New MCB Set up:

If you recall the off grid system, I used an MCB enclosure (miniature circuit breaker), pictured below on the left, to manage the connects and disconnects for the 8 solar PV panels. This particular enclosure was configured so that each MCB would handle the 100w input from each panel.

But in our new setup, we actually only need 2 of the MCBs to control all the solar PV! That's because we have now wired 7 of the panels in series. Therefore, I can now use the first MCB to control the input for the 700W of solar PV going to the Mastervolt Soladin. The last MCB remains unchanged and comes from the last panel and onwards to the 300W grid-tie solar inverter.

Using MCB As A Turbine Brake:

OK, so now I started thinking - what if I can use the remaining MCBs as a turbine brake, given that each turbine has 3 AC outputs. That would allow me to fully utilise the remaining 6 MCBs, without having to buy dedicated turbine stop switches. The key here is how to configure the MCBs to act as a turbine brake. Here's how I configure them. Firstly, I take the middle 6 MCBs out of the enclosure, and reverse them around. Then I wire the bottom of each MCB with a cable looping to the next MCB so that 3 of the MCBs are joined together. You can see the yellow looped cables linking MCBs 2,3 and 4. I do the same for MCBs 5, 6 and 7.  This is what will create the turbine brake. Now, the first turbine's 3 wires are connected to the top of MCBs 2-4, and the 2nd turbine wires are connected to MCBs 5-7. An additional wire is also run from each of these top points onwards to the inverters handling each turbine. So, when current flows into the MCB, and it is turned "off", then the current cannot flow through the MCB, so flows onwards via the additional top wires towards the inverter. If we turn the switch "on", then current flows down through the MCB, hits the linked yellow wires, and thus creates the brake on the turbine. 

Inverter Switches:

Now that we have the brake configured, there is a further issue to contend with. Although the brake does stop the turbine, the current continues to flow onwards to the inverter. Ideally I would like to brake the current completely from the inverter, in case 3 joined together braked/shorted wires cause any problem or malfunction for the inverter. So to manage this, the 3 x 2 sets of wires from MCBs 2-7 are now routed to a separate 6 module MCB enclosure. This one has been configured in a standard way, with 2 cheap second-hand triple-pole MCBs fitted. Here we wire up in normal fashion, as shown below, with each triple pole handling each turbine current to each inverter.

With the controls in place, now its time to connect the grid-tie wind inverters to their respective dump loads, and organise the electricity sockets so that I have 4 sockets routed into the room in the right place. Each dump load will be located above the grid-tie inverters, to ensure that any heat generated can move upwards away from the inverters.

The 1st turbine controller is removed from the wall, and in its place we add 2 300W dump loads, linked in parallel, in order to handle the excess from the 1st turbine. As stated earlier, the 2nd controller also had a separate dump load, so now I remove the 2nd controller, leaving the dump load in place. We now connect the dump outputs from both inverters to each respective dump load, and tidy up all the cables. Here's the final schematic illustrating how the system has been configured - I have shuffled the MCBs around in the diagram, to aid readability, but all wiring corresponds to the actual system: 

Above you can see how simple the layout is for the solar PV - all we do is route the positive cables through the MCB switch and onwards to the solar inverters. The wind turbine wiring is more complicated, in order to allow for a brake function and an inverter disconnect switch. Lets move of to the final stage - testing the individual components and assessing day-to-day operation.....