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Wetkit

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  1. Wetkit's post in ENERMAX ACD was marked as the answer   
    Ok, this looks like a newer type "Ripple Relay".
    Basically your local municipality can remotely disable the load connected to that device. They would only do that during peak demand times if the demand is too high.
     
    Green means everything is ok and working normally
  2. Wetkit's post in Battery Grounding? was marked as the answer   
    Right, so I spent some time on Google and read up a bit on the subject, as it seems to be a bit of an issue.
    Here is some links for your own benefit, granted they mostly from the US.
    http://www.homepower.com/articles/solar-electricity/design-installation/ask-experts-grounding-dc-systems
    http://www.solarpowerworldonline.com/2012/04/installation-practices-keep-your-pv-system-well-grounded/
    http://www.nmsu.edu/~tdi/pdf-resources/CC102.pdf
    http://www.nmsu.edu/~tdi/pdf-resources/CC103.pdf
     
    http://www.solarabcs.org/about/publications/reports/systemgrounding/pdfs/SystemGrounding_studyreport.pdf
     
    What it really comes down to, is that ALL exposed metal parts of any electrical system, be it AC or DC, needs to be grounded. That is the law.
     
    It is also stated, that if your PV voltage is higher than 50V, the positive, or negative, of the PV needs to be grounded. And this is where the probelms start.
    Go and have a good look at your MPPT, and you will find the negative input and output is common. So when you grounding the negative of the PV side, you in effect grounding the battery negative as well, through the MPPT controller.
    When we move over to the Invertor, you will find that the older type invertors that have an isolating output transformer, the DC negative is also grounded to the invertor chassis.
    The newer type transformerless invertors seems not to do this.
     
    So, at least ground all the metal parts. What is reccomended as well, is to have the PV ground wire seperate outside the building to an earth spike. Incase of a lightning strike, it will keep the flash outside your building while traveling down the earth wire, and not be a fire risk inside the building.
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