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Solar Conversions EQ and MidNite Solar breakers

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  • Solar Conversions EQ and MidNite Solar breakers

    I'm just finishing up our new solar panel AGM battery system for our remote cabin in Ontario, where we recently found out that the trusty propane-mantle lamps trip the new CO alarm! It turns out we've been breathing too much CO for years by using those lamps! So we switched to solar PV panels to power 10 warm-light 2W LED lamps. Since our battery bank is 24V, I bought a SolarConversions(SC) EQ-12/24-20 which promises to also help balance voltage between the 2 12V AGM 110aH batteries. My question is how to wire in a pair of MidNite Solar circuit breakers.

    Following the wiring schematic provided by Solar Converters (SC), I plan to attach the SC common flying lead to the 24V battery bank (-) common using a bus bar. However I plan to install a circuit breaker to the 24V (+) flying lead and the 12V flying lead (which attaches to the jumper between the 12V batteries). When connecting to the 24V (+), I'd like to add a second 10 ga. wire to the (+) side of the breaker that feeds the MPPT controller. It seems like the breaker (+) terminal opens wide enough for a pair of 10 ga wires, but is it bad form to try to connect both at that terminal? Otherwise I can move the wire to a nearby terminal strip where I can distribute 24V (+) power to both breakers. I have the idea that I should try to minimize wiring connections especially for lower power systems, like our 24V cabin.

    I don't have a 2-pole circuit breaker for protecting/switching the two power leads of the SC EQ, so I'm going to use two separate breakers. I'll order a 2-pole breaker and replace the separate breakers later in the winter.

    Finally, what do you think about the Solar Conversions EQ device? My main use is to provide a 12V output for charging the cellphone and E-reader, however I like the idea that it will help keep my two AGM batteries in balance both during charging and discharging.

    We have a small generator in case we don't have enough winter sun to keep up with our anticipated demand of around 400W/day.

    2x250W panels, MidNite Solar Kid 30A, 2x12V 110 AGM

  • #2
    Originally posted by North_of_Superior View Post
    I don't have a 2-pole circuit breaker for protecting/switching the two power leads of the SC EQ, so I'm going to use two separate breakers. I'll order a 2-pole breaker and replace the separate breakers later in the winter.
    Hope you don't have to pass inspections or have the place insured. Huge code violation and really stupid. If you do that and a fire results. You will be held liable for all property damage, injury, and death.
    MSEE, PE

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    • #3
      Originally posted by Sunking View Post
      Hope you don't have to pass inspections or have the place insured. Huge code violation and really stupid. If you do that and a fire results. You will be held liable for all property damage, injury, and death.
      The Solar Conversions schematic doesn't show breakers at all, instead just connects to the battery bank directly. They claim each power leg of the EQ device in internally fused. I thought the breakers would let me switch off power in case I wanted to remove the device. I'm not clear which is the really stupid part: using breakers at all, using single-pole instead of 2-pole breakers or using the EQ device.

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      • #4
        Originally posted by North_of_Superior View Post
        The Solar Conversions schematic doesn't show breakers at all, instead just connects to the battery bank directly. They claim each power leg of the EQ device in internally fused. I thought the breakers would let me switch off power in case I wanted to remove the device. I'm not clear which is the really stupid part: using breakers at all, using single-pole instead of 2-pole breakers or using the EQ device.
        Is your system grounded or floating? I do not mean the chassis as it is required to be grounded. I mean the system. Are any circuit conductors bonded to earth or something in place of earth like the chassis of a car.
        MSEE, PE

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        • #5
          Originally posted by Sunking View Post
          Is your system grounded or floating? I do not mean the chassis as it is required to be grounded. I mean the system. Are any circuit conductors bonded to earth or something in place of earth like the chassis of a car.
          Floating system. Only the panel and controller chassis are grounded.

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          • #6
            Originally posted by North_of_Superior View Post
            Floating system. Only the panel and controller chassis are grounded.
            Exactly what I thought and why I asked. It was a trick question you could not answer correctly. That being said the dual breakers have to be Ganged together because both circuit conductors are HOT and must be switched off together as a unit whether manually if you operate or automatically in the event of a fault. That can only be guaranteed if they are Ganged together as a unit. If the system was grounded, you would not be allowed to use them because in any grounded system the grounded circuit conductors are not allowed to be switched and must be electrically bonded at all times in order to protect the circuit conductors at all times.

            There is no safe or compliant way to use them unless Ganged correctly.
            MSEE, PE

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            • #7
              Originally posted by Sunking View Post
              Exactly what I thought and why I asked. It was a trick question you could not answer correctly. That being said the dual breakers have to be Ganged together because both circuit conductors are HOT and must be switched off together as a unit whether manually if you operate or automatically in the event of a fault. That can only be guaranteed if they are Ganged together as a unit. If the system was grounded, you would not be allowed to use them because in any grounded system the grounded circuit conductors are not allowed to be switched and must be electrically bonded at all times in order to protect the circuit conductors at all times.

              There is no safe or compliant way to use them unless Ganged correctly.
              OK, thanks for the design help. I want to avoid all injury, fire and death in all my projects! Since Solar Converters doesn't show any additional over-current protection between their device and the battery bank, I won't add anything until I can get a 2-pole breaker. I think I have a 60A DC-rated 2-pole disconnect that I can install so I can switch the EQ off.

              Any thoughts on the EQ device itself? Any merit to the idea of balancing voltage between batteries?

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              • #8
                Let me go look later. Don't have time right now. Got a link to the device in question to save me some time?
                MSEE, PE

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                • #9
                  Originally posted by Sunking View Post
                  Let me go look later. Don't have time right now. Got a link to the device in question to save me some time?
                  The EQ 12/24-20 from the company:
                  http://www.solarconverters.com/index...q-proper-usage

                  As advertised by the vendor (altestore.com): http://www.altestore.com/store/Charg...nverter/p1284/

                  Looks like it'll let me draw 12V in a balanced way with advertised 96% efficiency. I called Solar Conversions and they said the device uses 50mA, but I'm not sure if he meant at 24V or 12V. This device seems unusually efficient compared with other DC-DC converters, which advertise much lower efficiencies.

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