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  • Advice on what I should do next

    So I've been off grid since the beginning of summer and decided it was time for some power now that the days are getting shorter. I didn't want to jump right in and get a large professionally installed system as I would rather play around with a smaller system to gain some experience, learn how things work, learn how to take care of batteries that kind of stuff. So right now I'm still kind of piecing a system together although I have finally started producing power. I currently have 400 watts of panels, a PWM 40A CC and 2 6v golf cart batteries @ 12v 215AH and so far it's been working fine for the few lights I've been running at night. I would like to expand some with the goal of being able to run a little more than just some lights. I'm thinking I'd like to add another 100 watt panel and 2 more batteries at which point I might as well jump up to a 24v system. I'm currently running lights off the load output and no inverter yet but was planning on no larger than 1000w and battery wire size is 2 gauge.

    Will 500 watts support a 24v 430AH battery during winter?
    How do I go from 24v down to 12v to run lights?
    Do you see any problems?


  • #2
    It is hard to answer your question without first you telling us what you need in daily watt hours. Just saying a few lights do not give us enough to tell you.

    I will say that using a PWM CC will lose about 33% of the total wattage of your panels for charging. I will also say that for a 430Ah battery you will need about 43 amps of charging. So that means a new 60 amp MPPT CC along with about 1000watts of panels.

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    • #3
      I've read many times you need to figure out your load and size your system from there. I took the exact opposite approach. I moved in to my cabin and spent the year (somewhat) without any electric to see just how much I could live without. Most items I could just charge while driving. The only time I really fired up the generator was to run a fan in the window at night to cool the place off and that was for about a month during the summer. So my power needs are minimal. At most it would be nice to run a small dorm sized fridge.

      I'm aware I would be better off with a MPPT CC and had planned on upgrading at some point probably once another pair of batteries were added.

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      • #4
        The problem is if you just add batteries without knowing your watt hour needs you may just end up throwing away a bunch of money until you get the right combination of panels, CC and batteries.

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        • #5
          Originally posted by SlurpJ View Post
          I've read many times you need to figure out your load and size your system from there. I took the exact opposite approach. I moved in to my cabin and spent the year (somewhat) without any electric to see just how much I could live without. Most items I could just charge while driving. The only time I really fired up the generator was to run a fan in the window at night to cool the place off and that was for about a month during the summer. So my power needs are minimal. At most it would be nice to run a small dorm sized fridge.

          I'm aware I would be better off with a MPPT CC and had planned on upgrading at some point probably once another pair of batteries were added.
          Do what you want but know that your approach as described would be different than that of knowledgeable folks. Size and design your equipment to the expected loads and your goals.
          You will wind up with a better, more fit for purpose system.

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          • #6
            Most dorm fridges are energy hogs with thin insulation and low quality motors. A 22CF energy star fridge is likely only going to consume about 1kwh daily, but any fridge will need about a 1,000 watt inverter to supply the starting surge for the motor.
            Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
            || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
            || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

            solar: http://tinyurl.com/LMR-Solar
            gen: http://tinyurl.com/LMR-Lister

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            • #7
              Alright so obviously I need to slow down here, sorry about that I'm still building my place so I'm constantly thinking 3 steps ahead. Also still learning and researching. Like a fridge for example. Still looking into what the most efficient option would be whether that's a dorm sized fridge, a 12v fridge or a converted chest freezer. And since I'm getting by just fine with what I have now I should probably slow down and just learn to properly use and care for what I currently have. So simple question and I think I know the answer already but want to verify with the pro's, what should my batteries be reading when fully charged?

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              • #8
                Lead acid battery voltage chart

                battery-state-of-charge2.jpg
                Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                solar: http://tinyurl.com/LMR-Solar
                gen: http://tinyurl.com/LMR-Lister

                Comment


                • #9
                  Thank you, I had actually found a similar chart as well. This ones all nice and color coded so I'll print it and hang it for quick reference. I've been monitoring voltages and so far I have yet to get below 80% closer to 90% actually, measured with a volt meter at the battery.

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