Announcement

Collapse
No announcement yet.

Utilizing excess energy from solar panlel - not a dumpload question ;-)

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

  • #31
    Nice small detail on these to screenshot.

    Float level and still high output from the solar panels.

    Only difference between them: A load of 200W via a Victron inverter, still manually remotely applied thought ;-(



    TriStar MPPT - Live Data (1).JPGTriStar MPPT - Live Data.JPG
    --------------------
    Norwegian off grid cabin owner
    Panels facing south

    - Kyocera panels 135W
    - Tristar 60A MPPT
    - Victron 3000w/12V / 120A

    Comment


    • #32
      Originally posted by Olberg View Post
      [ATTACH=CONFIG]2808[/ATTACH]Stu: Fantastic with web monitoring like that. Something I certainly will look into after I’ve installed my system.

      Stu, Inetdog and Roli:


      Am I thinking totaly bonkers or could perhaps the solid state relay Stu’s using (lika a HDD-06V75) be controlled directly with PWM (analog pin) from the arduino?


      /O
      No problem from what I know. The challenge is knowing how to determine the PWM rate. The Outback takes care of this, insuring the Absorb and Float are always maintained at proper voltage. From watching my system in action, I can say that this is a constantly adjusting real time effort as I watch the PWM rate vary on the display of the Outback. You could replicate this of course with the Arduino by watching the voltage at the battery during these charge cycles and increasing the PWM rate until voltage drops then back off until it returns. Feels like some complicated programming though to insure you don't start creating some crazy feedback loops! Think about a cloud passing in front of the sun for a second and imagining how you would accomodate this in real time without compromising the charging voltages.

      Comment


      • #33
        Here is a reply from the manufacture on the subject:

        "When used with a PWM control, the Power-io will act in a similar fashion to a variable switch. For example, if connected to a visible light bulb, at a very low PWM speed, you will see rapid ONs and OFFs. If connected to a heater, these ONs and OFFs determine the amount of heat rise, such as you have inside an electric oven in your house.

        At higher PWM, you eye will not see the light bulb go on/off/on/off. You will see the average light, even though the bulb is actually going on/off/on/off rapidly. Your eye is only accurate up to about 100 Hz. (An AC lightbulb in your country is probably running at 50 Hz, but we consider that 100 Hz switching since there are 100 half cycles in a 50 Hz power line.)

        Our product can go on/off/on/off up to about 15-20kHz speed. Our maximum speed is obtained with a strong control signal.

        Your Arduino is a medium strength control signal. At about 5V, 40mA, you will be able to PWM us at about:
        50 microseconds ON, 80 microseconds to remain ON, then OFF. Thus, you will be able to reach a maximum speed of about 1-2 kHz, which is still incredibly fast.

        Power-io is often used with solar applications. I have been told that we are part of an interesting system in the Antarctic.

        Your attached PWM chart is accurate. First, you determine your overall PWM speed (above) then the Arduino determines how much of that cycle will be an ON and how much will be an OFF."

        Stu:
        Yes. Programming it will be a challenge!
        It must be in real time. I will have to continuously read the Canbus. Use the incoming PV current from the cc and read the battery voltage and current.
        Pv current (recounted to match read battery voltage) - Battery current + current to the SSR( opportunity current) = 0 is my theory.

        /O

        Comment


        • #34
          heater

          Why can not the man put his heater on full 500W and then let all the dump or extra load go directly from the panels to the heater? Ok this would probably make the heater jump in all directions (hotter and lower) but it would not explode?

          Comment


          • #35
            Originally posted by rainworm View Post
            Why can not the man put his heater on full 500W and then let all the dump or extra load go directly from the panels to the heater? Ok this would probably make the heater jump in all directions (hotter and lower) but it would not explode?
            Heater is 220V AC, but even if it would have been a AC 12V heater the Tristar MPPT need a battery as powersource, and can not be replayced by a load like a heatr
            --------------------
            Norwegian off grid cabin owner
            Panels facing south

            - Kyocera panels 135W
            - Tristar 60A MPPT
            - Victron 3000w/12V / 120A

            Comment


            • #36
              To the question of accuracy and milliseconds - is it necessary to be so spot on?

              How about the following.

              The Arduino pays attention to the status of the controller:
              - Charge state: Bulk, Absorption and float
              - Battery voltage
              - Watt to the batteries (or Amps)

              As a test case we can set the following equipment:
              1000W of solar panels
              1000W of load (Heater) (proportionaly adjustable - maybe as a DC consumer via a inverter)
              12V battery - but let's focus on watt and watt hours and not volt amps (yeah I know should have been 24V)


              When in bulk - Do nothing

              When in Absorption pay attention to Watt every 5 min, the start watt in absorption mode indicates available solar energy at this time (and should probably stored as value) but of course if could rapidly change in both directions), when watt has been reduced with let say 50W, turn on the heater and apply 10% ( of the 500W example load) and measure watt again. If Watt into the batteries has increased with 50W then we now the sun has been able to cope with the additional load. This last parts should then be a loop, and could run every 5 min and adjust up and down accordingly.

              While in absorption mode the natural max load will probably be in the area of 90% of the solar panel max power.

              In an increase in load make the regulator move back to bulk, we now we have applied to much load, and can adjust it.

              I guess my main idea here is to allow the load to be both "too low" and "too high", allowing some energy to be wasted, and some energy to be drawn from the battery bank.
              --------------------
              Norwegian off grid cabin owner
              Panels facing south

              - Kyocera panels 135W
              - Tristar 60A MPPT
              - Victron 3000w/12V / 120A

              Comment


              • #37
                Originally posted by rainworm View Post
                Why can not the man put his heater on full 500W and then let all the dump or extra load go directly from the panels to the heater? Ok this would probably make the heater jump in all directions (hotter and lower) but it would not explode?
                Since the batteries are still going to need a float charge available continuously, you would have to figure out how to send some of the panel output to the controlller, and some to the heater. And it would be changing in real time. Not to mention the Absorb stage opportunity would be missed. I had considered taking this approach at one time, but now that I see how hard the Outback seems to be working to maintain the right voltages to battery I am glad I left this control in the hands of the professionals haha!

                Comment


                • #38
                  Originally posted by inetdog View Post
                  Some people in this and other forums make a distinction between a dump load, considered as a place to either use OR waste power to prevent overcharging of a battery bank or to keep a load on a wind or hydro turbine to keep it from running out of control when no power is actually needed. For wind, hydro, or shunt type battery charger, this load is not optional it is required.

                  When the specific goal is to take available power that would otherwise be wasted, as for example, the extra PV potential output when an MPPT controller does not need to use full output, it is more often called an opportunity load. It is completely optional in that if it is turned off or disconnected, nothing bad will happen to the system.

                  The most common opportunity load is water heating. This can be done directly with DC from the power source, but that requires finding heating elements with non-standard voltage and resistance specifications to make best use of the power. A few people have put forward the idea that as long as you have an inverter running off the batteries anyway, you can just as well power your opportunity load from the inverter whenever the battery bank is fully charged. The input current to the inverter will simply come directly from the panels rather than forcing a charging and discharging of the batteries.

                  The simplest way to control this is to use an output from the CC which indicates that it is in Float to drive a relay which energizes the heating element. That will not let you use surplus power during Absorb. That would be more complicated.

                  An idea which I have not seen explored would be to take off the excess power before the MPPT CC by sensing the current being drawn from the panels by the CC and pulling additional current into an opportunity load when the CC current is below the current Imp value. But that would require some way of knowing how much light is hitting the panels, or at least what the current Imp value is.
                  And too rapid a response could cause instability in the MPPT algorithm of the CC.
                  Originally posted by inetdog View Post
                  If you do a google search for power management systems, you will eventually find a company that sells something to the UK market that regulates the opportunity load to exactly null out any power returned to the grid in a grid tie system. The only reason this makes sense it that the UK tarifs pay the user more for each KwH generated and used on the premises than for the same amount of power generated and returned to the grid. So the concept is around, just not apparently in the context of off-grid.
                  At some point the extra complexity and risk of failure is not justified by the energy saved. Also, it requires the CC and the inverter to be closely coordinated.

                  The problem with a resistive load, of course, is that it has a fixed rather than a variable resistance. So you have to either control the voltage applied to it or switch the load on and off in multiple segments. The best way to deliver a variable power to a resistive load is via a DC-to-DC converter or an inverter combined with an SCR type current regulator.

                  And, no a simple diode network cannot do this since the CC needs to be able to draw power back from the battery at all times and sense the battery voltage, while the inverter needs to see constant power or trip out from low battery voltage or overload on its output.
                  I have a similar need in Ga. GTI. NO COMPSATION for excess generation, so retaining generation to use in load is very important. Other wise a loss

                  Comment


                  • #39
                    Originally posted by solga View Post
                    I have a similar need in Ga. GTI. NO COMPSATION for excess generation, so retaining generation to use in load is very important. Other wise a loss
                    But if the uncompensated power back to POCO does not cost you anything to generate, it is not a LOSS. It is an unrealized income.
                    It is a good reason not to oversize your system, but unless you have opportunity loads that you can turn on for local use, such as water heating, to keep your production at maximum, there is no point in throttling back your output to avoid giving away power.
                    And any expense for systems to avoid that sad state of affairs would truly be wasted, since they would not save you anything.
                    Throttling systems make sense where you are not allowed to feed energy back into the grid, less to when you just are not paid for it.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

                    Comment


                    • #40
                      opportunity loads for excess energy, KWH

                      SUOTE=inetdog;106881]But if the uncompensated power back to POCO does not cost you anything to generate, it is not a LOSS. It is an unrealized income.
                      It is a good reason not to oversize your system, but unless you have opportunity loads that you can turn on for local use, such as water heating, to keep your production at maximum, there is no point in throttling back your output to avoid giving away power.
                      And any expense for systems to avoid that sad state of affairs would truly be wasted, since they would not save you anything.
                      Throttling systems make sense where you are not allowed to feed energy back into the grid, less to when you just are not paid for it.[/QUOTE]
                      Thanks for this thread!
                      Please bare with me. I have a GTI diy system. In my state you will not receive compensation for excess generation unless you sign utility contract, which is much below market value,what I pay. My system is a 1.1KWH PDT with a 3.0KWH inverter. No battery. So my economic ensentive is trying to take advantage of opportunity loads ,but how to do this? The utility meter dose give a LCD display indicating grid return KWH'S. The utility acknowledges they are not crediting or paying for my KWH'S. so I am stuck trying to take advantage of opportunity loads. Any suggestions?
                      THANKS LOST DIY GUY

                      Comment


                      • #41
                        The utility acknowledges they are not crediting or paying for my KWH'S. so I am stuck trying to take advantage of opportunity loads. Any suggestions?
                        THANKS LOST DIY GUY
                        Install a Nyle system on your water heater (only if non-electric). Then, using a timer, operate only during daytime. Will soak up some of that overage.

                        Another option is to get a Volt or similar EV that has the capability to charge only during daytime hours. Volt has the capability, don't know about other makes.
                        Last edited by inetdog; 10-27-2014, 04:02 PM. Reason: fixed quote tag

                        Comment


                        • #42
                          Victron now has a solution.

                          Here is an update on the topic.
                          Victron are making it possible to use all PV energy produced:

                          http://www.victronenergy.com/blog/20...b-1-available/

                          At first it looks easy and very neat.

                          Then you need to upgrade firmware.
                          Which you have to mail victron to get. Then you get into hardware trouble.
                          For the Multi inverter you need one kind of interface and for the mppt you nead an other to even upgrade.
                          Then you realize you need a whole new inverter with the latest processor to make this happen and if that wasn't enough, you also need a new monitor device, a color control gx apart from cables and stuff.

                          I must be mad but I'm pursuing this and will tell you how it goes.

                          Sun just gone down here in Stockholm.
                          Cheers
                          /Olberg

                          Comment


                          • #43
                            Originally posted by Olberg View Post
                            Here is an update on the topic.
                            Victron are making it possible to use all PV energy produced:

                            http://www.victronenergy.com/blog/20...b-1-available/

                            At first it looks easy and very neat.

                            Then you need to upgrade firmware.
                            Which you have to mail victron to get. Then you get into hardware trouble.
                            For the Multi inverter you need one kind of interface and for the mppt you nead an other to even upgrade.
                            Then you realize you need a whole new inverter with the latest processor to make this happen and if that wasn't enough, you also need a new monitor device, a color control gx apart from cables and stuff.

                            I must be mad but I'm pursuing this and will tell you how it goes.

                            Sun just gone down here in Stockholm.
                            Cheers
                            /Olberg
                            Hi Olberg,

                            I am very interested in this. We have a Multiplus C 2000W 24V 50A which we bought in October 2013, would our inverter support the self consumption Hub-1 setup?
                            I have not bought our solar charge controller yet and am still deciding what to get.

                            This is for a very small cottage we have in a remote area in South Africa and are off grid. Currently we just charge our small 240AH FLA 24V battery bank with a 6kw manual start generator.
                            We were getting 48-72 hours of use from our batteries until we installed a pressure pump, we now get around 24 hours.
                            We have already bought 4 x Jinko 260W panels, and want to install these panels using a Blue solar charge controller more then likely the 150/70A.

                            My biggest issue is I do not understand how the Blue Solar MPPT charger will supply power to the Inverter as well as charge the batteries at the correct voltage?
                            Then the second issue is that we have 2 12V 100AH boat batteries for running our sneaker motors on our Small trout boats which I would like to some how charge using the solar.
                            99% of the time the cottage is only used on the weekends so ideally I want the solar to create a situation where we do not need to run the generator on the second day if there is sun, which in South Africa there mostly is, and that we can connect up one of the 12V batteries to slowly charge when there is excess solar energy, we have someone up there who can then switch the charger over to the second battery after a few days to charge the second boat battery if we leave them to charge, so they do not need to charge at the same time.

                            Any news on the new victron self consumption system, do you think my Multiplus compact will support HUb-1 with a new Blue solar MPPT?
                            Unfortunately I am no up there for a while and do not know the firmware installed.
                            How would you propose I charge the 2 x 12V batteries, should we use a 220 charger connected to the inverter or should I connect up a 24V - 12V charger which I some how turn on when there is excess solar energy? (I was hoping I could use Blue Solar's the relay to control this, but not sure how it would know how much power to supply to keep the 24V batteries at float and run the 24V charger?

                            Let me know what you think?

                            Comment


                            • #44
                              Hi
                              I'll try to answer your questions but do also check out Victrons homepage where you will find more extensive info.

                              The 150/70 charger will know what to do (after you set it up) and keep the batteries charged.
                              The batteries neg and pos are connected to both the charger and the inverter.
                              As in the last pic here:
                              http://www.solar23.com/victron_multiplus.html

                              In my world it seems extremely unnecessary to run a gas generator when you have so much sun!

                              The excess energy from hub1 is AC out (110 or 220V depending) and could be used with an external charger as you propose.
                              Read more about hub1 here:
                              http://www.victronenergy.com/blog/20...b-1-available/

                              Hub-1 is only possible with certain processors. You recently bought your multi, so I would expect you have a new one
                              (Check your number and compare here: http://www.victronenergy.com/upload/...plained-EN.pdf )
                              I have an old processor and need to buy a new multi to get hub1. I have more important stuff to buy, so my hub1 system will have to wait.
                              But I did buy their color control gx and I can check on all the solar system data possible on both phone and computer.

                              I'm a bit angry with my old multi at the moment because autumn is here, no sun for 5days and my batteries are down at 70% SOC and the multi seems very picky and rejects my generators sine wave. (at least i think this is the problem).
                              Perhaps you have some tips on generators and multis?

                              Best
                              /Oliver

                              Comment


                              • #45
                                Hi Oliver,

                                I had the same issues with the Inverter not accepting the generators power. I put in a second hand, Low end generator. It took a some fiddling but eventually with the right settings on the Victron Multi it started to charge off our generator.
                                Something rings a bell that it would not work in UPS mode and I think we had to fiddle with the frequency and there was some strict option which needed to be unticked. But I haven't fiddled in a year and have been installing schneider equipmet since then so might be getting mixed up.
                                I can't remeber exactly what we did to get it right, if I pop up this week to our cottage I will download my config for you.

                                I am not sure of the firmware we are running but:
                                The s/n of the unit is (SN:13049201550)
                                Its description is: MultiPlus C 24/2000/50-30 (CMP242020000)

                                Is there anyway that I can find out if the new firmware (xx3xx) supports this or do I need to know the firmware in order to know this?

                                Comment

                                Working...
                                X