loads cheaper and probably more reliable as well. Many of these camping panels are thin film which means they are stuffed in virtually no time compared to the traditional types.

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    My 12v 200w panel (off ebay) has been charging a 100ah battery for a few years now..(mppt charger located next to batt)
    It's wired to run 8 x 15w led lights under my verandah and shed light. That's the only load I have connected to it so it should last many more years.

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    Bargain right here.


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    Quote Originally Posted by loanrangiel View Post
    Bargain right here.

    Agreed, that is a great price for Bunnings and a Foldable

    Especially when you look at this:



    Might get Anaconda to price match
    Last edited by ol' boy; 17-05-19 at 12:03 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!

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    Quote Originally Posted by loanrangiel View Post
    Bargain right here.

    Thank you loanrangiel...

    4 purchased this morning.
    Deleted item at Bunnings, still top dollar at Anaconda...

    Very compact and lightweight
    Comes with a stand and tough canvas bag

    Last edited by ol' boy; 17-05-19 at 05:46 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!

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    I should get another but i have a folding panel as well.

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    Quote Originally Posted by oceanboy View Post

    4 purchased this morning.

    4! How many do you need?
    Cheers, Tiny
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    The information is out there; you just have to let it in."

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    Quote Originally Posted by Tiny View Post
    4! How many do you need?
    When it comes to a bargain (particularly for camping or fishing) what's "need" got to do with it?

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    I'm only having 2 of them Tiny.... The others are all for friends.
    They are low on voltage output compared to Kings *
    And the PWM controller is a toy. The cable size is also pathetic
    The positive is i just fitted 4 Solar panels (well blankets in my car) and it didn't even take up the space of a small esky

    *

    I'll give one a test tomorrow

    I like the idea of a solid 250Watt panel roof rack mounted or a Bi-Folding 200Watt panel, but the size and weight are a issue for storage and packing
    They are more stable when set up at camp though, and they probably cool better.

    Oh well, these are convenient. I'll see what they produce tomorrow
    Last edited by ol' boy; 17-05-19 at 08:33 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!

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    My local bunning didn't have any....

    Sent from my VOG-L09 using Tapatalk



    Finally got FTTN, 710m line length....

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    Quote Originally Posted by hoe View Post
    My local bunning didn't have any....

    Sent from my VOG-L09 using Tapatalk
    I had to ring around a few different Bunnings
    The first told me which stores had them and how many
    But then ringing each store directly returned different results again.

    Turns out they are a "Deleted" item
    So they will not be re ordering them in, thus i found mine not even on a shelf, but in a random trolly with other camping products

    I think they are probably no better than any Chinese eBay version for similar price
    They got me over the line because they were so light and packed up so small, could keep one under your car seat

    From my searching, looks like that whole range has been rebranded "Roman"



    This might explain why they are a deleted stock item in Bunnings.
    Last edited by ol' boy; 17-05-19 at 08:45 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!

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    Next one is 600km away.....

    Might go down in the morning and see if I can find one....

    Sent from my VOG-L09 using Tapatalk



    Finally got FTTN, 710m line length....

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    Quote Originally Posted by oceanboy View Post
    I'm only having 2 of them Tiny.... The others are all for friends.
    They are low on voltage output compared to Kings *
    And the PWM controller is a toy. The cable size is also pathetic
    The positive is i just fitted 4 Solar panels (well blankets in my car) and it didn't even take up the space of a small esky

    *

    I'll give one a test tomorrow

    I like the idea of a solid 250Watt panel roof rack mounted or a Bi-Folding 200Watt panel, but the size and weight are a issue for storage and packing
    They are more stable when set up at camp though, and they probably cool better.

    Oh well, these are convenient. I'll see what they produce tomorrow
    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

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