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Is reliability keeping me on the grid?

Paul Ebert

Dr Paul Ebert | Specialist Advisor, Energy Transition, Newcastle | 09 August 2017

On the 23rd December 2016 at 6:30pm my 3kW rooftop solar system for the first time in six years stopped working. The resulting fallout has reminded me of the value of the grid, but also the opportunity that such systems bring.

This is a bit of story, but stay with me.

This system was installed in 2010 when, buoyed by State solar feed-in tariffs, a friend and I aggregated 52 systems across family and friends and attracted a solar installer from 1500km away who offered the best price and equipment. My system has worked flawlessly since, generating on average 11.6kWh per day exported through a gross metering arrangement where, for every kWh, I received the feed-in tariff. I washed the panels once in 2011, but otherwise left it alone and given the feed-in tariff it met a simple payback by mid-2012.

At the time of installation rooftop PV was still in its infancy and we spent significant time considering technology. We chose 16% efficient monocrystalline silicon panels from a Tier Two supplier from Korea, and the inverter eventually came from a Chinese supplier which we didn’t know, but who had local presence and half the cost of the known German equivalent while meeting standards and accreditation. It is worth noting that the installer has now gone out of business, the panel manufacturer is no longer manufacturing, and the inverter manufacturer has pulled out of the country.

When my system failed it was certainly strange timing. On the 31 December 2016, a week after this failure, the solar feed-in tariff ended. For about 150,000 systems within the State this reduced the value of the exported energy by around 90%, leading to a flurry of activity, uncertainty and confusion as the owners of these try and work out what to do with the power station on their roof. It has also made people face the reality of such generation, which an artificial feed-in tariff somewhat blurs.

When my system failed it was certainly strange timing. On the 31 December 2016, a week after this failure, the solar feed-in tariff ended. For about 150,000 systems within the State this reduced the value of the exported energy by around 90%, leading to a flurry of activity, uncertainty and confusion as the owners of these try and work out what to do with the power station on their roof.

Lesson number one - these are not toys

It is worth noting what failed on my system. It was the inverter, which I had housed in my garage as I was suspicious of its ability to withstand the rigours of outdoor installation. This was a good choice, as many of the other inverters we installed suffered terribly in outdoor locations, with significant corrosion and failure of things like the LCD screen – more inconvenient than fatal.

But with my inverter, it was a serious failure including physical damage – in the photo below there should be three yellow transformers along the top, the left one has been blown off its mount. This failure, which appears to have been influenced by an electrical storm (perhaps lightning), showed as a “grid fault”. The AC fuse had also blown, and there had been a lot of heat, with the wall behind the unit showing signs of this.


Lesson number two - getting the system back online

Fair to say it took time, with the system successfully restarted at 11:30am on Monday 6 February 2017 – a month and a half after it first stopped!

This journey to recovery involved an insurance company, a number of suppliers, and a range of thinking around appropriate inverters to match not only the PV DC arrangement but also electrical protection; noting that the practices for all of said items have changed. The installer audited our existing panels and arrangements and could not find any issues, but stated that electrically they “would not be installed this way nowadays”. The industry has obviously evolved.

The replacement Austrian manufactured inverter is like science fiction to that installed in 2010. In only six years, the inverters have become more efficient, have better power point tracking including across two independent arrays at once, have in-built circuit monitoring and relays (so you can switch loads on/off depending on solar output), can supply grid reactive voltage control and have a wireless internet connection for vendor and owner operational scrutiny – in fact, the vendor helped set the unit up remotely and now monitor output in their control centre.

Solar panels on roof

But this journey really made me think. What would I have done if I was not grid connected? It took serious time to rectify this situation, and there was no-one to point the finger at or get help from my original suppliers.

Just recently I have had conversations with several people who cannot wait to get “off the grid”, citing the independence from “utilities” and control of their energy destiny as the major drivers. I can understand this rhetoric, and for me there is a great deal of satisfaction about generating your own energy off your own roof. I recently installed a solar hot water system and have not used one unit of input energy for hot water since – it makes sense in the location I live.

But I have to question the electrical off-the-grid value proposition. In my circumstance, I would not have had a power supply for some time, and while I think there are ways around this, in 30 years of paying electricity bills the longest I have been off the grid was just 6 hours following a major storm event. Sure, people’s circumstances and situations are different and there are obvious places where grid disconnection makes sense, like those on the fringes of grids with expensive grid connections, and in my situation I benefit from 50 years of public grid investment; but that reliability is a major responsibility which I am not sure people truly understand or correctly value.

This new inverter has several other capabilities which do incline me to more autonomy – actually, not autonomy, but being much smarter with the way I use my PV generated electricity. The inverter can handshake with other home energy management devices, including batteries, transducers, switches and tariff controllers. This can help me optimise my energy flows, arbitraging load to when it is cheapest and limiting my peak draw and hence reliance and impact on the grid. But that grid connection stays, and I really appreciate the reliability value it brings.

I have no doubt that rooftop PV will be the lowest cost supply option at the point of load in many places , but it will also have to integrate and operate within a bigger market construct. There are some hard truths lurking in here. Every system that has attracted a feed-in tariff like mine has been riding on the back of the grid and other energy users, and such tariffs are ultimately unsustainable – sure, they have done what they were meant to, driven evolution in rooftop solar and significant cultural change in a whole lot of good ways, but long term it should only do so in a manner that is fair, equitable, and allows optimisation across the whole consumer spectrum, which is of course no easy thing.

To get to the point where value crosses to everybody is going to take even more change. This will involve evolution and innovation in the way such systems use and interact with the grid – smart network owners already know this and are working towards optimising that future, something I’m touching in my professional role. It will also raise the prospects of innovative retail options, something my new inverter has already allowed me to consider and I’m now in discussion with several new entrants into my local supply equation who offer really attractive concepts - this would have all been unrealisable gibberish only a few years ago.

It makes you wonder just how far this might go. I think it is a very exciting future, and while I don’t trivialise the broader issues at play, and how much we still have to learn, ultimately this could be a very big, intriguing opportunity for us all.

This article was originally published on LinkedIn.

Paul Ebert

Dr Paul Ebert

Specialist Advisor, Energy Transition

Paul is an expert in global energy transition issues and a senior member of Worley’s energy transition team. With a doctorate in wind energy, he has had a twenty year career in the evolving low emissions sector covering a very broad range of technologies, hybrids and enablers, and both market and policy constructs across a broad range of industry sectors. These roles have included project management, development, specialist technical and advisory input. Paul is a member of several governance boards.