Welcome to Stewart Island & Sails Ashore +64 3 219 1151 tait@sailsashore.co.nz

Community Power on Stewart Island

Since we’ve commissioned our off grid power supply at Sails Ashore I’ve had several Islanders ask how it was going. Understandable in view of the recent worrying sharp increase in the cost of diesel fuel and what that will inevitable mean to power charges. And a couple of days ago I came across this article from “The News Room”. It got me thinking about our own experience with Photo Voltaics (Solar Power or PV) and battery storage, and so decided to put my thoughts down, and send them to the Newsroom as follows.

Good Evening from Stewart Island

I read the subject item with some interest.
We have just gone completely off grid  see https://sailsashore.co.nz/sails-ashore-and-the-stewart-island-environment/  And as you will see from this link we have also installed 5kw of panels on Kowhai Lane Lodge on a grid tied system. 

Electricity from the local authority is diesel generated. Monthly tariff is $95 per connection, and power $0.61/unit. We did so for Kowhai Lane Lodge  on the understanding that as per the attached PDF that SIESA (Stewart Island Electric Supply Authority, wholly owned by Southland District Council) would pay $0.20 per unit that we supply to the grid.

SIESA Charges taken from P27 SDC Charges webpage

My understanding is that the $0.20 is about the diesel component of the per unit tariff.

I have just been informed that SIESA intend to reneg on that agreement in either June or July. Which makes something of a nonsense of protestations of clean and green from local and central Government as by removing the payment they effectively discourage PV

Megan Woods offered the community some $3.16 million for investment in renewable energy. But this was apparently locked into wind power, and for a variety of reasons was rejected.
see links :-

  1. ……MBIE Wind Power Investigation
  2. ……Stuff Wind Farm Shelved
  3. ……Stuff Wind Farm Opposition
  4. …… Researcher Proposal

As an aside one wonders why Woods restricted the grant to windpower alone.

It occurred to me that had that money been made  available to property owners as a loan to install PV, repayment with interest at the rate of inflation plus (say1%), then council would have been able to fund some 1167 kw of panels, and that assuming the same $/kw as we spent on Kowhai Lane. And I would be prepared to bet that spending $3.5 m would have generated a much better $/kw value than spending $15k. I would envisage council bulk purchasing panels and gear, and contracting installers, and loaning the cost thereof to the property owners… economies of scale

The beauty of the loan scheme is that Council (SIESA) actually does not spend the money, they loan it. So the capital asset is always there, and it, and profits can be used to add more supply, and/or batteries to utilise excess production. 

In our own case at Sails Ashore, we have 10kw of panels and 24 KwH of Li storage, of which we can access some 80% or around 19kw. We expect to need back up diesel “Top Up” maybe 6 to 10 hrs per month over the winter, and around 3 hrs per month over the summer. Our home is all electric cooking (induction range hob). Once the batteries are full at present we manually direct excess electricity into heating our domestic and central heating water, which to date is cutting our heating diesel usage in half. Over summer we expect much better than that. Once this transfer is automated this figure will improve.

We commissioned our 7 kw array in Early November, and added a final 3 kw in Mid March. Over that period we have produced/consumed some 3000 Kw/H of electricity with a value of $1830, and have saved some 400 litres of diesel in our hot water system. Electricity production/consumption will improve when we replace the 3kw hot water heating element with a 4 kw one. It should also be noted that the system actually was capable of producing more the the 3000KwH noted above. Production is limited to what we actually consume.

A question I’m always asked is “What about cloudy days ??”
As I type this it’s a really dark day, and at almost 1 kw we are still producing much more than we are using.
An hour of bright sunshine will cover us for over night usage
And if that doesn’t occur then an hour and a half of generator will achieve the same.
Last month we ran our backup gen set 3.5 hours.

I discussed all this with our local ward member, who wants to set up a solar farm. In my view this fails the economics test in the following way

    1. First cost is buying land, where as encouraging consumers to purchase through loans costs nothing in siting costs …. Roofs are already there
    2. Reticulation costs of transmitting say 1000 kw into the local grid will be considerable.  Installed on a house roof costs nothing in reticulation, as it is already in place. And that 1000 kw is at $15k per 5kw. Economies of scale would be much better than that
    3. Maintenance ….. land will need to be keep mowed and tidy to ensure maximum exposure of panels to the sun. Especially important as if one panel in a group is shaded, all in that grid drop output to the lowest denominator, The house holder will keep his or her panels clean at no cost, as failing to do so will reduce their dollar return
    4. Economically if SIESA spends the money on a solar farm they can only do it once, and all they have is an asset. If they loan the money, they always have the original “seed money” albeit loaned out, and can grow that investment.

I have done a fair amount of modelling to support our decision to go off grid, and freely accept that we are a complete “loss” to the community power scheme. But a grid tied community just makes so much sense, as it is environmentally sound and also makes each consumer co-owners of the Island power system. And perhaps most importantly goes some way to insulating the community from the ever rising cost of non-renewable energy

I hope all this makes sense, and am happy to discuss this with you.

Regards…………. Peter

Local Thoughts

I’ve been putting my ideas to some of the locals on the premise of ……. If SIESA offered you loan money to install 5KW of PV,  grid tied on your roof at a total cost of $15K (using Kowhai Lane Lodge figures but more likely $10 to 12k) paying you $0.20 per KwH you returned to the grid would you do it.

All bar two were emphatically in favour.
One of those wanted to look at the figures, and one was in favour, but not for them as their roof was heavily shaded most of the time.