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  1. #21
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    Default Re: Solar decisions

    Thank you. This is helpful.

    Quote Originally Posted by JLK View Post
    a cell phone not nearly as indicated.
    They didn't look right but that is what I got from the technical spec docs.

    Quote Originally Posted by JLK View Post
    80 watt panel will theoretical provides 80/14vx7hx.9eff= 36 Ah , if you move it around the catch max sun

    The tables are there if you use reply. A fridge draws about max 50 Ah per day or 600watts in hot conditions, depends also how you uses it, and a cell phone not nearly as indicated. LED light consumption you can ignore. 160 watt panel can give you easily 160watt/14v x 6h x .9eff from the ctek, about 60 ah at peak charging. An hour or so charging from the alternator will see you through easily.
    So if I use your formula with my planned 3x 90watt panels I could expect to get something like the following:

    270watt / 14v x 6h x .9eff = 104ah

    Does this mean that I could fully charge my 108ah battery in the 6hrs of sunlight (and I move it around the catch max sun) and if it was depleted by 80%?

  2. #22
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post
    270watt / 14v x 6h x .9eff = 104ah

    Does this mean that I could fully charge my 108ah battery in the 6hrs of sunlight (and I move it around the catch max sun) and if it was depleted by 80%?
    Yes more or less. Formulae thus not work exactly like that in practice but its good enough.
    Johan Kriel

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  4. #23
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    Default Re: Solar decisions

    Quote Originally Posted by JLK View Post
    Yes more or less. Formulae thus not work exactly like that in practice but its good enough.
    Yes, real world circumstances differ vastly sometimes from theoretical circumstances on paper.

    But I agree, with 3 x 90W he should be well off.
    Nico Swart

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  6. #24
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    Default Re: Solar decisions

    Quote Originally Posted by Die SwartKat View Post
    Yes, real world circumstances differ vastly sometimes from theoretical circumstances on paper.
    If you put a girl 100 m off and only allow to get closer in steps of half the distance you will never get to her according the number crunchers, but in real world you will get close enough.
    Johan Kriel

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  8. #25
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    Default Re: Solar decisions

    Can the CTEK you use take 300W input?
    You can even go for 2x 140W or 150W panels, which ever will fit the best on the Bundutop.
    It's in pubs where the world's greatest ideas begin.

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  10. #26
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    Default Re: Solar decisions

    Quote Originally Posted by bigboy529 View Post
    Can the CTEK you use take 300W input?
    You can even go for 2x 140W or 150W panels, which ever will fit the best on the Bundutop.
    According to the technical specifications, it can.

    Bushpower site it says this Maximum input watts on solar input 250 Watts.

    However:
    Solar panel power: 50-300W (max. solar panel open-circuit voltage 23V DC)

    And the manual on page 14, says "Maximum solar panel power - 50-300W (Max OCV solar panel 23V)

    I haved also spoken to Melt from Enertec who is the "CTEK National Brand Manager" and he confirmed that the D250SE can handle 300W.

    So I am going to go with it can handle 300W.

    All the 140w and 150w panels I have looked at are too long to fit if I want to put more than one up on top of the Bundutec.

    thanks for the comments and feedback guys, really appreciate it.

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    Thumbs up Re: Solar decisions

    Well, that's a good idea and a perfectly done worksheet.

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  13. #28
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post
    My thinking around having more than one (3x 90w in my case) is that if I wire them in parallel and one stops working the other 2 will continue. The fairy light analogy was explained to me here. if one stops working you don't lose all power harvesting capabilities.
    Quote Originally Posted by Dungbeetle View Post
    Careful with large single panels. Rather have 2 x 80W hinged together. And make them portable.

    To me being forced to park in the sun to keep beer cold makes no sense at all
    I didn't see a notification to these replies, my bad.

    You make a good point on that if one goes you're out of power. Definitely a valid point.

    I'll give the single 120 a try and my plan was to add a second 120 (the WRND accepts up to 265w max).

    I am also planning to make it removable from my roofrack and run an extension.

    I'm still a newbie to solar so I'll look at and experiment with my current plan for weekend camping, hopefully soon be able to egt out there lol.

    My longer term (bucket list) goal is a tour of Nam. So by then redundancy (second panel) will be a must.

    But until then, should my one panel konk out, I'll be able to survive the weekend away and get home safe
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  15. #29
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    Default Re: Solar decisions

    You guys are way to worried about panels packing up or breaking.

    The only way I see this happening is if:

    - you crash or roll your vehicle (stuffed in any way an the panels will be least of your worries)
    - you place your panels in an elephant or hippo pathway and they get trampled.

    And in the very most highly unlikely event that one just stops working, to rewire is easy and should not take more than 10 minutes.
    Nico Swart

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  17. #30
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    Default Re: Solar decisions

    Quote Originally Posted by Garthox View Post
    My longer term (bucket list) goal is a tour of Nam. So by then redundancy (second panel) will be a must.
    My longer term plan (the one including my other fridge) is to add a portable battery box (not sure which one yet .. or if I should build my own ... because I LOVE doing that kind of stuff). The thinking behind a 2nd auxiliary battery being portable is that I will be able to take it out and put it and the little fridge in Swambo's Discovery for when we do short little jollies.

    When this portable battery is in the Defender I will hook it up to the 1st auxiliary battery in parallel using an Anderson plug. However, when we stop I want to be able to unplug this battery from the one that is permanently in the Defender and plug a portable solar panel into it via a longish extension (into that same Anderson plug) so I can move the panel around in the direct sunlight...etc etc

    I hope this makes sense ...

    Quote Originally Posted by Garthox View Post
    But until then, should my one panel konk out, I'll be able to survive the weekend away and get home safe
    this is a pity ... I rather get stuck away from home and the rat race ... ask me how much I have loved the lockdown ... and how terrified I am about having to go back to clients ...

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  19. #31
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post
    My longer term plan (the one including my other fridge) is to add a portable battery box (not sure which one yet .. or if I should build my own ... because I LOVE doing that kind of stuff). The thinking behind a 2nd auxiliary battery being portable is that I will be able to take it out and put it and the little fridge in Swambo's Discovery for when we do short little jollies.

    When this portable battery is in the Defender I will hook it up to the 1st auxiliary battery in parallel using an Anderson plug. However, when we stop I want to be able to unplug this battery from the one that is permanently in the Defender and plug a portable solar panel into it via a longish extension (into that same Anderson plug) so I can move the panel around in the direct sunlight...etc etc

    I hope this makes sense ...
    Lol, it is like I am reading my own thread notes.

    I like your idea of an extra portable aux battery. It seems it'll definitely be useful in our case.
    From what I have read on the forum, it isnt too difficult to do.
    And it seems you're like me , in that we enjoy the DIY stuff almost as much as camping.

    I'll be keen to see how you come right with these plans
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  21. #32
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    Default Re: Solar decisions

    Quote Originally Posted by Die SwartKat View Post
    You guys are way to worried about panels packing up or breaking.

    And in the very most highly unlikely event that one just stops working, to rewire is easy and should not take more than 10 minutes.
    I take your point Nico. Here's my problem though: My D250SE can only take a maximum of 23v in from the solar panels. So some of the bigger panels are immediately ruled out as their voltage coming from the panel is way more than that. There are some smaller ones that I can use, so I have to decide if I go with say a single 150W panel (22.8v VOC) with an output of 8.34 A ... or a single 160W panel (22.7v VOC) with an output of 9.13A.

    The way I reason is ... I could put x3 90w panels the input voltage would remain at 21.7v (within the limits of my Ctek charger) but the output amps would now be 15.33A

    This is what the first post was all about... surely x3 90w panels (which I would have to wire up in parallel) would be better for my needs that one 160w panel?

    By the way ... here is an excellent article weighing up the pros and cons of wiring panels up in series vs parallel for anybody that is interested.

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  23. #33
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    Default Re: Solar decisions

    Quote Originally Posted by Die SwartKat View Post
    You guys are way to worried about panels packing up or breaking.
    Don't we see more worries that are unlikely to happen

  24. #34
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post
    I take your point Nico. Here's my problem though: My D250SE can only take a maximum of 23v in from the solar panels. So some of the bigger panels are immediately ruled out as their voltage coming from the panel is way more than that. There are some smaller ones that I can use, so I have to decide if I go with say a single 150W panel (22.8v VOC) with an output of 8.34 A ... or a single 160W panel (22.7v VOC) with an output of 9.13A.

    The way I reason is ... I could put x3 90w panels the input voltage would remain at 21.7v (within the limits of my Ctek charger) but the output amps would now be 15.33A

    This is what the first post was all about... surely x3 90w panels (which I would have to wire up in parallel) would be better for my needs that one 160w panel?

    By the way ... here is an excellent article weighing up the pros and cons of wiring panels up in series vs parallel for anybody that is interested.
    Agree absolutely. In a small mobile system like you and I use it makes no sense to go series, parallel is the way to go always.

    Provided space is not too much of an issue, the 3 x 90W is also the way I would go. How will you transport them?

    To hinge them will become a heavy story, but do try and keep them portable as well.

    I like mine (well at least on of them on my setup) open at all times for when you do that quick 30min or hour stop along the road for coffee or breakfast break, or park at a shop to stock up - to slowdown the battery draining. With very very little effort, I can have them both open and it also creates a small afdak at the rear where the fridge is accessed.

    And then I have a 15m cable to move them to a sunny area if I absolutely must whilst vehicle is in the shade for longer stints.

    Point I'm trying to make, keep your system as flexible and versatile as possible to cater for most circumstances.
    Nico Swart

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  25. #35
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    Default Re: Solar decisions

    I have also just stumbled onto this great explanation (Well I found it helpful anyway):

    Battery Charger Selection By Calculation Example

    Below is a sample calculation to determine which of our products would best suit your
    requirements.

    1. Determine the battery voltage - 12 volt or 24 volt
    2. Determine how many batteries are to be charged (1,2,3 or 4)
    3. What are the battery capacities (Ah, Amp-hours)?
      • Add them together
      • e.g. 2 x 60Ah, 1 x 100Ah = 220 Ah total

    4. What re-charge time is required?
      • (6 hours minimum, usually 24 hours maximum - if not known, assume 10 hours)

    5. Divide TOTAL Ah by the re-charge time to get CHARGING CURRENT
      • e.g. 220Ah / 10 hours = 22 AMPS.

    6. ADD 20% to allow for battery in-efficiency
      • i.e. 22 AMPS + 20% = 26.4 AMPS

    7. Is there any additional load current on the battery during re-charging? If so, add this to the CHARGING CURRENT.
      • e.g. 24 WATTS / 12 VOLTS = 2 AMPS



    CHARGER CURRENT REQUIRED = 26.4 AMPS + 2 AMPS = 28.4 AMPS.


    Note: Much too big a charger could damage the battery and too small will take longer to re-charge.



  26. #36
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    Default Re: Solar decisions

    Quote Originally Posted by Die SwartKat View Post
    How will you transport them?
    By my calculations (and weight comes into it as you can see from my first table in the original post) I can put x3 90w panels permanently on top of my Bundutek rooftop tent and remain within the weight limitations.

    I must say .. even though this setup may not be everybody's cup of tea all the comments are certainly helping point me in the direction I think I need to go to suit my requirements.

    Thanks again guys!

  27. #37
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post
    SORRY GUYS: I had laid out beautiful tables and links in order to make this post easily readable. Spent ages trying to get it all sorted only to find out that the tables had been removed and now there is no way to make this much better. Comon admins surly this can be sorted. If you need help give me a call. Images of the tables are one way to skin a cat!

    The time has come to add solar to my over-landing experience ... and WOW is there a TON of information out there. I apologize if this is a horribly long post. I have included a spreadsheet of the table including some current prices if you are interested.

    Side note: I am of the opinion that if you are going to do something, do it right the first time. Even if I have to do it in stages from an affordability perspective.

    This is the homework I have done and I don't necessarily want a recap of the many many excellent posts out there. I just what direction as to what I am potentially missing, and man am I confusing myself. I have compared several panels found on the web and have come up with a table to try to help me make the decision on which panels to get. This link has also been VERY helpful with the calculations I think I needed.

    Here are my restrictions though:
    1. I will be adding this system to the top of my Bundutec RTT and there are a few limitations here that I am aware of (see the manual in the link provided):
      1. The roof can carry 25kg
      2. Length is 2100mm and I don't want the combined width of my panels to exceed that.
      3. Width is 1350mm and I don't want the length of my panels to exceed that.

    2. I use a C-tek D250SE charger that I want to plug the panels into. There are 2 limitations here that I am aware of:
      1. Input voltage on the D250SE is limited to 23v
      2. Max input current is 25A

    3. My auxiliary battery will be a Blue Nove LiFePO4 108Ah (I am not sure if I should get the one with Bluetooth management included. the link is to the battery without the Bluetooth.)
    4. Later I want to add another LiFePO4 battery (like the one in point 3) but in a portable box that I can add to my system for over-landing (I.e. 1x battery per fridge) but also have the ability to move it to SWAMBO's Disco for when we shoot somewhere and I want cold drinks on the way.
    5. Multiple panels will be wired in parallel so I can maximize the amps while keeping the Voc low (under 23v)


    Here is the table that is helping me make up my mind about which panels I think I need:

    Attachment 574195

    Is this understanding correct?
    So for running the 50l fridge and all the other accessories listed below, I think the calculation will look as follows:

    Total Expected Usage:
    Attachment 574196

    Total Watts Needed over 24 hrs (excluding the 40l fridge) -
    1905.6 W

    To work out the amperage needed I divided 1905.6W / 12v and came to 158.8A

    Battery:

    108Ah Battery @ 80% = 86.4A
    convert to Watt-hours = 1036.8

    Huh? I thought I had a little understanding of what I needed but now I am all confused again.


    1. How will I ever be able to keep up with that load requirement?
    2. From my calculation, it looks like I will need double the capacity I have, and I havent even added my other fridge yet?
    3. How are you guys working out with something like an 80w panel and not moving for 2 - 3 days?
    4. Where have I gone wrong in these calculations?

  28. #38
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    Default Re: Solar decisions

    Hi,
    Send your info to my email. [email protected] I will help you with your design and options.

  29. #39
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    Default Re: Solar decisions

    Quote Originally Posted by AcidHawk View Post


    Total Expected Usage:
    Attachment 574196



    Hi Acid

    Check this Youtube for a test running a CF50 fridge. Never went over 4 Amps. I did test it with a high-end Multimeter a well. The result was very similar.
    That 7 Amps stated is over specced on paper in my opinion. They obviously allow for tolerances, as all OEMs does.

    CF 50 test - https://www.youtube.com/watch?v=kCHplnNUi00
    NL 50l Test - https://www.youtube.com/watch?v=pHFRiGo6_xw
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  30. #40
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    Default Re: Solar decisions

    Quote Originally Posted by Nerd View Post
    Hi Acid

    Check this Youtube for a test running a CF50 fridge. Never went over 4 Amps. I did test it with a high-end Multimeter a well. The result was very similar.
    That 7 Amps stated is over specced on paper in my opinion. They obviously allow for tolerances, as all OEMs does.

    CF 50 test - https://www.youtube.com/watch?v=kCHplnNUi00
    NL 50l Test - https://www.youtube.com/watch?v=pHFRiGo6_xw
    Nice wiring setup there in the vid of the CF-50 and good to know on the 4 Amps.
    I am planning a similar setup.
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