How did we solve it? We laid another cable single phrase 35mm2 directly from the solar inverter to our meter box bypassing our undersized cable 3 phrase 10mm2 home connection. This way we eliminated the large voltage gain being caused by the inverter output. The 35mm2 cable only had a voltage gain of 7 to 8 volts.
Helpful advice for others who want to install solar systems !
1. Check where you are located. Urban areas generally have short connection lengths from street to house. Also they usually have a large number of customers over short local distribution lines. Semi-rural and rural areas can have long connection lengths from street to house. Also they can have small numbers of customers over long local distribution line. The Power Supplier will generally have higher starting voltages to compensate for the losses in the distribution and connections lines. Unfortunately this works against the solar system generator.
2. Check with your Power Supplier what the maximum voltage they are providing at your meter and what the grid impedance is at your meter. This can affect the size of the solar system you can install.
3. Check if you can the size of your connection cable from street to your house. Even with urban areas, if your house connection cable is undersized, it may not be able take your solar system to higher output system. With older houses your cable sizes may be as low as 6mm2. 16mm2 connection cable will be the minimum size required. In semi-rural and rural areas the distance from our house to the distribution line take off point is critical. With high starting voltages and long distances may require cable size upgrading to be able to stay below the upper voltage limit (264 volts is the Australia standard).
4. Select a Solar System installers who understands what the potential problems can be and who is willing to assist in dealing with the Power Supplier.
5. Don't proceed with the installation of larger systems (>1.5Kw) unless your system installer and power supplier can give you assurance the system will work to it's design capacity.
Solar Systems Observations.
1. Solar panels are designed to operate at their maximum at 25 degrees. Their performance becomes less and less the hotter it gets over 25 degrees. e.g. 25 degrees 5000 watts 30 degrees 4500 watts 35 degrees 4000 watts. Sunny Spring and Autumn days are the best production times.
2. Solar panels don't have to face true north. Ours are 36 degrees off north and still have a 96% efficiency rating.
3. All states except NSW and ACT use gross tariff method. The less power you use while the sun shines, the more power you can export to the grid.
4. When you export to "the grid" you are only exporting to your local distribution line. The Power Supplier's transformers are designed to download to it's distribution lines not upload it back further into the grid. That is if all your neighbour's installed large solar systems then you could have the situation where no one would be able to export to "the grid".
5. The South West of WA the average daily production for a 6 panel system is about 4 KWh(Units).
|Inverter Production Readout|
|Graph of Production, Consumption and Grid Export|
10 to 30 Solar Panels
The company we used was Solvation - A small company based in Fremantle, Western Australia. Alex Ackerman the owner/manager was very professional, very helpful and gave excellent service. He assisted us through the whole process of our initial 1.05Kw system to the upgraded 4.6Kw system.
So any one considering getting solar panels installed we would highly recommend Alex and his team .