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  • #16
    Originally posted by silversaver View Post
    I recently received my SCE POCO bill and learn even I am in standard Domestic plan (4 tiers pricing), SCE still pay me all tiers price... I thought net metering is 1 for 1 trade and they will only pay me tier 1 rate for excess production. I guess if I keep myself in tier 1 and I'll be fine after getting the EV. All about planning...
    You are fortunate, but not unusual in that in most states which have net metering laws the utility is required to factor in both Time Of Day and Tier when crediting you for the power exported back to them.
    Otherwise you would be selling low and buying back high during the dark hours or selling at Tier 1 and buying at Tier 4.
    As for your total excess production at the end of each one year cycle, you will be lucky to get anything at all.
    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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    • #17
      Originally posted by inetdog View Post
      Not a big enough difference among those choices to worry about, IMHO.
      Go for match of current, don't worry about match of voltage, FWIW.
      If the 255W panel costs more, you may not get back the extra cost as extra power. If they cost the same, go ahead and use one 255.
      Thanks for the advise. The panels were same price and I order two of 245W panels to be install next month. I just happen to have 1 of 255W spare panel sitting in the garage and wondering if I should use it first since all these panels will be degrading overtime and it might be an good idea to use the 255W panel now.

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      • #18
        Add 2 X 245W panels to the arrays, but only getting about 50% of total output. A 7kW DC gets instant output of 3kW, any idea? Look like I'm only getting power from 1 string instead of both strings. Nothing is been done at ground level, just adding 1 panel to each string.

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        • #19
          Originally posted by silversaver View Post
          Add 2 X 245W panels to the arrays, but only getting about 50% of total output. A 7kW DC gets instant output of 3kW, any idea? Look like I'm only getting power from 1 string instead of both strings. Nothing is been done at ground level, just adding 1 panel to each string.
          Two highest probabilities:

          1. One of the new panels is bad.
          2. You messed up the wiring on one string. It could be as simple as reversing the polarity on one added panel, since that would lower the string Voc below the Vmp of the other string.

          Either way, it is troubleshooting time up on the roof. <sigh>
          SunnyBoy 3000 US, 18 BP Solar 175B panels.

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          • #20
            Originally posted by inetdog View Post
            Two highest probabilities:

            1. One of the new panels is bad.
            2. You messed up the wiring on one string. It could be as simple as reversing the polarity on one added panel, since that would lower the string Voc below the Vmp of the other string.

            Either way, it is troubleshooting time up on the roof. <sigh>
            Thanks for the input. I can't believe the installer says the output looks normal lol and they wanna charge me 6 hours labor X 2 guys total 12 hours for adding 2 panels..... enough say...

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            • #21
              Originally posted by silversaver View Post
              Add 2 X 245W panels to the arrays, but only getting about 50% of total output. A 7kW DC gets instant output of 3kW, any idea? Look like I'm only getting power from 1 string instead of both strings. Nothing is been done at ground level, just adding 1 panel to each string.
              Get a clamp on DC ammeter on each string; that should immediately show if one is
              grossly under producing. It gets a lot harder after that, but I'd start by looking over
              the work done on the bad string. One approach is insert an MC4 "T" in the middle of
              each string, the 3rd branch capped with a dummy except when using it for measurements.
              The center point will be about equal potential from either end of a properly working string.
              A bad string will likely have something entirely different. Don't break paths with
              current flowing. Bruce Roe

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              • #22
                I'm only getting half of the output from my solar today. All the sudden in the afternoon the arrays stop outputing and inverter shows the message:
                Attached Files

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                • #23
                  Originally posted by silversaver View Post
                  I'm only getting half of the output from my solar today. All the sudden in the afternoon the arrays stop outputing and inverter shows the message:
                  I'd call the vendor.

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                  • #24
                    Originally posted by silversaver View Post
                    I'm only getting half of the output from my solar today. All the sudden in the afternoon the arrays stop outputing and inverter shows the message:
                    If the inverter is one which incorporates a DC Arc Fault Circuit Interruptor (AFCI), then the most likely cause is either a bad connection (extra resistance or even spark gap in series with the panel output), called a series arc fault; or a sparking/arcing short circuit on the DC side, called a parallel arc fault.
                    Either way, most likely in the wiring or connectors of the new panels. Remember that plugging in or unplugging an MC4 with current flowing will damage it.

                    If it is not one of those, it might be the result of really strong electrical interference, as from a radio transmitter.
                    SunnyBoy 3000 US, 18 BP Solar 175B panels.

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                    • #25
                      I'm not sure what might be the cause, but I'm sure my installer will let me know on Monday. If I'm gonna pay $1,500 labor to install 2 panels, they gotta be really good...... Turst - sometimes can be ..... darn

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                      • #26
                        Originally posted by inetdog View Post
                        If the inverter is one which incorporates a DC Arc Fault Circuit Interruptor (AFCI), then the most likely cause is either a bad connection (extra resistance or even spark gap in series with the panel output), called a series arc fault; or a sparking/arcing short circuit on the DC side, called a parallel arc fault.
                        Either way, most likely in the wiring or connectors of the new panels. Remember that plugging in or unplugging an MC4 with current flowing will damage it.

                        If it is not one of those, it might be the result of really strong electrical interference, as from a radio transmitter.
                        Installer came in this morning saying they unplug and re-plug the wires with current flowing, and maybe that is why AFCI happen. So he reset the inverter and it seems to work again. I left for 10 min and came back to check inverter's output, with in about 15 min I saw "DI MEAS" message with amber light twice for a short while and system back to green again. Is that a normal operation or something I need to be attention?

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                        • #27
                          I guess system is back to live. Without talking about the money spent, completely worth of the effort.

                          The SMA 6000TL-US-12 inverter with class-leading CEC efficiency of 98.5% is very nice, but it offers very narrow MPP voltage 345V/480V. My orginal setup with 2 strings of 13 Bosch 255W panels, the normal operating voltage is only 348V which only 3V higher during normal Summer temperature of 33C. When temperature reach over 35C, the inverter starts to loss power since the operating voltage drop below 344V. I found this issue during hot days in late April. Contact the installer with an answer - they setup the solar system base on average hot days..... I cannot imaging what will happen during hot Summer days or when solar arrays start their degrading dropping the voltage output. I knew I need to do something not counting on vendor. After playing with SMA Sunny Design Tool, I think by adding 1 panel to each string will solve all my problems. So I start my panel addition project includes tree removal to avoid tree shading in the late afternoon. Prior tree removal, my solar has not reach of 43kWh since Dec 2013. After tree removal, It has break the 43kWh mark. I know that is not a good result for a 6.63kW solar. I guess the panel addition not just increase operating voltage, it also increase the min voltage of solar array so the inverter wake up ealier and rest little later than before. I guess 47+kWh is not bad after all.
                          Attached Files

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                          • #28
                            Originally posted by silversaver
                            My orginal setup with 2 strings of 13 Bosch 255W panels, the normal operating voltage is only 348V which only 3V higher during normal Summer temperature of 33C. When temperature reach over 35C, the inverter starts to loss power since the operating voltage drop below 344V.

                            So I start my panel addition project includes tree removal to avoid tree shading in the late afternoon. Prior tree removal, my solar has not reach of 43kWh since Dec 2013. After tree removal, It has break the 43kWh mark. I know that is not a good result for a 6.63kW solar. I guess the panel addition not just increase operating voltage, it also increase the min voltage of solar array so the inverter wake up ealier and rest little later than before. I guess 47+kWh is not bad after all.
                            Yes that is cutting the low end voltage too close. I don't think the added voltage will
                            have a significant effect on wake up time. But it certainly will increase energy, as will
                            shadow reduction. Bruce Roe

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                            • #29
                              I'm still getting "dI Meas" error message from SMA inverter once in the while. Look at manual it says inverter detect deviation of current and power off then power on again. Is this something normal?

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                              • #30
                                Originally posted by silversaver View Post
                                I'm still getting "dI Meas" error message from SMA inverter once in the while. Look at manual it says inverter detect deviation of current and power off then power on again. Is this something normal?
                                Does the manual explain what the inverter is measuring to determine the "deviation or cycling of power" error?

                                It could be the lack of the panels producing enough power going to the inverter (cloud cover or shade) or maybe there is something going on with the POCO grid that is activating the "anti is-landing" safety in the inverter.

                                I worked on a project for a 1MW system at a high school that their inverters kept going off line for 5 minutes. We found that due to load fluctuations on the POCO distribution system was causing a "frequency shift" to change beyond a safety limit set in the inverter. We had the inverter techs increase the safety limit set point from the bare minimum up higher but still within a safe parameter and the problem went away.

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