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Norfolk Island has “too much” solar, now it wants storage

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One Step Off The Grid

Norfolk Island, the former penal colony and now tourist destination located nearly 1,500km off the east coast of Australia, is calling for proposals for energy storage to maximise its use of solar PV, minimise a growing “solar debt,” and cut its crippling electricity costs.

The island, with a population of around 1750, and a floating tourist population of 300-600 people, has one of the highest penetrations of rooftop PV, with 1.4MW of solar that produces more than its daytime demand.

norfolk supplyThis is despite the fact that the Norfolk Island regional council actually brought the installation of solar PV to a halt in 2013 with a moratorium designed to stop the “ad hoc” installations, and because it had no other means of controlling and managing the output.

Now, things have changed.

The cash-strapped administration wants to try and store the excess output of solar so it can reduce its reliance on diesel, cut its hefty electricity charge of 62c/kWh (unlike other islands, like King Island, it gets no subsidies), address the growing bank of “grid credits” given to those who produce excess power from their PV and perhaps allow more people who don’t have solar PV to add it to their rooftops.

Back in 1997, the council bought the last of its six second hand 1MW diesel generators, partly on the assumption that demand would grow. Instead it has fallen around 20 per cent, and it only ever uses two of the units at most, and outside peak times it uses only one.

norfolk mapThe council says the oversupply of solar is occurring each day “at all times of the year and not only in summer” when the sun is out.

Because the diesel generator needs to operate at a minimum 30 per cent capacity, excess solar output is shed via a 400kW load bank. Excess solar did not get a cash tariff, but grid credits that are now amassing into a considerable continent liability.

“The fuel savings from less usage of diesel in the daytime have not been matched by actual savings as, effectively, those PV consumers (generating more than they or their fellow consumers are using during daylight hours) are resulting in the need for Norfolk Island Electricity (NIE) to shed the excess in daylight whilst then burning diesel at night time to supply both PV and non-PV connected households at no/limited cost to the PV consumer.”

So, now it is is looking for battery storage as part of a wholesale review of its pricing structures, and as the administration comes under pressure from households that have not been allowed to install solar PV, but can clearly see it as a cheaper option than the current grid prices.

“This opportunity is for one or more persons or organisations to develop and supply a solution, or set of solutions, for Norfolk Island’s current problems of energy oversupply during peak periods of solar insolation and concurrent inability to store this oversupply for later use,” it says.

It is also inviting tenderers to think about other solutions, too, such as energy efficient lighting, demand management and electric vehicles.

In the past, the island has commissioned studies into wind turbines, biogas, large-scale solar, wave energy, and mini-hydro. But, for one reason or another, none suited. And all have since been sidelined by the rush to cheaper and more easily installed rooftop PV.

“Norfolk is no longer a “green-field’ site and with 1.4MW of consumer -wned distributed PV, has a different set of challenges,” it says. “Better utilisation of what we have now and integrating it with some other power/storage is a high priority.”

The other challenge the island faces is that the administration is cash-strapped – and one of the prime motivations for moving now is the growing bank of “grid credits” that it needs to address. The island is also remote, and it has difficult access.

norfolk duck

Energy experts often point to so-called “duck curves” in the California market and in Queensland, due to the growth of solar, but Norfolk Island is well ahead – in fact, it is already dealing with the excess of solar output over demand that is predicted for South Australia, Western Australia and Tasmania in the next 10 years.

Look at the graph above and contrast the dark blue dotted line across the top (load in pre-solar 1998) with the purple dotted line representing load in 2013. Note those dips in the early afternoon as the solar PV winds up in summer and winter (circled line).

Below is another representation, showing a cloudy morning in summer, but solar peaking well above demand, but having to be shed because the diesel generator can’t run at less than 30 per cent capacity.

(Unlike in King Island, where the hybrid project succeeds in switching off diesel altogether for long periods of time. Presumably, that is what the tender is about).

norfolk load curve

The island’s peak – last measured in 2013 – has not grown at all, and is around 1.3MW to 1.6MW, usually in mid to late morning as the tourist population have a “leisurely start to the day” and shower and have breakfast.

The evening peak is a little smaller, also based around “food preparation, dining, and entertainment and showers”, and there is no industry in the island to drive significant daytime load. And the declining population has resulted in a 20 per cent fall in demand over the last 15 years, along with the self-consumption of solar PV.

The total capacity of 1.4 MW installed distributed PV has since been estimated to generate an average of between 5,000 and 6,000 KWh per day (over a whole year) of which approximately half is estimated to be usable if returned to the grid.

This assumes 88 per cent shade free and a less than optimal installation. In common with many other jurisdictions, not all PVs have been installed with optimum orientation of solar. It is estimated that 50 per cent have been installed at optimum orientation and angle.

Expressions of interest are due in the first week of May.

This article was originally published on RenewEconomy sister site, One Step Off The Grid. To sign up for the weekly newsletter, sign here.

  

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  • Chris Fraser

    Wish them well. Their success and lessons learned could lead to more integrated networks on the ‘big’ island.

  • humanitarian solar

    Looks like it needs more solar, wind, storage and retire baseload generators. Looking forward to hearing how it goes for them.

  • Stan Hlegeris

    Why would showers have any effect on early evening demand? Surely the water is heated at some other time, such as during the midday solar peak. The water heaters simply need timers so they don’t re-heat immediately when people take their pre-dinner showers.

    • Bob_Wallace

      Time of use (tankless) water heaters rather than tank heaters?

      • Miles Howe

        That’s correct, where is the incentive to have a storage tank ?

  • Troy Hamilton-Irvine

    How about instead of individuals installing more solar panels, which arent needed due to the excess power already generated and instead let them install battery storage. During the day when there is too much power entering the grid an individuals battery storage recharges and at night when the load is required those battery storage units around the island supply the grid. Individuals should be allowed to charge batteries at no charge provided they supply the grid with that power when needed, which of course is wound back from their power supply bill, the same way that a solar installation does. This means that the cost of the storage is passed onto the consumer, whose investment is returned by what they can put back into the grid when needed. Ideally the ability for the plant to remotely have control over when the batteries store power and return power to the grid would be ideal. The island already has a substantial fibre optic network not being effectively optimised that may be able to be utilised to communicate with battery storage and even better if it could also receive real time updates from current solar installations. Its not that people want to put more solar panels on their rooves but rather to reduce and even eliminate their usage costs. I am not sure how the cost of battery backup compares to the cost of solar panel installation but this would/should be taken into account when considering the credits so that the system is fair, regardless of the installation of panels or batteries.

    • Miles Howe

      Allowing some consumers to invest in storage instead of generation is a good option and one that I have put to both the former Legislative Assembly and the interim council. Appropriate metering that would allow variable tariffs would also be important. Giving a feed in tariff equal to the retail price of electricity is crazy. And by the way NI has not contractual arrangements with any consumers who have pv panels. So just as they stopped consumers installing panels, they could reduce the feed in tariff to zero or very low and have an immediate effect on electricity use. Automation of load management would also reduce costs. Basically the solar roll out on Norfolk Island was flawed from the start. In a small place like Norfolk, grid level solar production would have been of benefit to the whole community not just the few.

  • Brunel

    My profile says I live there!

  • lin

    A few electric vehicles set up to use surplus and feed back in times of demand could balance things up a bit. It will be interesting to see how long it takes them to go 100% renewable.

  • Ian

    What is the base load generator that it cannot be switched off in the middle of the day? Maybe that is the problem. 40% of the peak load is drawn at the minimum load. Why is that? Does this reflect water heating or refrigeration or street lighting. Hot water storage is a cheap way to store energy. And a large proportion of water heating can be converted to heat pump or solar thermal heating or both with hot water storage and the midday solar excess used to supply that load. Street lighting can be changed to LED lights at a reasonable cost. How is water reticulation and sewerage provided? A header tank to provide water pressure in the night with sufficient storage of water may be an option to reduce nighttime use of electricity. Time of use type tariffs to encourage daytime use of electricity and battery storage would be very useful.

    I suspect in their minigrid way they are just like our incumbents, hanging on to the old baseload generators.

  • Matthew Wright

    The cheapest addition is to oversize the existing inverter capacity with additional solar panels so there isn’t anymore midday solar added but solar added towards the morning and afternoon which would be clipped during the daytime. Going from a bell curve to a table top of output. 300-400% should be the target and is economical when compared to 60c/kWh power (ie 300% oversizing is 33% clipped therefore the cost would be around 5-10c/kWh to generate a unit. 400% oversized PV would have an equivalent cost of 10-15c/kWh approx. Even if 50% is curtailed (sent to dumpload) its still a hell of a lot cheaper than 60c/kWh power from the islands generators. After this much lower cost solar oversizing additions are added, then and only then should batteries be considered. The other thing they should consider is grid limiting. Where larger inverters are allowed to be connected and as local loads fire up the inverter dynamically adjusts to meet those loads but at other times the output is clipped to what is acceptable input to the grid.

    • Ian

      Yours is a good point, but for 4 hrs in the middle of the day their ‘baseload’ generator is running, whilst an almost equivalent amount of solar goes to a waste load. The solar is installed on people’s houses and the FF generators in the council powerhouse. You would wonder how much the problem is more social and economic then purely engineering.

    • Greg Hudson

      Another option might be pumped hydro. Use the excess solar to pump the water uphill, and use it in the evening / morning when it is needed.

    • solarguy

      Looking at their demand profile shows 2 things. They still don’t have enough solar, but demand is high during the night so they will need storage.
      There is no other conclusion, apart from perhaps a wind turbine or 2 in addition.