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  • planning for the future

    I've spent about the last six months or so researching green energy ideas particularly PV. I often spent whole days with little sleep trying get a good grasp on the subject. I been practicing soldering cells together and now I'm ready to build my own panel. I have about a hundred cells in excellent condition. They are 6x6 and will generate .6 volts and 8 amps a piece. I'm planning to build a panel of sixty (6x10). I will probably wire them in combination of series and parallel to produce 16 amps at 18 volts for 288 watts. I'm looking for a charge controller but I'm still not sure what will work for me. I plan on having more panels, enough to at least take a big chunk out of my electric bill. So I'm hoping I can buy a controller meant to handle 10 or 12 kilowatts a DAY, later down the road but still be able to work on say 500 watts. I'm interested in an MPPT. Also, some of what I looked at will likely interfere with my tv,(I get HD tv out of the air) radio, and cell phone.
    I'm not afraid to spend a pretty penny on it, I just don't want to have to buy a weaker one to start out with if I don't have to. I buy whatever kinds of batteries in any amount I may need.
    I appreciate any advise I can get and am abundantly grateful for this forum were minds converge.

  • #2
    Building a small panel to learn about solar is a great idea. Building dozens of panels, expecting to reliably run your house from them, is not a winner.

    There are 2 big problems,
    1) home built panels are not UL approved, and if connected to your house, will void your homeowners insurance.
    2) non UL panels will not likely be approved for grid-tie connection.

    Homebuilt is cool for a garden shed, and such, but not a dwelling.
    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
      Mike, sorry if I make people nervous about my project. I have a hard time expressing all of my thoughts about a project without taking up a whole page. I understand the safety concerns surrounding solar power, fires, electrocution, time and energy spent on DIY, as well as insurance issues. Let me clarify my intentions so nobody gets the wrong idea. The panel I am building is just to power a heat lamp and a fan for a chicken coop I am building and for another fan for a greenhouse I built last summer. But I the idea of going green so much that I plan on adding some panels to offset my carbon footprint and pocket some cash down the road. I would never dream of powering my house with DIY panels. It would be naive for someone to think that he or she could solder thousands of cells together sealed up perfectly in a dozen or more panels and expect nothing to go wrong. I own six and a half acres of land which should be enough to put my panels on, I wouldn't even put UL listed panels on my roof never mind DIY, a house fire is too much of a risk especially since I'm not insured. I am looking to buy some UL listed PV panels, but I am inspired to make my own. Although everyone says it's not worth it, I'm a redneck and a jack of all trades, so this is perfect for me. Compared with all the projects I've done, building one 6x10 panel should be no sweat. Also, I just so happen to be close friends with my local friendly building inspector.

      Comment


      • #4
        That's cool, just letting you know what the scoop is. Sunelec.com in Fl often UL listed blems in stock, and some "C" stock with no UL stickers, at good prices.

        Mike
        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
          Thanks for the web address. A lot of their stuff is priced better than most of the on line stores I've seen so far. I'm not sure what sort of equipment I should start out with. I want equipment that can handle the panels I will be getting in a few weeks( probably 3 or 4 hundred watts or so) and still be able to handle much more later on. I just don't want to have to buy more than one charge controller if I can help it. Trying to find one that matches that description is some what confusing.

          Comment


          • #6
            Well, make a guess as to what you need to be "not re-buying" a controller?
            45 amps ? 60amps? 80 amps?

            PWM (basic) MPPT (high efficiency)
            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 just bought two SolarWorld SW 230 Watt Monocrystalline Solar Panels. performance under standard test conditions are... 36.9 Voc, 29.6 Vmpp, 8.42 amps open circuit, 7.76 amps mmp.

              I'm still not sure what to start with for a battery bank but I'd like to try for around 1100 to 1600 amp hours. I cant decide whether to use 12 6 or 4 volt batteries.

              I'm interested in mppt charge controller. I plan on adding more panels. Is there a mppt controller that would be good for much higher watts yet be able to handle what I've got for now? Is there a minimum wattage they can handle?

              Comment


              • #8
                Originally posted by cindynsg View Post
                I just bought two SolarWorld SW 230 Watt Monocrystalline Solar Panels. performance under standard test conditions are... 36.9 Voc, 29.6 Vmpp, 8.42 amps open circuit, 7.76 amps mmp.

                I'm still not sure what to start with for a battery bank but I'd like to try for around 1100 to 1600 amp hours. I cant decide whether to use 12 6 or 4 volt batteries.

                I'm interested in mppt charge controller. I plan on adding more panels. Is there a mppt controller that would be good for much higher watts yet be able to handle what I've got for now? Is there a minimum wattage they can handle?
                What voltage will your battery bank be ? 24V or 48V?

                Batteries need to be (as a rule of guessing) about 10x the amps you have for charge. So if you have 20A for charge, 200A of batteries would be right. If you have backup charging sources, and won't be pulling the batteries down too deeply, you can fudge this some more, but you want to have enough solar amps to be able to equalize the batteries properly. If you get too large of a battery, you will not be able to complete an EQ cycle properly.
                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
                  Originally posted by Mike90250 View Post
                  What voltage will your battery bank be ? 24V or 48V?

                  Batteries need to be (as a rule of guessing) about 10x the amps you have for charge. So if you have 20A for charge, 200A of batteries would be right. If you have backup charging sources, and won't be pulling the batteries down too deeply, you can fudge this some more, but you want to have enough solar amps to be able to equalize the batteries properly. If you get too large of a battery, you will not be able to complete an EQ cycle properly.
                  Are you saying I would need 200 amp hours for the entire battery bank or 200 amps per battery in order to match 20 amps from panels?

                  Arizona wind and sun recomends " 1- 1.5 watts of solar panel power per battery bank amp hours at 12 volts (double that for 24 volts 4x that for 48 volt systems)."

                  Arizona Wind and Sun also says "panels should be 5 - 10 % of battery capacity"

                  Somewhat confusing. Are there simple formulas to follow.

                  Comment


                  • #10
                    10A Charge =
                    x10 = battery amps : 100AH

                    100AH = panels 5%=5AH charge
                    panels 10% = 10AH charge

                    It's all the same. If you don't "know" this, then stick with the larger charge rates, you will also be likely to underestamate your usage. What kills/ruins most battery banks is cronic undercharge, from folks who overeatimate what their panels will put out, and underest what their loads are.
                    Unless you like buying new batteries.

                    Batteries in parallel, ADD the amps from each battery. Volts=same
                    Batteries in series, ADD the VOLTS, and amps stay the same.

                    My 48V array has 8, 6V 390ah batteries. Total array = 48V, 390ah
                    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


                    • #11
                      well, I went to altestore.com and used their method for calculating how many panels I would need.

                      Step 1. Take the number of watts you want to produce in one day and divide it by the insolation value in hours. My insolation value in hours is 4.35 average but as not to underestimate I used 4.15. So 8000 watts / 4.15 = 1927.7

                      Step 2. Allow for normal energy losses and inefficiencies by increasing the number of watts found in step one by 30%. So 1927.7 watts x 30% = 2,506 watts needed to be produced per hour. So I'll buy however many panels it takes to do that.

                      Any problems so far?

                      Then I used Their formula for determining a battery bank size.

                      Step 1. Identify total use in watt hours. 8000 watts per day

                      Step 2. Identify days of autonomy. Multiply watt hours per day by that factor. 8000 watts x 2 days = 16000

                      Step 3. Identify D.o.D. and convert to decimal value. Divide result of step 2 by this value. 16000 / 30% = 53,333.33

                      Step 4. Derate battery bank for ambient temperature effect. Select the multiplier corresponding to the lowest average temperature your batteries will be exposed to. Multiply result from Step 3 by this factor. I chose 50 degrees as not to overestimate and the value they give for that is 1.19. 53,333.33 x 1.19 =63,466 This should be the minimum watt hour capacity of the battery bank.

                      Step 5. Divide result from Step 4 by system voltage. Result is the minimum Amp-hour (Ah) capacity of battery bank. 63,466 / 24 = 2,644

                      Is there a problem with either of these formulas?

                      MY trouble is that after using these formulas my total panel watts don't meet recommendations of other web sites... I should have 3 watts of solar panel power per battery bank amp hours, and or panels should be 5 - 10 % of battery capacity.

                      So is my battery bank too big or is my panel array too small? [B]Which formula should I play with and how is the best way to adjust it?[/B]

                      Comment


                      • #12
                        I use panel amps should be 10% of battery amps
                        1 night = 20% battery discharge
                        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
                          Originally posted by Mike90250 View Post
                          I use panel amps should be 10% of battery amps.
                          If use 11 panels wired in series I will only get about 85 amps, [B]or[/B] do you mean I should divide the 2506 watts from panels by the system voltage(same as battery bank) to convert it to those amps then add onto it?

                          Originally posted by Mike90250 View Post
                          1 night = 20% battery discharge
                          Even if I don't use much at all? Is this 20% due to its own natural discharge with little to no load? I actually do sleep at night.LOL.

                          Comment


                          • #14
                            As you can tell, I am kinda dense when it comes to properly balancing battery bank with panels. I hate to keep asking the same question but I need somewhat more specific answers regarding this topic, because from novice point of view it sounds like you could be saying a few completely different things.

                            Your help in understanding this concept is greatly appreciated.

                            Comment


                            • #15
                              Your panels need to be able to charge and EQ your batteries. That means your PV amps, after the charge controller, need to be about 5-10% of your battery amp capacity. If you have 400AH battery, you need at least 20A (5%) thru 40A of charge, to be assured of de-stratafing the electrolyte in the EQ cycle.

                              You can have more PV, because you may have more daytime loads, loads run off solar, save your battery, they run at 70% efficiency, not 50%.


                              The 20% discharge overnight, means that after 3 days no sun, you will be about 60% discharged, and while that's past the 50% point, it's occasional, and not regular.

                              Your Array of 2506w will only produce 2,000 W under normal conditions, and with a MPPT converter to battery charging volts of 14.5V, yields 140A. So you could go up to a battery bank of 1400AH - but really, with this size of stuff, you should be in series batteries to not have so much parallel connections.
                              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

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