Announcement

Collapse
No announcement yet.

can i use a solar panel without using battery

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

  • #31
    Originally posted by themaxx69 View Post
    That answers some of my questions. And gives me more to think about.

    May be this should have been my first question, can I have an off-grid PV system with no batteries. 100% of electrical needs will be covered by the panels.
    Nope. The sun is too variable, and you would have to "overbuild" the system to run the 200w fridge, by nearly 150%, to supply starting surge, and capacity to keep it running while a cloud, haze, airplane shadow, or anything that affects the brightness of the sun. Otherwise, your gear will only run for about an hour per day (at solar noon)
    5-13Chart.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


    • #32
      For what I want, that graph looks pretty good to me. Even though with my initial findings, I still think panels on a tracker provide more energy earlier and later. That I will need more time and more measurements.

      But simply looking at that graph, why would I need batteries if my power usage fell within those parameters?

      Comment


      • #33
        Originally posted by themaxx69 View Post
        ...But simply looking at that graph, why would I need batteries if my power usage fell within those parameters?
        That graph is in minute increments. See all the spikes on the left side, That's the power you can use, if you have a 4.5KW array (which is what the graph came off) The starting surge of everything, has to stay below the red line at all times.

        Or just try it, and see what happens. Things may work ok for a while.
        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


        • #34
          Think this would be enough to not need batteries!

          my house.JPG

          Comment


          • #35
            Originally posted by themaxx69 View Post
            Think this would be enough to not need batteries!
            Nope - they have the grid to serve as a battery
            [SIGPIC][/SIGPIC]

            Comment


            • #36
              So, you're all telling me that if I want to run my 300 watt fridge during the "daylight" and I have 1000watts of solar panels, I can't use that to run my fridge with no battery in between? Off-grid.

              Comment


              • #37
                Originally posted by themaxx69 View Post
                So, you're all telling me that if I want to run my 300 watt fridge during the "daylight" and I have 1000watts of solar panels, I can't use that to run my fridge with no battery in between? Off-grid.
                Max you just do not understand the simple math problem I told you earlier. For a stand alone system, meaning batteries only, the energy from the panels has to have a place to go. Where that energy goes depends upon demand by the batteries state of charge, and the connected equipment load.

                It can be 12 noon with bright sun, if the batteries are fully charged and no load demand by the equipment there is no power from the panels going anywhere. It is just not being used and all that potential energy is completely wasted..

                If at 12 noon the batteries are discharged, and no equipment load, then current will flow to the bateries based upon the state of charge of the batteries.

                But to answer your question you cannot do what you want to do. With a stand alone system you have to have batteries period. Thios batteries have to be sized at least 8 to 10 times larger the the charge current. If not you will burn them up. So if you are ignorant enough to run 5000 panel watts into 12 volt batteries will produce a maximum charge current of 5000 watts / 12 volts = 416 amps. That means you will need 10 x 416 amps = 4160 Amp Hour batteries. Put another way a battery that weighs 2700 pounds.

                Change it to 24 or 48 volts same answer it takes a 2700 pound battery. Otherwise it goes BOOM! That is all you need to know for now.
                MSEE, PE

                Comment


                • #38
                  Big arse capacitor

                  Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.

                  Just as a hobby interest:
                  Probably not scaleable: i took a fairly large (free) cap bank used in place of batteries and use it to power my regular ac lights in my mostly underground basement while working during the day.

                  Solar panel to MMPT charger/controller to cap bank to dc to ac inverter to outside inlet plug into basement.

                  Not recommending this to anyone-please do not do this at home- just keeping the discussion going to maybe explore other non-battery ways to use the sun's energy.

                  Comment


                  • #39
                    Originally posted by BeRight View Post
                    Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.
                    Well you bring up a valid point that demands an explanation.

                    Batteries and capacitors are very similar devices but work and behave quite differently.
                    • Batteries use chemical energy to store energy, and a capacitor stores it in a electrostatic field just like static electricity.
                    • Battery terminal voltage is very constant and stable while being charged and discharged. Capacitors voltage varies constantly from 0 volts at 0 charge to its specified terminal voltage. For example lets say you charge a capacitor up to 12 volts. When you discharge it 25% the voltage falls to 6 volts, and at 50% falls to 3 volts.
                    • A battery take time to charge and discharge, a capacitor can be fully charged in less than a second and discharged just as fast.
                    • A battery can hold a charge for a very long time, a capacitor cannot.
                    • But now here is the kicker. A battery can store a massive amounts of energy for a given volume compared to a capacitor. So those caps you say that provide energy can only do so for second or two depending on the size and rate of discharge.
                    MSEE, PE

                    Comment


                    • #40
                      ultracap

                      In using ultracaps - i find just the opposite of what one might think (different technology)-discharge is slow.

                      The challenges: slow to charge and dc to ac converters cut out close to 10V. So, yes one needs to keep lots of Amps coming in to keep them charged. The 2600F ultra cap I am using is really small and light(compared to caps of the past)__ lots of folks doing work to shorten charge time. Their usefulness for real time use of solar power might not be very far away.

                      In my early stages of playing with these I hooked up eight, charged - connected cheap dc to ac inverter and powered my 42" LCD, and watched TV for 7 minutes. And of course I am having very good results in using ac CFL lighting.

                      I plan to keep playing and designing circuits around them for the ultimate advantage of never having to worry about number of charge cycles-they sound last a long time. I have found however that i do have to address balance of charge when connecting in series and parallel.

                      Just my $.02

                      Comment


                      • #41
                        Originally posted by BeRight View Post
                        Just brainstorming here_so go easy_issue is storing energy for a short period of time since he seems to want to only power things while he can get solar energy_capacitors can store energy for a little while.

                        Just as a hobby interest:
                        Probably not scaleable: i took a fairly large (free) cap bank used in place of batteries and use it to power my regular ac lights in my mostly underground basement while working during the day.

                        Solar panel to MMPT charger/controller to cap bank to dc to ac inverter to outside inlet plug into basement.

                        Not recommending this to anyone-please do not do this at home- just keeping the discussion going to maybe explore other non-battery ways to use the sun's energy.
                        Not only not recommended for others but a bit dangerous for most anyone -
                        [SIGPIC][/SIGPIC]

                        Comment


                        • #42
                          youtube video on ultracaps

                          checkout you tube: just type in ultra caps- one video shows the power of one ultra cap 2600F the guy is holding the leads attached to each end of the cap and basically is doing arc welding with it.

                          I agree: extreme care must be taken when working with high energy devices which includes batteries!

                          Comment


                          • #43
                            Originally posted by BeRight View Post
                            checkout you tube: just type in ultra caps- one video shows the power of one ultra cap 2600F the guy is holding the leads attached to each end of the cap and basically is doing arc welding with it.

                            I agree: extreme care must be taken when working with high energy devices which includes batteries!
                            Readers should not confuse ultra capacitors with batteries nor the dangers of either.

                            The ultra cap energy storage for common household use thingy is one of the current loony green items - going to save the world etc - which is all a bunch of BS

                            Charged batteries should always be treated with caution and respect.
                            [SIGPIC][/SIGPIC]

                            Comment


                            • #44
                              Apologies

                              My apologies to all for my diversions and discussing some of my strange/stupid hobbies on this forum.

                              Comment


                              • #45
                                Originally posted by BeRight View Post
                                I plan to keep playing and designing circuits around them for the ultimate advantage of never having to worry about number of charge cycles-they sound last a long time. I have found however that i do have to address balance of charge when connecting in series and parallel.
                                Well you might want to do some homework on capacitors. When you connect 2 two of them in series of equal value, you cut the capacitance in half. For example 2-1000 ufd in series = 500 ufd. You are shooting yourself in the foot.
                                MSEE, PE

                                Comment

                                Working...
                                X