When I first arrived on Stewart Island back in ’69 my Forest Service cottage had a “Shacklock 501” coal range for cooking, hot water and room heating. My lights were “Tilley” lanterns. The coal I had to carry around 100 metres and up hill. Halfway through the year the Department installed a 1.5KW air cooled Lister diesel gen set. I had to go down to it’s little shed to start it, but I could turn it off from inside. I thought I was made. Even though 1.5kw wasn’t good for more than lights …. even a jug needs around 1.8kw. Our first home in main road had a 2.5KW water cooled Lister, but fully automatic so first light on starts, and last light off stops the plant, But we still cooked on a good old Shacklock 501, but it had a modification which allowed it to run on diesel. No coal and ashes, but the unit required careful cleaning every month. Being ever thrifty (my grandparents were both Dutch & Scots, which Iris says is a very bad combination) I modified the generator to pump the cooling water to the house where we used it for heating. And we changed the cooking to gas. 2.5Kw meant we could run a microwave, but only after turning the fridge and freezer off. When we moved to 11 View Street, where we are now, it was back to a coal range, but out generator was now a 3kw, but air cooled, so no waste heat to harvest. Then the community power scheme was built, and so no generator, almost unlimited power and on 24/7. We had a 2.5 tonne blast freezer for our fishing business, and again harvested the waste heat from the condenser. Energy is expensive, so wasting doesn’t make sense. When we rebuilt our home to make “Sails Ashore” we decided that we needed a central heating system for our guests comfort, and so we installed a diesel furnace, which also supplied domestic hot water, and we threw out the coal range in favour of all gas cooking. All very good, but quite expensive, and our energy bill was around $900 per month (diesel for central heating/hot water, LPG for cooking, electricity for everything else) People asked us about solar for both hot water and/or electricity (PV). Some many years ago back when we were Qualmarked we went for “Enviro Gold” status, and energy sources were a potential stumbling block. I did a considerable amount of research, and cutting to the chase, the best use of our dollars was not in alternative energy, but in energy conservation. But technology does improve and I started to look at how we used energy, and the sources. Cooking was my first focus. We were spending around $20 per month on LPG, and I wondered how changing to Electricity might pan out. We pay around $0.60 per unit, and that worried me a bit. But then I had a look at using an Induction Cooktop. And found many articles suggesting Induction would be a good choice. So I purchased a really cheap plug in induction plate. Cost $150. I very carefully measured our gas use for a month, and then shut our gas hob off, and cooked for a month on that single plate. At most we were $10 adrift on the induction. So we took the plunge and installed a Bosch 4 zone hob. A bit of rewiring and a bigger breaker on our switch board and no way would I willingly go back to gas. Our power bill is no different to our historic average. The kitchen is far cleaner, as the range hood doesn’t have to cope with the unused waste heat that is a function of all indirect cooking. No moisture from burning gas, and because I can much more easily control the amount of heat, and as it’s better spread across the cooking utensil I don’t get stuck pot bottoms. The level of control is many time more precise, so really easy to adjust for simmering. The top of the unit gets no hotter than the pot so I can wipe up spills as they occur, and things don’t get baked on. Remove the pot, and it shuts it’s self down…. magic!!. I doubt our insurance company will reduce the premiums, but without naked flame cooking the risk of a kitchen fire should be much reduced. Our gas oven was getting past it’s use by date, so it got replaced by a Bosch double electric oven. And again it has just been a win win change. It’s quicker to heat. 30 minutes on gas to get up to temperature for doing the breakfast croissants vs about 4 minutes for electricity. And the waste heat isn’t vented into the kitchen, because unlike the gas which HAS to vent, the electric oven actually keeps the heat in, so MUCH more efficient. Yes our power now seems to be around $5 per month higher, but then no gas saves $15. So $5 on the plus side of the ledger. Not much, but a much better kitchen environment.
Now something of a collectors item, but NOT something I look back on with nostalgia
Electricity, Stewart Island Style
up to 2000 litres of diesel per day
Our little test top on the left, and my new favourite toy … Bosch Induction Cook Top
I always say to our guests that Stewart Island runs on diesel, and that’s more or less true. Some years ago a trial on PV economics showed very conclusively that it just didn’t work with the technology available then. The purchase cost very high, and so far south, and with our high number of cloudy days the output was abysmal. But last summer two guests filled us in on their PV installation. They lived north of Auckland, and so my immediate response was there was a world of difference between the availability of solar radiation between there and here. But they explained that the output didn’t drop that much even on cloudy days … efficiencies have improved enormously in recent years, and the cost per watt output had dropped significantly. To go more or less completely off grid we would need to generate a minimum of 20 kwh (kilowatt hours) each day to be self sufficient, and probably to be able to store the same amount. So I built a small solar logger. Pretty basic, it’s a 10 watt pv panel, directly feeding a LED, with a logger recording the voltage. I record voltage over 9v as full output, and below 9 as no output. As I said pretty basic. Last month we had two periods when we would have “run out” of storage had we been completely off grid. A small gen set would cure that of course, but Iris says “over her dead body”, so probably for a year at least we would stay connected. In the summer of course we would massively over produce our requirements, and we could sell back to the local supplier. At that stage I didn’t know what they would pay, but I suspect probably not much. We currently spend around $11 per day for diesel for our central heating/domestic hot water. So I did a test on our central heating, and found we can run our kitchen radiators for 3 hours before the 300 litre cylinder goes cold. Then I tested an 1800 watt electric jug and found 7kw would take around 6 hours to heat 1000 litres to just under boiling. So a total of 1300 litres of hot water would be close to a days requirements in winter, and as our diesel fuel usage seems more or less the same summer and winter …. guests need showers, and not much heating, and in winter less showers for just Iris & I. but more central heating. So probably better to use excess electricity to produce hot water than sell to SIESA (the local power supply authority) at a depressed price. The local school has just commissioned a 60 panel array which is probably around 15KW max output. And Kath, the head teacher seemed very happy with the output, when I was talking to her, and happy as well with the surplus they were selling to SIESA.
Our local power supply is a subset of Southland District Council (SIESA). We needed to know what, if anything they they would pay us for excess power we produced. So I phoned them on June 30th and, in their normal high efficiency mode it took them just 3 weeks for a response, and then only after several prompts, the last of which was very terse, they tell us we’ll get $0.20 per unit ….
Don’t talk about it… Do It !!
So we “bit the bullet” and asked Shane Brown from Tansley Electric to come across from Invercargill and “measure up”.
It’s all go. I have just completed a small shed to house the electronics and also the LI batteries. We could have put all this in our garage, but LI batteries have been known to go on fire, so discretion seemed worth the effort.
The 14 panels (7 kw output) have arrived, and Tansleys will be here to install them in the next few days. Unfortunately we won’t get the electronics for a month or so, as we’ve asked for a slightly more hi tech version of the standard inverter/power grid share. Ours will prioritise with house consumption/battery charge first priority, with surplus fed into hot water (which will at the same time switch our diesel furnace off) and only surplus beyond those two will be sold to the local power supplier. Thinking about the $0.20 per unit it makes much more sense to forgo much that small payment in favour of reducing our diesel consumption. The system and our roof layout will allow for a doubling of panel size if we need to in the future. We are also installing two 5kw inverters, partly “belt & braces” but also this will be able to cope with our full electric cooking load.
Our Little “Battery” Shed.
There are worse carpenters than me, but I’ve never met one, so a kitset from Trade Tested in Auckland.
Iris is complaining that our back lawn looks like a construction site. But I tell her that’s exactly what it is.
It will get worse, as I have to trench both the lawn and the cobbles to bury all the cables
The covered pallet is the 14 solar panels