Please read My journey to Off Grid Solar systems part 1 & Part 2 if you haven't done it already. In this article we're going to check how all these pieces comes together. To show you that I would like to present below diagram. Please note that this is a basic diagram and with related to the laws of where you currently live in this could be bit different.
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Let's start with solar panels. My solar panels are connected parallel. Why? This is not to overload my solar charge controller's "Open circuit Voltage" limit. The open circuit Voltage limit will vary depending on your battery voltage. I'm using a 24V battery. So, for my Solar charge controller in 24V, the maximum open circuit Voltage is limited to 105V. Open circuit Voltage is marked in your solar panels. For mine it's 48.9V so, if I connect them in Series it will generate 146.7V (I have 3 solar panels) When in parallel all 3 solar panels will stay at 48.9V but the current is getting increased. To handle the increased current, my solar panels are connected to DC breakers by 8mm (8 AWG) DC solar cables.
The DC breakers are rated at 63A. Solar panel manufacturers recommend using a 20A fuse per panel. I have 3 panels so it adds up to 60A in parallel. From the DC breakers to the solar charge controller, I have again used 2 x 4mm DC solar cables.
The solar charge controller connects to the battery using another two 4mm DC solar cables. I didn't use a breaker here because if it shut off during day time for any reason my solar charge controller can be destroyed. The downside of this is to turn off the power to the solar charge controller, I have to disconnect the wires from the battery.
My inverter connects to the battery using a separate 4 x 25mm (4 AWG) battery cable with M8 connectors.
Inverter output goes through a Sonoff Pow R2. I used this to protect the inverter from overloading and also to monitor energy usage.
Output from Sonoff Pow R2 is connected to an automatic change-over switch which helps me to switch between Inverter and Grid Power.
Grid power comes to the change-over switch through another energy monitor device which works as a protection device and a main switch. I use this device to cut off Grid Power so my automatic transfer switch can connect the inverter to the house. This device also has high and low voltage protection and also controls how much current it should allow to pass through. I almost forgot, this device also tracks energy usage so I know how much power I use from the grid.
The automatic transfer switch output goes to my main power distribution board.
And that's how all these are connected.
The DC breakers are rated at 63A. Solar panel manufacturers recommend using a 20A fuse per panel. I have 3 panels so it adds up to 60A in parallel. From the DC breakers to the solar charge controller, I have again used 2 x 4mm DC solar cables.
The solar charge controller connects to the battery using another two 4mm DC solar cables. I didn't use a breaker here because if it shut off during day time for any reason my solar charge controller can be destroyed. The downside of this is to turn off the power to the solar charge controller, I have to disconnect the wires from the battery.
My inverter connects to the battery using a separate 4 x 25mm (4 AWG) battery cable with M8 connectors.
Inverter output goes through a Sonoff Pow R2. I used this to protect the inverter from overloading and also to monitor energy usage.
Output from Sonoff Pow R2 is connected to an automatic change-over switch which helps me to switch between Inverter and Grid Power.
Grid power comes to the change-over switch through another energy monitor device which works as a protection device and a main switch. I use this device to cut off Grid Power so my automatic transfer switch can connect the inverter to the house. This device also has high and low voltage protection and also controls how much current it should allow to pass through. I almost forgot, this device also tracks energy usage so I know how much power I use from the grid.
The automatic transfer switch output goes to my main power distribution board.
And that's how all these are connected.
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