Going Green – Inverter Installation Part 2

SchicksBack-up Power, Solar Power1 Comment

Having finally received the new Hybrid inverter the time had come to get the necessary wiring done. This was never going to be a simple installation as most of the power supplies to the existing house circuitry had to be moved from one side of the house to the other.

The first step was to identify which circuits were required and then to install the new wiring from the ceiling void to the location of the new distribution board.

Inverter WiringThis ended up being a bit tricky for a slightly overweight, 6’4″, middle-aged man crawling around in a rather tight ceiling void.

Fortunately a timely visit from one of my vertically challenged friends helped to get things done. With the promise of a few cold beers afterwards, he got sent to the ceiling void to get some cabling pulled through to the garage.

This got done without any more damage to the ceilings – I had managed to stick my foot through the ceiling already!

The way the house was originally wired meant I had to install 2 x 2.5sq.mm twin and earth cables for the lighting circuits, 2 x 4.0sq.mm twin and earth cables for the plug circuits, 1 x 4.0sq.mm cable for the geyser circuit and a 16sq.mm twin and earth cable for the new main supply to the garage distribution board. The original stove circuit would remain connected to the existing distribution board as re-wiring it would be impractical, not to mention unnecessary. All the supply is needed for is the oven light and the ignition system. Without power, the gas stove can still be lit with a match. The supply to the pool pump also stays on the existing supply as this would not be fed from the inverter system.

All the wiring was left coiled in the ceiling for when the final connection happened. There was still quite a bit of work to do before the new wiring could be connected to the existing circuits.

Distribution Board Installation

DB-1The next step was to clear a space on the wall in the garage and install the new distribution board. The panel is built up out of smaller panels each with a specific purpose in mind.

There are four 12-way panels and two 6-way panels that make up the complete distribution board. Each panel is mounted on a piece of MDF with sections of PVC trunking between the panels for the interlinking wiring.

Some 100 x 40 PVC trunking was installed from where the cables enter the garage to the new DB to contain the new wiring.

The panel is laid out as follows:

  1. Top right section houses the main incoming supply from the existing DB with feeds to the inverter main isolator and the geyser which remains on the normal non-essential supply.
  2. Bottom right section is fed from the inverter and feeds the lighting and socket outlet circuits.
  3. The top centre section houses two kWh meters to measure total consumption and consumption on the inverter side.
  4. The smaller panel on the top left contains the main inverter isolator.
  5. The bottom centre section is empty now and will be used as the solar string combiner at a later stage.
  6. The bottom left panel was earmarked for the main battery disconnect. It’s empty for now until I can fin a reasonably priced DC circuit breaker for this.

The next step was to install the equipment in the various panels.

DB-2

With the equipment installed I could start with connecting the main feeds and the circuit wiring.

DB-3Main feeds connected, the lighting and plug circuits still need to get connected, but not before the inverter is hung on the wall and connected.

DB-5With the inverter in, the circuit wiring could be completed.

DB-4With all the panel wiring complete, the next step was to install and connect the battery bank.

Battery Installation

Battery RackI knocked together a battery stand with some 25mm aluminium square tubing and Connect-It fittings. It’s sized to carry 12 batteries, but for now will only have 4 installed.

The rack is pretty sturdy and should have a problem carrying the eventual 200kg’s of batteries.

The rack will get placed directly below the inverter to keep the cable lengths to a minimum. This helps with volt drop between the batteries and inverter and also saves a couple of rand on the cable costs.

Battery Cables

The interlinking battery cables are made from 25sq.mm welding cable with crimped lugs and colour coded heat-shrink for identification.

 

 

 

Battery ConnectionCabling made up, the batteries could be installed in the rack and connected to the inverter. I have installed a 60A blade type fuse on the positive feed for protection.

This will get replaced with a 100A fuse or DC circuit breaker when the next string of batteries gets installed.

I wasn’t happy with the exposed battery terminals and needed to find something to cover them up. I thought it would be easy enough to walk into my local Midas and buy some battery terminal covers like you get car batteries, but no, all I got was a blank stare. Visits to other spares shops also proved to be fruitless, so I was left with coming up with another solution.

Battey Terminal 1A trip to the local Builder’s Warehouse eventually provide the solution: rubber caps that get used on chair legs or walking sticks! With a piece cut out for the cable entry, these fit perfectly over the terminals. With a blob of silicon paste applied to the terminals (Vaseline or grease would perish the rubber) these make neat little terminal covers.

Battey Terminal 2 Battey Terminal 3

 

 

 

 

This brought to an end the first part of the preparation work. The next step would be to strip out the existing distribution board and circuit feeds, connect the inverter supply and trace and reconnect the existing circuit wiring to the new feeds from the inverter distribution board. See part 3 of this article for the final installation.