Jan 4, 2015: Our Solar Power System

Everything is going very nicely at the Greeny Flat. Our passive solar shading is working well to help keep us cool on the hottest days. We’re lucky that we generally have cool nights in this part of the world. It allows us to open up the house at night and cool down the concrete slab which then works to keep us cool during the day.

We’ve had plenty of sunshine too so our solar power system is producing loads more electricity than we are using. A number of people have asked me for details about the system so I thought I’d better put it writing. To summarise, we have a 3kW grid-tied solar system with twelve 250W ‘Trina’ panels and an SMA ‘Sunny Boy’ inverter. The system was installed by ‘Evolved Electrical’ from Campbelltown and cost a total of $4,650.

The Greeny Flat’s 12 ‘Trina’ solar panels are mounted on the garage roof.

Our Solar Panels

Before settling on a system or an installer we had lengthy discussions with numerous companies and product reps about the best types of panels and inverters to use. Most of them agreed that ‘Trina’ panels were the best value for money. Others like ‘Sunpower’ have higher efficiencies and longer warranty periods as well as bigger price tags. ‘Trina’ seemed to be the best compromise between cost, quality, reliability and warranty. They come with a 10 year (workmanship) and 25 year (linear power output) warranty.

Trina panels are made in China. It would have been nice to use Australian made panels but we couldn’t find any through any of the local installers that we spoke too. We could have used panels made in either Europe or the US but they would have cost significantly more. Since our only option was to use panels that had been transported a long distance thereby supporting some other country’s economy we decided that it didn’t matter where they came from. So our choice was based on recommendations from ‘experts’ who all seemed to agree that ‘Trina’ were the best value.

Our SMA ‘Sunny Boy’ inverter mounted next to the electrical panel on the back of the garage

Our Inverter

We have an ‘SMA Sunny Boy – SB 3000TL-20’ inverter rated at 3kW. SMA inverters are made in Germany to a very high standard and come with a 5 year manufacturers warranty. Most of the installers we talked to recommended other brands like ‘Aurora’ as being the best value for money. In the end though we decided to spend a little more on the SMA because it is already set up to be connected to a battery storage system.

We don’t currently have battery storage because the price is still too high. But, hopefully in the not too distant future, we would love to be able to store some of our excess energy during the day for use at night. There is currently a massive amount of research and development going into energy storage systems and all indications are that within 3-5 years we should see some really good value options on the market.

Once that happens we will probably buy one. With the SMA inverter we will simply be able to plug it straight into the storage system and away we go. Most of the cheaper inverters do not have this capability built-in so we would have to switch inverters which would be an expensive proposition. So, for a couple of hundred extra dollars up-front we have a very high quality inverter that will likely save us a lot more than that when it comes time to buy an energy storage system.

Our Installer

Our system was installed by ‘Evolved Electrical‘ based in Campbelltown, NSW. The main deciding factor was price. Evolved’s price was significantly better than any of the other companies that we spoke to. We ended up paying a total of $4,650 and the next nearest quote was around the $7,000 mark. This did not include some extra work that we had to do to upgrade the existing electrical supply to the old house in order to be able to add the solar system.

If you are considering installing a system on an existing building, it is important to make sure that your existing wires and meters can handle the additional requirements placed on them by a grid-tied solar system. We ended up having to replace the electricity supply line from the pole across the street to the meter box because it was not a thick enough cable. We also had to add two new meters (one to measure the electricity we import from the grid and one to measure the electricity we export to the grid) and while we were at it we also chose to update the existing meters for the old house, the meter box (the old one had asbestos in it), and all of the wiring in the existing house.

Getting back to Evolved Electrical. They did a good job on the installation. They came when they said they would, got the job done in reasonable time, and did a good-quality, neat and tidy installation. In fact the only issue we have had with them was a paperwork one. They were supposed to have supplied us with an owner’s manual and certificates but so far, despite repeated prompting, they have not done so.

Regardless of the installer you use, I recommend that you do not pay the full amount of the bill until you are certain that every detail is finished and correct. In retrospect we should have withheld a small amount from our final payment until all of the necessary paperwork was completed.

Our Experience So Far

Apart from the minor issue mentioned above we have been extremely happy with our decision to go solar and with the system that we have installed. We spent about $300 extra to have the installers add a power metering device called a Wattson Meter which allows us to monitor both our usage and production of electricity in real time. If you are considering a solar system I highly recommend that you spend a bit more for something like the Wattson Meter.

Wattson meter display showing current PV production of 2.245kW

Not only does it help us monitor our day to day usage of electricity and see where we can use less. It also records our usage and production data so that we can review it on a regular basis. This allows us to learn about our overall patterns of energy use. It would also help to inform us if there was a problem with any of the electrical equipment in the house such as the solar power system, the electric booster on the solar hot water system, the water pump or the refrigerator.

The Wattson meter records information on how much  power is used and produced every day and when.

Apart from anything else, it’s fun to be able to see graphs like the one below that show just how much more electricity we are making (green) than we are using (red)… gotta love that!

Wattson Meter graph showing the total amounts of electricity used (red) and produced (green) in the Greeny Flat over the last eight months.