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  1. #1
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    Default Solar power and Battery systems

    Does anyone have any preferences towards solar panel arrays?

    2x 80w panels should be sufficient to power a small system, this is great but the amount of "fixed" space required is rather large.
    4x 40w panels would be much easier to pack in and take with but what are the draw backs?

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    I am on a solar mission as well. So far the 150W inverter I have is a waste, the 170W (2 x 85w) panels + 102AH battery barely makes up as a redundancy to my CTEK 250S and 102AH in the bakkie. Fridge, laptop, charging camera batteries and LED lamps. Laptop kills an inverter and I need the thing for photo editing.

    Testing the Dual battery this weekend to see what the actual consumption is and compare it with the math.

    I prefer less than more. The single panel is too big and 4 panels too cumbersome for my liking. Setting up, wires, connection etc...but I am not even that far.

    I have so much conflicting info on what you need, that my efergy e2 is going with me and I am collecting some data this weekend to see what is required for my setup from actual figures.

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    When you day they barely make up a redundancy, does that mean they are unable to cope with your needs or you have not needed them?

    I have a 102a battery being charged via a d250s and one 80w panel at the moment that is being used for the fridge. Unfortunately it didn't test out too well when I was away (may have something to do with people standing around with the fridge open while having beers ) my fridge runs at about 6.3a from its initial start so I'm thinking 160w+- should do the trick.

    Would be interested to hear how it goes your side for some idea going forward.

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    Your statement is exactly my concern. I only recently installed the CTEK and always had the normal D/Bat system that never really worked.

    In the perfect world it seems to add up, but if you are in the bush for 2 weeks, then things change quickly. I have done some math but have it at the office and is a work in progress.

    Example:

    Optimum: 170W for 6 hours sun x Efficiency 95% = 0.969kWh

    My fridge (Snomaster 66L) draws 12VDC, 2.5A-4,5A = 48Watt/h (using 4.0A nominal). My laptop charger is rated 230VAC at 1.8A = 414watt so I need a 500W minimum inverter. Need to charge my camera batteries, LED lamps, phone etc as well.

    It is the frequency of use, equipment power consumption and ambient temperature(fridge) that determines the endurance of the system. Each person has individual habits and equipment. What works for one doesn't always work for the other.

    The problem is averaging it all out from nursing the system, optimum and maximum loads. Will see what happens and give some feedback.

    Edit:
    Also take into consideration that I was advised not to discharge past 20%. So the 102AH is only an effective 80AH. I also read that opportunity charging (quick charging between uses) is detrimental to battery life? Dunno?
    Last edited by AntonN; 2015/07/13 at 09:42 PM.

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    Default

    Quote Originally Posted by Kaydee View Post
    Edit:
    Also take into consideration that I was advised not to discharge past 20%. So the 102AH is only an effective 80AH. I also read that opportunity charging (quick charging between uses) is detrimental to battery life? Dunno?
    The "past 20%" actually means "20% of rated capacity" and is the generally accepted rule of thumb for starter batteries, so 20% capacity of a 102 Ah battery would be 20.4 Ah. For deep-cycle, it is usually 50%.
    ZS6VL


  6. #6
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    Default

    Im sure this equates to the same thing as the 50% but I heard that you shouldnt take your battery past 10.5V as it may cause damage. If you look at the graph of amp/volt vs time this probably comes out at 50%.

    The thing that is really frustrating is that my snowmaster seems to read the voltage level incorrectly (in comparison to two of my other monitors) and cuts out sooner rather than later, meaning I get to use even less of my battery potential.

  7. #7
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    Quote Originally Posted by nicksimp08 View Post
    Im sure this equates to the same thing as the 50% but I heard that you shouldnt take your battery past 10.5V as it may cause damage. If you look at the graph of amp/volt vs time this probably comes out at 50%.

    The thing that is really frustrating is that my snowmaster seems to read the voltage level incorrectly (in comparison to two of my other monitors) and cuts out sooner rather than later, meaning I get to use even less of my battery potential.
    This makes it even worse. Maybe the answer is the a 200AH in my backup system? I am going to check and record actual loads this weekend.

    I noticed this with the Snomaster. What next...

    On the lighter side, I have two choices:
    Eat dry food and drink warm beer...

    or...

    The bakkie must look like this!!!
    Attached Images Attached Images  

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    Quote Originally Posted by Kaydee View Post
    This makes it even worse. Maybe the answer is the a 200AH in my backup system? I am going to check and record actual loads this weekend.

    I noticed this with the Snomaster. What next...

    On the lighter side, I have two choices:
    Eat dry food and drink warm beer...

    or...

    The bakkie must look like this!!!
    Haha, looks like it could power a house. In this kind of weather we should be fine for fridges (being cold at the moment/closer to ambient), for summer it may be more troublesome but with more light to make use of.

    As long as the panels can put in enough to offset the usage of the fridge during the day, which you can then turn off at night, it may work.

    If you go with the additional battery you may want to build a porta pack which you can use for your lighting and inverter etc and leave the fridge on its own standalone system. Maybe add a plug that you can connect the porta pack back into the system to charge?

    What sort of current does your inverter draw? Out of curiosity I ran my dremel on my 150w inverter and it was pulling +9a of current.
    If the laptop and fridge are running at the same time that would probably drain a single battery in no time (I keep mine separate to avoid flattening my starter battery).

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    I think this system should be okay...

    Now I am going to do a habit study to determine charging frequency and worst fridge power consumption.

    Why am I doing this all...because I want to go on holiday for two weeks and not sit and think about power but enjoy the trip.
    Attached Images Attached Images  

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  11. #10
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    Quote Originally Posted by Kaydee View Post
    I think this system should be okay...

    Now I am going to do a habit study to determine charging frequency and worst fridge power consumption.

    Why am I doing this all...because I want to go on holiday for two weeks and not sit and think about power but enjoy the trip.
    Are you sure the panels put out 14A collectively? From what I have been seeing the 80w panels put out a max of about 4A. Charging times may vary as well as the d250s charges in stages, but it does also take excess voltage and convert it to extra amps for charging.

    Also remember to take the battery curve into account.

    Something that may be of use:
    http://www.marxrv.com/12volt/12volt.htm
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  12. #11
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    Quote Originally Posted by nicksimp08 View Post
    Are you sure the panels put out 14A collectively? From what I have been seeing the 80w panels put out a max of about 4A. Charging times may vary as well as the d250s charges in stages, but it does also take excess voltage and convert it to extra amps for charging.

    Also remember to take the battery curve into account.

    Something that may be of use:
    http://www.marxrv.com/12volt/12volt.htm
    This is my issue with conflicting info, not meaning yours. These solar panel suppliers all have different theory and quote figures that does not make sense. I was quoted a 20A controller for the 2 panels supplying 14A charge (170w x 12v=14.16A)? The supplier reckoned my 102AH will be charged in 6 hours!

    Thanks for your info. Any more accurate theory behind it will be appreciated.

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    Default

    Hopefully I am not leading you astray as I am new to the solar game as well, its just a general trend that I've been picking up while looking to get some new panels. It seems you can get panels with a higher A but still not at the specs you were quoted it seems. Again it could be the charger converting excess voltage into more current.

    Just a few random stats:
    SD ECO 75 - 75W - 22.0V - 5.21A
    SD ECO Plus - 80W - 22.2V - 4.44A (5.56A short circuit)
    SW 80 poly RNA - 80W - 21.9V - 4.49A (4.78A short circuit)
    SW 85 poly R5A - 85W - 22V - 4.19A (5.2A short circuit)
    SD ECO 100 - 100W - 22.1V - 6.89A
    SD ECO Plus - 100W - 22.2V - 5.44A (6.89A short circuit)

    Also note that these are more than likely standard testing conditions so will more than likely be rated higher than what we can achieve.

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  15. #13
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    Quote Originally Posted by nicksimp08 View Post
    Hopefully I am not leading you astray as I am new to the solar game as well, its just a general trend that I've been picking up while looking to get some new panels. It seems you can get panels with a higher A but still not at the specs you were quoted it seems. Again it could be the charger converting excess voltage into more current.

    Just a few random stats:
    SD ECO 75 - 75W - 22.0V - 5.21A
    SD ECO Plus - 80W - 22.2V - 4.44A (5.56A short circuit)
    SW 80 poly RNA - 80W - 21.9V - 4.49A (4.78A short circuit)
    SW 85 poly R5A - 85W - 22V - 4.19A (5.2A short circuit)
    SD ECO 100 - 100W - 22.1V - 6.89A
    SD ECO Plus - 100W - 22.2V - 5.44A (6.89A short circuit)

    Also note that these are more than likely standard testing conditions so will more than likely be rated higher than what we can achieve.
    Not at all. I appreciate the info. I also read the data sheets they provided me and this was received.


    SD ECO PLUS 85Wp

    Open circuit voltage (Voc): 22.2V

    Optimum operating voltage (Vmp): 18V

    Short circuit current (Isc): 5.72A

    Optimum operating current (Imp): 4.72A x 2 = 9.4A

    Maximum power at STC (Pm) 85Wp

    If I have 9.4A at maximum and need to recharge a 102AH battery that has drained to 50% capacity then;
    51AH / 9.4A = 5.5hrs?

    Given you have a clear day and lots of sunshine. Makes more sense this way. I am just cautious in spending money the wrong way and realise later on I needed more or less. Seems this will do the job.

    What I need to establish is the frequency that the fridge switches on and off. This I will record with the efergy E2 and take ambient temperature and amount of times I open the fridge. Lets see.




  16. #14
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    Quote Originally Posted by Kaydee View Post
    My laptop charger is rated 230VAC at 1.8A = 414watt so I need a 500W minimum inverter. Need to charge my camera batteries, LED lamps, phone etc as well.
    IMHO, this is one of you biggest problems.

    You're wasting energy here. It cost power to covert power. Any inverter will give you losses of at least 10% just to convert the power.

    What you're doing here, is to take 12V and stepping that up to 220V for your laptop, and your laptop's inverter steps this down again to whatever is required for your specific laptop. (Mine requires 19.5V)

    Lots of energy wasted me thinks.

    I think a much more energy effecient way is to purchase one of those inverters designed for laptops.

    It steps up or down to what Volts is required from either 12V or 220V.

    I bought one that is very compact with different plugs to select from, and you're able to select via a switch anything between 12V and 24V. It costed only R200.00

    Marvelous little gadget.

    You may be able to use this for your rechargeable batteries as well, depending on how they are charged (in unit itself, or removeable).

    Just my 2C
    Last edited by Die SwartKat; 2015/07/16 at 11:01 AM.
    Nico Swart

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    Default Thread Hi-Jack.

    This thread (although interesting) is a classic example of how a thread can be hi-jacked and steered into a different direction.

    1. The OP asked about the merits of selecting 4 panels of 40W each as opposed to 2 panels of 80W each.

    2. Poster #2 then asks his own question about his own "solar mission" and the thread sets off in another direction.
    Eggie.

    "Do not go where the path may lead, go instead where there is no path and leave a trail."
    - Ralph Waldo Emerson.

  18. #16
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    Yet, it doesn't appear to bother the OP at all.

    Lots of information being shared that will benefit other members.

    The original question in any event is something everyone has to figure out for him/herself depending on vehicle type, roofracks, packing systems etc etc.

    There is no right or wrong answer.
    Nico Swart

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  20. #17
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    Hi nicksimp08

    Can we continue in this direction on your original post or should I start a new thread? It is just getting interesting and to start afresh, this train of thought will be lost with a new thread.

    It is up to you.

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    Quote Originally Posted by Kaydee View Post
    Hi nicksimp08

    Can we continue in this direction on your original post or should I start a new thread? It is just getting interesting and to start afresh, this train of thought will be lost with a new thread.

    It is up to you.
    I'm chilled, lets rename the thread, some good information and discussion going back and forth here.

    Any Ideas for a title?

  22. #19
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    Quote Originally Posted by nicksimp08 View Post
    I'm chilled, lets rename the thread, some good information and discussion going back and forth here.

    Any Ideas for a title?
    That's great!! Thanks.

    Some, not all, suppliers of these systems feed on the lack of knowledge and if you don't query or ask, you might end up with substandard equipment or not at all suitable solution. That is money down the drain...

    Collectively we prevent each other from wasting our cash. Is that not what the forum is for. Sharing knowledge. Thanks of course for your input, and the other guys, it helps a lot!

    It is your thread so change it to something short and descriptive...

    Solar power and Battery systems?

  23. #20
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    Quote Originally Posted by Die SwartKat View Post
    IMHO, this is one of you biggest problems.

    You're wasting energy here. It cost power to covert power. Any inverter will give you losses of at least 10% just to convert the power.

    What you're doing here, is to take 12V and stepping that up to 220V for your laptop, and your laptop's inverter steps this down again to whatever is required for your specific laptop. (Mine requires 19.5V)

    Lots of energy wasted me thinks.

    I think a much more energy effecient way is to purchase one of those inverters designed for laptops.

    It steps up or down to what Volts is required from either 12V or 220V.

    I bought one that is very compact with different plugs to select from, and you're able to select via a switch anything between 12V and 24V. It costed only R200.00

    Marvelous little gadget.

    You may be able to use this for your rechargeable batteries as well, depending on how they are charged (in unit itself, or removeable).

    Just my 2C
    Excellent! Thanks for that idea. Output on my charger is 20VDC at 3.5A. Lenovo.

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