WHAT TO CONSIDER
Before you get solar panels installed here in Perth there are quite a few considerations about system design that you need to know. It’s not just the case of picking an inverter and panels and installing them wherever they fit on your roof but there is a lot of mathematics involved in the design of your solar system. That’s why it is important to make sure that when you receive your quotes that you know whether a Clean Energy Council Accredited Solar Designer has designed your system. In residential premises we aren’t allowed to go above 600V DC for each string which generally means 12 panels connected in series. There are inverters that can handle higher amounts of current into the MPPT input compared to others which allows panels to installed on three aspects of your roof. by joining an equal number of panels in parallel. Fronius is one of the only inverters that allows us to parallel strings into the MPPT inputs.
A pattern that we stand by and regularly see here in Perth is a combination of North and West facing panels. We choose North because of the better output through winter and West facing panels to offset the afternoon air-conditioning and pool pump usage. Ideally each system is designed so your solar panels will offset the power when you use it, which could be different for a lot of people. Here’s a fact that you wouldn’t believe, South facing panels give the highest yield in summer over north facing panels. Realistically not everyone has the space or the aspect roof that is desired yet it is still beneficial to install solar panels anyway. Today we are installing 370W panels in a in a combination of 7-11,8-10 and 9-9 depending on which face requires more panel offset.
HOW DO FEED IN TARIFF’s AFFECT DESIGN
When the 47c feed in tariff was in play, the best way to save money with solar was not to use it as it was produced but to feed it back into the grid and buy your power back off synergy for half the price. Once the 40c ran out consumers were left with 7c. This changed things drastically. The idea now was that it was more beneficial to use the power as it is produced to save buying it from synergy and any excess you had you would get your credit for. But as of September 2020 the latest feed in tariff came into play, the Distributed Energy Buyback Scheme. This scheme has split the feed in tariff into two parts. If you generate excess solar power before 3pm then you get 3c per kW credit and after 3pm you get 10c per kW. WIth this in mind it is more beneficial to export after 3 pm with panels on the west face but ideally your still better off still using the power as it is being produced. Why the change in the DEBS? Personally this change came about due to high grid voltage during the middle of the day as the take up on solar power has radically increased. When most of us are at work during the day and not at home to use our power it all flows back into the grid and cause the voltage to escalate. This can cause inverters to trip out if the voltage goes up and over 258V AC. The answer is that Synergy and Western Power are encouraging consumers to install batteries which would help smooth the grid voltage out during the middle of the day. Sadly the price of battery storage is priced out of proportion compared to the saving a solar system provides.
