Announcement

Collapse
No announcement yet.

Newbie here, looking for advice on new system

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Newbie here, looking for advice on new system

    Hi all!
    Admin set my permissions right and I'm able to start a thread Hooray!

    I'm new to this forum and into solar systems as well. I am big enthusiast but since I have no experience, I want to setup a small system that will allow me to run a pc/server on solar, so that I get involved and gain some experience in the field. Long (well much much long) term, I would like to go off-grid for my entire home.
    That equipment would draw up to 250W 24/7 when possible. I say when possible because its not the end of the world for me if it shuts down for a few days during the year (1 full day on batteries is ok for me). I live in Athens, Greece and it's sunny most days of the year.
    The tricky parts are that 1.I have a limited budget and 2.the fact that I want to be able to upgrade (till the end of the year possibly) to 350W-400W.
    I have given it a try to design something to meet my needs, don't be too harsh on me that's my first attempt



    So the basic idea is to start with 3 solar panels, 2cc, 6 batteries and a relatively big inverter.
    I chose to go with 3 30A inverters for a couple of reasons. A) because its almost the same price to buy 3x30A or 1x100A, B) if one fails cost of replacing is less than replace a big one, C) I can't afford to go to the full setup at the moment. Fuses are not in the design yet, will add them when I am confident with the basic setup.

    Please let me know what you think, will it work, is it too much, too many components maybe? Your feedback is appreciated!

  • #2
    Why multiple battery banks?
    you sho solar in parallel in mppt but it should be serial. You likely can have three in series.

    you also show inverters connected to charge controllers, it doesn
    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

    Comment


    • #3
      I think I understand what you are saying, I gave it another go:



      Is it better now? Is my plan about adding (later on) a 2nd battery bank in parallel valid?

      Comment


      • #4
        Closer but you do not want 12v modules they are more costly.
        most likely you will have 3 in series but could be 4 depending on your charge controller specs and cold weather
        OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

        Comment


        • #5
          If it is only about cost, I can buy 12V at (almost) the same price for the 24V ones from my supplier.
          But even if I go for the 24V ones, doesn't that mean that I need a charge controller that can handle over 48V (96V for 4 modules in series)?

          Comment


          • #6
            Your battery ah. calculation is wrong. You have 225 ah. @24 volts in the highlighted bank. Series wiring batteries only increases voltage while amp hours remain the same.

            You will be better off output wise if using an MPPT controller and inexpensive 60 cell panels. Any decent MPPT controller will accept 100 Voc. Better ones handle up to 150 volts or more.

            Sounds like you really need to back up and learn the basics before you start designing a system. For example 4, 24 volt panels in series will give you around 180 open circuit volts, not 96 volts as you are thinking. You should read all the stickies in the off grid section of this forum. Get yourself a copy of Solar for Dummies (not a put down, that's just the name of the book) and learn the basics.
            2.2kw Suntech mono, Classic 200, NEW Trace SW4024

            Comment


            • #7
              Originally posted by nkxd View Post
              If it is only about cost, I can buy 12V at (almost) the same price for the 24V ones from my supplier.
              But even if I go for the 24V ones, doesn't that mean that I need a charge controller that can handle over 48V (96V for 4 modules in series)?
              um... you already have 4 PV modules in series for 48V but in reality most 12V PV modules are 18V so thats 72V
              MPPT Charge controllers commonly support 150V and some as high as 600V.

              also at littleHarbor pointed out your Ah calculation is wrong you don't have 900ah/1800ah you have 225ah/450ah at 24V
              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

              Comment


              • #8
                Originally posted by ButchDeal View Post

                um... you already have 4 PV modules in series for 48V but in reality most 12V PV modules are 18V so thats 72V
                .
                With an open circuit voltage of up to 88 volts.
                2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                Comment


                • #9
                  Thanks guys, for pointing these out. I was actually looking to buy a victron charge controller and the 48V / 50 or 65 amps cc's are on the very edge of my budget limit. Am I wasting money going for such equipment?
                  Of course I also need to re-design the battery banks since buying over 30 battery units to reach 2k Ah is not what I was looking for. Or is it inevitable?
                  Going back to research
                  Last edited by nkxd; 01-24-2018, 05:56 PM.

                  Comment


                  • #10
                    Originally posted by nkxd View Post
                    Thanks guys, for pointing these out. I was actually looking to buy a victron charge controller and the 48V / 50 or 65 amps cc's are on the very edge of my budget limit. Am I wasting money going for such equipment?
                    Of course I also need to re-design the battery banks since buying over 30 battery units to reach 2k Ah is not what I was looking for. Or is it inevitable?
                    Going back to research
                    why are you focused on Ah for the battery bank?
                    2000ah at 24V is 48kWh and way way more than a little charge controller or 4 solar panels can charge.


                    OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                    Comment


                    • #11
                      Well, according to this:

                      I need 48kWh to have a 400W output with 2 days of battery only power (in case of bad weather). I can live with 1 day battery support, which would cut this in half.
                      Same calculator also suggests:
                      That 8 x 200W modules would suffice for charge.
                      That I would need a charge controller that can handle 67 amps.

                      Maybe its time to give up on my 2-stage installation idea (1st stage will provide 250W max and stage 2 would climb up to 400W) and set it up for 400W in the first place.
                      I was under the impression that doing so could work as small-scale experiment and if all went smooth proceed to stage 2.

                      I also have another question (in case you aren't bored to death trying to help my sorry ass!) :
                      If I get, lets say 1000W 48V, (that's ~21amps right?) to the MPPT charge controller and the battery bank is 24V, then it will turn them into ~42 amps 24V?
                      If so, then the cc has to be at least 50 amps, is this correct?

                      Comment


                      • #12
                        Using 1 or 2 days of cloudy, will mean your batteries will not last very long, as you will be deeply cycling them. Generally, sizing for 5 days, means only a 20% discharge daily,, giving you long life on the batteries (many shallow cycles)Battery-DoD-vs-Cycles.gif
                        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


                        • #13
                          If you are serious about going off grid you will need to figure out how to reduce your daily loads. 9.6 kwh a day is a big load to try and run off a solar system. You really need to do a load assessment and figure where you can reduce this high demand. Off grid solar will cost you a whole lot more than grid power in most cases. The way it looks here you are going to need a large high kilowatt array, large expensive batteries and large expensive components to run these loads. what you have proposed isn't really expandable to a system the size your loads will require. Not trying to burst your bubble, just stating the facts.
                          2.2kw Suntech mono, Classic 200, NEW Trace SW4024

                          Comment


                          • #14
                            I see your point. It seems I have totally underestimated my load needs.
                            Ok, let's try another approach and see if it is plausible. As I stated my plan was to power a server that is working 24/7 most time of the year. I use this anyway for my job.
                            What if I went off grid only on sufficient sunlight and connect to grid at nights and when its cloudy?
                            This way I can lower my needs significantly. Plus I gain some experience on the field.
                            Would you try something like that? Is there a way to make some calculations and come up with a realistic setup?

                            Comment


                            • #15
                              Originally posted by nkxd View Post
                              I see your point. It seems I have totally underestimated my load needs.
                              Ok, let's try another approach and see if it is plausible. As I stated my plan was to power a server that is working 24/7 most time of the year. I use this anyway for my job.
                              What if I went off grid only on sufficient sunlight and connect to grid at nights and when its cloudy?
                              This way I can lower my needs significantly. Plus I gain some experience on the field.
                              Would you try something like that? Is there a way to make some calculations and come up with a realistic setup?
                              Do you not have a form of net metering?
                              OutBack FP1 w/ CS6P-250P http://bit.ly/1Sg5VNH

                              Comment

                              Working...
                              X