Hello

I recently had an 8kw hybrid Sunsynk inverter installed. Solar is on the way so its currently running as a battery backup for pretty much the entire house. When solar comes, I would like to start using the inverter correctly and split the essential and non-essential loads. I'm also going to take the opportunity to replace a very old and poorly wired db board.

My plan is to split the board into three sections. Eskom only, essentials and non non-essentials. If I have excess generation from solar, feed back into the grid.

I'm confused with where to place, and how many Earth Leakage breakers I need.

Option 1: Single Earth Leakage

• Grid will feed a primary 63a dual pole breaker switching Live and Neutral. Live will go into a 30a breaker for the stove/oven
• 40a Earth Leakage feeding inverter
• 2x feeds return from inverter feeding essentials and non-essentials.
• Common busbar neutral for everything

Option 2: Two Earth leakages

• Grid will feed a primary 63a dual pole breaker switching Live and Neutral. Live will go into a 30a breaker for the stove/oven.
• Single pole 40a breaker feeding inverter
• Essentials from inverter into 40a Earth Leakage breaker
• Essentials Live and neutral busbar feeding house
• Non-essentials from inverter into 40a Earth Leakage breaker
• Non-essentials Live and neutral busbar feeding house 

Option two feels more correct, because i dont know what is happening internally with the inverter and if its going to cause all sorts of issue with the way it moves load around the circuits. 

I'm also a bit unsure of the neutrals. Can I have a common neutral or should they be split. Reading the manual for the inverter its not clear where to place the earth leakages, if at all.

Thanks
Mark

 

I think I may have misunderstood how the hybrid inverter with its management of critical and non-critical loads. Unless using the aux/gen, there is no second feed from the inverter. The post below helped me understand it a bit better.

So I think the correct wiring would be:

Option 3: Two Earth leakages, but correct?

• Grid will feed a primary 63a dual pole breaker switching Live and Neutral.
• Live will go into single pole 30a breaker for the stove/oven.
• Live will go into single pole 40a breaker feeding inverter (clean power, not EL protected)
• Live will go into first earth leakage feeding non critical loads 
• Return from inverter will go into second earth leakage feeding critical items

My understanding then is:

• Inverter will run 24/7 from battery supplying critical loads
  • PV charge batteries
  • PV provides power to inverter to charge and run critical loads
    • IF battery charge current + critical loads current is less than PV output, inverter will start back feeding into non critical loads 
    • IF battery charge current + critical loads current + non critical loads current is less than PV output, inverter will push back into grid (if enabled)

Does this mean that during load shedding, regardless of battery charge, there will be no power to non critical items? I would think so, because the grid side will effectively be short circuit during power outage?

 

10 hours ago, MarkRudling said:

Does this mean that during load shedding, regardless of battery charge, there will be no power to non critical items? I would think so, because the grid side will effectively be short circuit during power outage?

Yes there is no power to non critical items during load shedding.

This is how the inverter(ups) should be wired to be compliant with Sans 10142-1