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  • Need help on my first solar build

    Hi, I am new here and new to this all together.
    I have done my googling and searching on the forums and I think I get the basic idea but the calcualtions start to confuse me

    So, here is my plan for my first build and I will go from there.

    Goal: 1000 watts of power for 12 hours per day every day constant power for the full 12 hours and then none for the next.

    I of course am needing to know how many and what size batterys I will need for my bank, I plan to use a durecell 1000 watt inverter for this project ( I already have it), also info on the solar panel itself that I will need would be helpful, I plan on building my own

    I'm dying to see how well all this works and how cheap I can do it for or if I myself can even do it! If all goes well I will invest in better quality higher end equipment and make the system much larger.

  • #2
    This is backwards. You determine your loads, and then build a system to supply that.

    it's like buying a 6 axel truck, when you are moving a box of books. Size the tool to fit the job.

    Also, adding batteries to a used bank, quickly degrades the new batteries to the state of the old ones.

    Many things in solar do not scale well, adding on here & there does not work all the time. 2 more panels, and then you have to get another charge controller, and now you have 2, $250 controllers, when one $350 one could do the job.
    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


    • #3
      I love this, educating folks.

      OK the first step is to determine your daily energy requirement, which it sounds like you have done. So is this correct you want to power a 1000 watt load for 12 hours? OK your daily energy requirement is 1000 watts x 12 hours = 12,000 watt hours. or 12 Kwh.

      Next step is because you want to do this with batteries we need to account for all the losses on a battery system. This adjustment will be used to determine solar panel wattage and battery size required. We take the daily energy load from above and multiply it by 1.5. So 12,000 wh x 1.5 = 18,000 watt hours or 18 Kwh. This means to overcome all the losses your solar panels must generate a minimum of 18 Kwh every day.

      Ok now we are ready to determine the solar panel wattage needed. Since this is a battery system we need to know the worse case solar insolation for your area.. In the USA that would be the months of December and January. So you have to obtain that data specific to your area. You did not specify, so I will make one up but is accurate based on averages of 3 Sun Hours. Your maybe more up to 5 hours if you live in Tuscon, or less if you live up northwest like Seattle.

      OK we know the watt hours needed, and we know the Sun Hours. All we have to do is factor out the time element (hours) to get the wattage needed. So the formula is Solar Panel wattage = Watt Hours / Sun Hours. 18,000 wh / 3 h = 6000 Watts. So for this example using some of your data you will need a 6000 watt solar panel array to get the job done. Getting educational yet? Well the fun has only begun.

      Nest is to determine the battery size in amp hours and a system voltage. With this large of a system you are force to use at least a 48 volt battery voltage or higher. Oops di you buy a 12 volt inverter? Sell it, it will not work. Anyway if you want your batteries to last more than a year you never want to discharge them any more than 20% in any one day. In addition you need extra capacity to carry you through a couple of cloudy days. So we need a 5-day capacity. So we take the adjusted Kwh of 18.000 wh and multiply by 5, 18,000 wh x 5 = 90,000 wh or 90 Kwh. Now we can determine the Amp Hours needed by factoring out the voltage which is the battery voltage of 48 volts. AH = Watt Hours / Battery Voltage, 90,000 wh / 48 volts = 1875 Amp Hours. OK here is where it gets fun, and I mean really fun and educational. You will be using 2 volt batteries, and you will need 24 of them. Each battery weighs 200 pounds for a total weight of 4800 pounds. Total cost just to buy the batteries which does not include shipping is $11,700.

      Now the fun starts since you will have more than 500 pounds of deadly toxic corrosive material (sulfuric acid) on your site, you are going to have to apply for building permits and EPA permits. This means your DIY panel idea just flew out the door. In addition the Fire Marshall will have to get in the act and inspect the site once a year on your nickel to make sure no spills or mis handling of the batteries have occurred. Also you will need a spill containment system for those batteries which cost a pretty penny. Lastly you are going to need around 300/ft2 floor space of reinforced concrete to support and house the batteries.

      OK for a charge controller you will want MPPT types. Sine you will have such a monster sized solar panel array you will have to have two of them rated at 80 amps apiece operating in parallel to handle the 130 amps of charge current.

      Since your inverter will not work on 48 volts, you just as well get one that will actually supply a 1000 watt load at 100% duty cycle. So you will need a 1500 watt inverter operating at 48 volts.

      Wasn
      MSEE, PE

      Comment


      • #4
        [QUOTE=Sunking;9517]I love this, educating folks.
        ....................................
        Wasn
        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


        • #5
          Mike, your first post made no sense to me.

          This is backwards. You determine your loads, and then build a system to supply that.

          it's like buying a 6 axel truck, when you are moving a box of books. Size the tool to fit the job.
          Right...which is what I'm doing, thought I explained that.

          Also, adding batteries to a used bank, quickly degrades the new batteries to the state of the old ones.
          Here is where you really throw me Mike, this information I already knew and I had said absolutely nothing about adding batteries to anything...did ya read the post Mike? Startin to wonder
          Many things in solar do not scale well, adding on here & there does not work all the time. 2 more panels, and then you have to get another charge controller, and now you have 2, $250 controllers, when one $350 one could do the job.
          Here I am going to "assume" your talking about the 1000W inverter I already have...well the 1000w inverter was given to me for free so if I can't use it no loss...its not like I jumped the gun and went and bought garbage I can't use...come on Mike i'm smarter than that

          Sunking:
          Thanks and good info, however your not very good at getting peeps to "want" to do anything like this...pretty much you have helped me decide to completely bomb the idea, delete all favorites related to the whole solar panel thing, and forget it!

          I don't beleave your cost estimate is very correct, but even if it only takes half your estimate its still NO WHERE NEAR worth it for 1000w of juice for 12 hours a day that I can get for $1.30 from the electric company, if the system where 45K to build it would be a waste of my time...beings how at 1.30 for the next 20 years (if the batteries, panels, wiring, racks, ect ect lasted for 20 years...I dought it) thats only $9,360 ... a savings of about 35K according to your estimate by getting it from the power company instead.

          Comment


          • #6
            Originally posted by r6speed View Post
            .... even if it only takes half your estimate its still NO WHERE NEAR worth it for 1000w of juice for 12 hours a day that I can get for $1.30 from the electric company, if the system where 45K to build it would be a waste of my time...beings how at 1.30 for the next 20 years (if the batteries, panels, wiring, racks, ect ect lasted for 20 years...I dought it) thats only $9,360 ... a savings of about 35K according to your estimate by getting it from the power company instead.

            Solar is NOT cheap. The only thing free is the fusion reactor 93 million miles away. parts cost plenty.
            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


            • #7
              I think that everyone has lost themselves in the world when everyone is out for the buck that stays in their pockets, when it realy is all about saving our planet from rape of its offerings that started our lives in the first place. I figure that should be the leaste I could do for being alive on this planet.

              Comment


              • #8
                Originally posted by r6speed View Post
                I don't beleave your cost estimate is very correct, but even if it only takes half your estimate its still NO WHERE NEAR worth it for 1000w of juice for 12 hours a day that I can get for $1.30 from the electric company, if the system where 45K to build it would be a waste of my time...beings how at 1.30 for the next 20 years (if the batteries, panels, wiring, racks, ect ect lasted for 20 years...I dought it) thats only $9,360 ... a savings of about 35K according to your estimate by getting it from the power company instead.
                Well I suggest you price things out and see if I am all that wrong. Here are my numbers

                UL Solar Panels $3 per watt: 6000 wats x $3 = $18,000
                2-85 Amp MPPT Controllers $750 per unit: 2 x $750 = $1500
                Batteries $130 per Kwh: $130 x 90 Kwh = $11,700
                48 Volt 1500 watt True Sine Wave Inverter: $1000
                Misc material wire, battery racks, roof hardware, distribution, etc $5000
                Total $37,200

                That does not include shipment, permits, labor, and inspection fees. Now you might be able to get better prices because I am quoting quality products like BP or Kyocera panels, Surrette batteries, and Xantrex charge controllers and inverters.

                Another error I see is you assumed the batteries will last 20 years, they will not. If sized as specified you will get 5 to 7 years out of them before having to replace them at even higher cost 5 to 7 years from now.


                You are correct about the payback or ROI, there is none when you want to go off grid. Going off-grid means you will be paying 10 to 30 times more than buying it from the utility. That was the educational part of this lesson.

                Here is your example: Your system will generate 12 Kwh per day, 366 Kwh per month, 4392 Kwh per year, and 21,960 in 5 years when the batteries need replaced. Using my parts estimate that works out to $37,200 / 21,960 Kwh = $1.70 per Kwh. What do you pay for a Kwh? 10 to 13 cents? That is the Fun Part
                MSEE, PE

                Comment


                • #9
                  Originally posted by BuzzBuds View Post
                  I think that everyone has lost themselves in the world when everyone is out for the buck that stays in their pockets, when it realy is all about saving our planet from rape of its offerings that started our lives in the first place. I figure that should be the leaste I could do for being alive on this planet.
                  Sounds like greenpeace, the EDF or one of 'those' organizations propoganda. The idea is to use your money where it does you the most good. Not to piss it away on 'neat' sounding concepts and things.

                  When green ideas have some sound science, economics and engineering behind them they manage to get a lot farther than the airy-fairy garbage you see on many green sites.
                  [SIGPIC][/SIGPIC]

                  Comment


                  • #10
                    I agree with you was just having a laugh thats all

                    Comment


                    • #11
                      Sunking:
                      Thanks, I appriciate all the info and it has definately made me realize I would rather not get into this, as I am more "investment" orientated, I didn't say the batteries would last 20 years...I said IF they lasted 20 years, and I dought it.
                      Yup its confirmed this WILL NOT save you $ nor be a good investment unless its an investment in your planet, I will not be participating.
                      Thanks guys!

                      Comment


                      • #12
                        Originally posted by r6speed View Post
                        Yup its confirmed this WILL NOT save you $ nor be a good investment unless its an investment in your planet,
                        I will not be participating.
                        BUT, all these make us think and try hard to find out alternatives.
                        Sun warms the seas, make cloud, then rain then fills lakes, then makes flow creates energies.
                        Then, sun energize panels, makes water pumps lifting waters, makes water turbines creates energy.

                        Comment


                        • #13
                          Wow! This post as I see it, has only managed to discourage people from going green as if it cannot be obtained. I have done much reasarch perhaps not as much as sunkings but [I think] the best method of using solar is to sell it back to the electric company thru a grid tie system. No batteries are required for this and you can have seperate panels running the 15- 20 amps of outlets thru out the house to lower the cost of your bill and run the grid tie during the day pushing electriciy back to the company creating for you the opportunity to pay very minimal if any cost per month.
                          I had a change of heart about going solar because I had an eye opening debate with someone and he won! LOL!!

                          I wouldn't leave it altogether though, only use is it for charging up battery operated tools or to light up a shed or if I am going camping. I think solar panels are cool to have but not to run an entire house, it's not worth the money!

                          Comment


                          • #14
                            Spam

                            @Pennyguy - still dropping the spam I see - you are apparently dedicated to getting your hits at the expense of everyone else.
                            [SIGPIC][/SIGPIC]

                            Comment


                            • #15
                              Just experimenting! Are you the sites police? LOL!!!!
                              I had a change of heart about going solar because I had an eye opening debate with someone and he won! LOL!!

                              I wouldn't leave it altogether though, only use is it for charging up battery operated tools or to light up a shed or if I am going camping. I think solar panels are cool to have but not to run an entire house, it's not worth the money!

                              Comment

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