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  • can i use a solar panel without using battery

    My question is
    can i use a solar panel in daytime directly to supply electricity my home appliances without using battery.

    i mean

    one solar panel and then inverter and then load.

    is it possible?
    what possible safety measure should i have take into account to protect my appliances from overcurrent.

  • #2
    If you're planning an off-grid system,it wont work. The inverter input has to be within a certain range ,and the panel voltage is above that range during most of the day.

    Comment


    • #3
      No it will not work.
      MSEE, PE

      Comment


      • #4
        Are you trying to describe a "grid tie system" where a very special type of inverter takes power from a string of PV panels, and feeds that into the grid? In that case, the grid acts as the battery.

        Somewhere, you need a battery, either the "grid" or a bank of batteries.

        Panel and load only works for some special water pumps with expensive control modules.
        spreadsheet based voltage drop calculator:
        http://www.solar-guppy.com/download/...calculator.zip
        http://www.solarpaneltalk.com/showth...oss-calculator

        http://www.mike-burgess.org/PVinfo_2.html

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister ,
        battery lugs http://tinyurl.com/LMR-BigLug
        Setting up batteries http://tinyurl.com/LMR-NiFe

        gear :
        Powerfab top of pole PV mount | 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

        Comment


        • #5
          This was one of my main questions I wanted to ask before I start buying equipment. And it will be off grid.

          With the EXTREMELY high price of batteries now, which from my research, now way surpasses the cost of panels factoring in life of product, it doesn't seem logical to have a large battery bank if the majority of electrical use will be during sunlight. I will still have batteries, but I was thinking something like 2 6v 390Ah batteries for minor use after sundown.

          Figuring you sleep 6-8 hours at night and here in Arizona you've got say, at least 9-12 hours of sunlight a day. And I don't understand why people wouldn't put some panels on a "fairly simple" pole mount which can be moved by motor or hand. Wouldn't you then get pretty much the full amount of "sun power" sun up to sun down?

          That being said, there must be a way to pretty much bypass the batteries during the day, instead of spending thousands of dollars on batteries. Seems like an awful waste to have to use the batteries as a go between, unless it doesn't affect their life, which leads me to another question. Does it? When you have say 1000 watts of sun power and you use less than that at any given time while the panels are producing that, does the power just kinda pass through the battery without degrading life?

          Comment


          • #6
            The thickness of the soup we call "atmosphere" really does block a lot of power from the sun in the dawn-10am, and 3pm - sunset. The 4 hours around noon[+2,-2], are the productive ones, so an "ultra tracker" won't help much outside those hours.

            You don't "bypass" batteries in the daytime, you have to recharge them, and then, use "opportunity" loads in the afternoon, after the batteries have begun the absorb part of the cycle, and you have some spare PV to run the washer and maybe air conditioner.

            If you feel you can get by with only small loads at night, great. I won't tell you to spend $ needlessly, but if you discharge batteries too deeply, you shorten their lifetimes.
            Attached Files
            spreadsheet based voltage drop calculator:
            http://www.solar-guppy.com/download/...calculator.zip
            http://www.solarpaneltalk.com/showth...oss-calculator

            http://www.mike-burgess.org/PVinfo_2.html

            solar: http://tinyurl.com/LMR-Solar
            gen: http://tinyurl.com/LMR-Lister ,
            battery lugs http://tinyurl.com/LMR-BigLug
            Setting up batteries http://tinyurl.com/LMR-NiFe

            gear :
            Powerfab top of pole PV mount | 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

            Comment


            • #7
              So, again if you have fully charged batteries and say you have 1000 watts of panels capable of producing that and you start using 7 100 watt light bulbs, does the power come from the batteries or pretty much straight from the panels? In that scenario, which I think for me would be typical of most daylight hours, would the power usage affect battery life?

              And I know my knowledge with all this is very basic and beginning, but I just took out my 30 watt panel and did some tests.

              Directly aimed at the sun, it was at about 24v and .95A. Set on a flat surface, it was 1-2 volts less but the current was .35.
              That was measured at 4:30pm Arizona time. Am I wrong to assume that could be 3 to 1 power difference?

              From what I know so far, I can't tell the watt output until I put a load on it and bring it down to 12v then do the measurements, right? And any easy way of doing that?

              Oh, I just looked up the specs, for my uni-pac 30, and the short circuit specs were 2.1A, which is what it was when I measured it a month or so ago at high noon. So, does that mean it would put out about 15watts when I measured it facing the sun 20 minutes ago?

              Comment


              • #8
                Originally posted by themaxx69 View Post
                So, again if you have fully charged batteries and say you have 1000 watts of panels capable of producing that and you start using 7 100 watt light bulbs, does the power come from the batteries or pretty much straight from the panels? In that scenario, which I think for me would be typical of most daylight hours, would the power usage affect battery life?
                Why would you burn 7 light bulbs in the day time ?

                What you haven't picked up on is the batteries, or the grid, level out the power supply.

                Panels don't produce a nice, even steady flow of electricity like a generator does ( heck, even they bog down when you load them up )....a fixed panel produces a little at sunrise, then the most around noon, then tapers off again in the afternoon as the sun angle falls away from perpendicular to the face of the panel. Also, weather conditions GREATLY affect the output. Cloud moves over, output falls WAY off.

                In the case of incandescent light bulbs, say a cloud moves overhead.....they would simply dim. But what happens if you're using a motor ? Brown out....or your system tries it's best to pull it out of the small battery bank.

                In a IDEAL world, your attempt "might" work....if you could sit there all day and match your power use to the output of the panels every given second ( or maybe split second )....but I know I sure don't have time to do that......so I pull my excess needs ( wife flips on the oven, or the dryer, or a hair dryer, or anyone of a dozen other things ) from the grid, if the grid is up, and from my batteries ( on limited circuits.....she's just flat out of luck with the oven or the dryer....ahahahaaa ) if the grid is down.

                Then, when we have excess power the house is NOT using, the meter turns backwards as we put it back on the grid. In off grid situations, if the battery was fully charged, and you weren't using the full power the panels produce, power simply wouldn't BE produced.....the panels just sit there at idle until a load occurs.

                That's the WHY of what these other guys are trying to tell you when they say "It won't work"......because it won't work.

                Comment


                • #9
                  Originally posted by TnAndy View Post
                  Why would you burn 7 light bulbs in the day time ?

                  What you haven't picked up on is the batteries, or the grid, level out the power supply.

                  Panels don't produce a nice, even steady flow of electricity like a generator does ( heck, even they bog down when you load them up )....a fixed panel produces a little at sunrise, then the most around noon, then tapers off again in the afternoon as the sun angle falls away from perpendicular to the face of the panel. Also, weather conditions GREATLY affect the output. Cloud moves over, output falls WAY off.

                  In the case of incandescent light bulbs, say a cloud moves overhead.....they would simply dim. But what happens if you're using a motor ? Brown out....or your system tries it's best to pull it out of the small battery bank.

                  In a IDEAL world, your attempt "might" work....if you could sit there all day and match your power use to the output of the panels every given second ( or maybe split second )....but I know I sure don't have time to do that......so I pull my excess needs ( wife flips on the oven, or the dryer, or a hair dryer, or anyone of a dozen other things ) from the grid, if the grid is up, and from my batteries ( on limited circuits.....she's just flat out of luck with the oven or the dryer....ahahahaaa ) if the grid is down.

                  Then, when we have excess power the house is NOT using, the meter turns backwards as we put it back on the grid. In off grid situations, if the battery was fully charged, and you weren't using the full power the panels produce, power simply wouldn't BE produced.....the panels just sit there at idle until a load occurs.

                  That's the WHY of what these other guys are trying to tell you when they say "It won't work"......because it won't work.
                  Thank you for that intelligent and well worded answer
                  Rich
                  WWW.solarsaves.net

                  NABCEP certified Technical Sales Professional

                  http://www.solarpaneltalk.com/showth...Battery-Design

                  http://www.calculator.net/voltage-drop-calculator.html (Voltage drop Calculator among others)

                  www.gaisma.com

                  Comment


                  • #10
                    panel output verses time of day

                    Here is an attached "bell curve" of an imaginary 120w panel and its aprox outputs over the daylight hours.. Obviously it wont be exact for every location ,its just to give an idea even though there is "daylight" its not not enough to produce much power except for a comparatavly short period of the day
                    Attached Files

                    Comment


                    • #11
                      Originally posted by TnAndy View Post
                      Then, when we have excess power the house is NOT using, the meter turns backwards as we put it back on the grid. In off grid situations, if the battery was fully charged, and you weren't using the full power the panels produce, power simply wouldn't BE produced.....the panels just sit there at idle until a load occurs.

                      That's the WHY of what these other guys are trying to tell you when they say "It won't work"......because it won't work.
                      Ok, I REALLY appreciate the info, but no one is answering the question I asked twice now, I think.

                      The quote above looks like half an answer, but not fully.

                      Again, I mainly want to know how the system works beginning with the electricity produced at the panel and ending with whatever is using it. And all this has to do with how the battery life is affected.

                      I thought I laid it out pretty easy and precise.

                      If you have fully charged batteries and say you have 1000 watts of panels capable of producing that, meaning the sun is directly over head and at maximum strength and you start using 5 100 watt light bulbs,which equals 500 watts, does the power come from the batteries or pretty much straight from the panels? In that scenario, which I think for me would be typical of most daylight hours, would the power usage affect battery life? Is the power to lights coming from the batteries stored energy then immediately recharged or what. Or is the power coming from the panel and kind of passing right through the battery to the device using it. And again I'm talking about a device requiring LESS power than the array is capable of producing at that given time.

                      This is what I would like cleared up, seems such an easy question. I honestly think this is a real basic, fundamental question because battery cost is MUCH MUCH more expensive if you factor in average life spans. Common sense tells me, "basically" the electricity would flow straight through the system, in this case.

                      I really would just like a straight answer or at least tell me I'm dumb and point me in the right direction of where to find the answer if it's somehow super complicated to explain.

                      Comment


                      • #12
                        It is not complicated at all. If the panels generate equal or more power than is demanded it goes to the load. If not the batteries have to make up the shortage. It is simple math where both sides of the equation have to be equal and true.
                        MSEE, PE

                        Comment


                        • #13
                          Originally posted by Sunking View Post
                          It is not complicated at all. If the panels generate equal or more power than is demanded it goes to the load. If not the batteries have to make up the shortage. It is simple math where both sides of the equation have to be equal and true.
                          ALRIGHT! That's what I was looking for....I think. So as long as the demanded load doesn't exceed what the panels can provide, the batteries power isn't used? And then it doesn't affect the batteries at all. So for ****s and giggles, If you never exceeded the panels production, would the battery last forever or more than 10 years? The highest Trojan's graph goes is 5000 cycles I think.

                          Comment


                          • #14
                            Or should I just say screw it and try to find a used HUP Solar-One battery.

                            Comment


                            • #15
                              Originally posted by themaxx69 View Post
                              ALRIGHT! That's what I was looking for....I think. So as long as the demanded load doesn't exceed what the panels can provide, the batteries power isn't used? And then it doesn't affect the batteries at all. So for ****s and giggles
                              I did not say that. That is only true assuming the batteries are fully charged.

                              Here is some math fun. Current out from the controller is 60 amps, batteries are charging with 30 amps. What is going on?
                              MSEE, PE

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