Posts by Moz
Last ←Newer Page 1 2 3 4 5 Older→ First
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to David Haywood,
We are now effectively getting free hot water to the value of over $1,000 per year
We use a total of about $200 of hot water a year, which drastically affects the value of any of these systems. At 8c/kWh off peak and 4-8kWh a day of consumption, it was hard to justify $50 worth of extra insulation for the tank, let alone $5000 for a heat pump one.
We also have problems with the interaction between PV and hot water, in that you either run it off peak at 8c, or on peak at 30-80c with PV input, you're not allowed to have both off peak and local PV heating the water.
For our granny flat I spent a while playing with numbers and talking to installers, and in Sydney it's much, much cheaper and easier to go solar thermal hot water with grid-tied PV to whatever level you can afford. The feed-in tariff in NSW is whatever the power company wants, which seems to be about 5c. So the margin you're making when comparing PV+heat pump to off peak resistive is only 3c/kWh... you have to be using a lot of hot water to pay for $5000 of capital at that rate. Or about $2000-$3000 for solar thermal. I decided that I'd rather pay for solar hot water mainly for green hardline and resilience reasons rather than the largely imaginary cost saving, and ditto the extra $2000-odd to get an inverter that will work without a grid present.
An important caveat is that all those costs are valid at time or research only - they change, sometimes significantly, from day to day. Currency changes, new products or new versions of old ones, government whims, they all make life exciting.
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to Lilith __,
One point to keep in mind is that most of NZ's population lives in Auckland, so there is a big difference between "most people" and "most land/most towns/most houses". If you restrict discussion of solar to "Auckland and points north" the numbers look much better. Not good, but better.
why does everybody not have hot-water-heating solar panels
Because almost all solar water heaters lose energy on cold cloudy days, and much of NZ's land area has those for half the year.
Now, some pointed remarks. The ideal angle is somewhere steeper than your latitude, so for NZ that means 45 degrees. Which doesn't really go with most rooflines. The one pictured will largely stop working at the start of winter, even on sunny days - it's just not going to collect enough sunlight to be useful. A more sensible setup won't really peak at all - it will heat all the water as hot as it's allowed to, for more than 70% of the year. But for most of NZ that means 2-5 square metres per hundred litres of tank which is ridiculously expensive.
You want to over-steepen, so the orientation is best in winter and in summer when you more collector than you need the orientation isn't ideal... but that doesn't matter, because 3x the area you need working at 80% of potential... is still 2.4x as much collector as you need.
There's a circular process at work too - they don't make sense, so there aren't many of them, so there are no skilled, experienced solar hot water system designers or installers, so most installs are sub-optimal, which means the economics are even worse than expected, so people don't install them,
In Sydney it's the other way round - there aren't a lot of heat pump hot water systems, the ones we have are mostly imported, few plumbers know much about them so it's hard to get one fitted, so few people install them. It's getting better, but it still is not great. But then, we also have the opposite "problem" to NZ - solar hot water systems work well, are cheaper than electric, are not powered by coal, and there are a lot of options from a lot of installers.
-
Polity: Australian election: Dust and Diesel, in reply to Rich of Observationz,
How? Each list is published, the people vote for the list as a whole. If you don't like a list, don't vote for it, there are plenty to choose from.
The legal system and common sense are not even second cousins, they're almost different species. Both use language to express reasoning, but that's about where the resemblance ends.
My understanding is that votes must be cast for a specific person, not for a list of people. So STV is allowed because I vote 1:Bob, 2:Sam, 3:Chris, each preferential vote being for a specific individual. In the senate the rules are different, since there have been multiple senators per electorate (state) right from the start. But with a list system I am not voting for a person, I'm voting for 1:the list made by party X, 2: the list made by party Y, and so on. That is considered too indirect.
-
Polity: Australian election: Dust and Diesel, in reply to Rich of Observationz,
a mayor/leader elected by councillors.
In Australia that leads to excitement as different factions/parties make and break deals with each other over who gets to be the mayor and for how long. But it still beats the Auckland mayoral contest.
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to Rich of Observationz,
If your local substation trips, then a small number of inverters will try and drive all the local loads
No, no, no, that would be insane and dangerous. I can't imagine anyone certifying an inverter that does what you're suggesting. The idea is that you mechanically switch so you're isolated from the grid and the "island" is your house. Modern inverters all electronically switch, but to get an install signed off you need a separate mechanical switch.
The mechanical switch is so that electricity and emergency workers can see easily that this is the case, and smite you with fire if you bypass that and back-feed a dead grid (which probably wouldn't work, but you still don't want to be the one holding the wire when it happens).
My somewhat simpler plan is to use a UPS-style system: grid feeds house, UPS plugs into wall and charges battery, solar also feeds UPS/batteries, I plug stuff into the UPS. Most small off grid systems have a generator input what can also run off a single phase socket, to look at it another way. But there's a couple of companies in Oz doing UPS-sytyle systems for on-grid urbanists like me. Largely as a regulatory hack - in OZ it's almost impossible to get any feed-in payment at all if you have batteries, and almost as impossible to be allowed to buy off-peak power if you have batteries (yes, they are that dumb). But a plug-in system doesn't count (otherwise even a battery backed alarm clock would trigger their "no grid connected battery systems" clause)
-
Hard News: DNC 2016: Beyond weird, most…, in reply to Deborah,
I want both: the ideals, and the on-going pragmatism to work with people to get elected and actually get the opportunity to do things.
And the Democrats appear to be getting both, with Sanders there explicitly to push the envelope and get ideas on the table, and Clinton to run the middle of the road path and win the election. Hopefully by a landslide, because while some might deride Saunders as a wingnut... on the other side they don't appear to have wings, just nuts. The scary thing with the media narrative is that they're trying to reinforce and normalise the idea that there's a big mass of Sauders-Supporters-for-Trump voters. I don't believe everyone in the US media is too stupid to see that.
Rob, I've seen numbers that suggest the USA has been "not in active conflict" for about 10 years since it was founded, most of those more than a century ago. One of the problems of running an empire is that there's always someone, somewhere, who's angry with you.
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to David Haywood,
Photovoltaics (grid-connected) don’t make much sense from an energy engineering perspective in New Zealand either
Well no, when your existing electricity supply is largely renewable the maximum possible GHG savings are negligible. I feared for a second it was another of the misleading calculations that we see so many of on sustainability.stackexchange, but nope. In Australia, on the other hand, PV very directly displaces brown coal (or carboniferous earth to give it the proper name... 40% or more of the "coal" remains after burning) and it's hard to get a bigger win than that.
One thing that local generation does is increase resilience. Or it should.
IMO every single inverter should capable of islanding (operating when the grid is down), and have a large, mechanical switch on the front indicating whether it is or not. Ditto the install. Our system already has labels to encourage emergency services to turn it off before getting involved, and the extra step is from "this might be live so you should treat it as though it is" to "this is slightly more likely to be live, so you should treat it as though it is".
At least with passive hot water systems they will work as long as there is sunlight and water. If you have a pumped setup, though, it needs power. See above "capable of grid-independent operation" step. I am in the process of designing a sleepout that will have a solar-powered UPS which is an off-grid setup in all but name. Mostly because it's not much more expensive than getting power to the sleepout. Hopefully my free, ex-demolition coolstore panels will arrive in October and I'll be able to start construction.
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to Bart Janssen,
Two phrases I find myself saying more and more often are {1} and {2} and {3} and {4: mathematically challenged}
QED?
-
And the media narrative will focus on finding and amplifying the "Trump over Hillary" BernieBros, because anything that can help tilt the field towards Trump is good. Sorry, I mean "conflict and excitement means clicks".
On the other side, I don't think this will actually be the incident that makes politicians start caring about reinforcing electronic privacy rather than stripping it away, but I hope it will help.
-
Southerly: A Tale of Two Iceblocks: Part…, in reply to linger,
I may be slightly biased, as I’ve personally walked away from a few cycle vs. car [and subsequent tarmac vs. head] crashes, partly thanks to wearing a helmet.
Helmets are another population issue, not a personal one. It is almost certainly true that if you are someone who will ride regardless, the helmet makes you safer. Cycle planners have the "four types of cyclists" and it's the 50% in the middle who are "interested but concerned" that matter for the helmet debate. If half the crashes involving the the 10% who already ride can be mitigated by helmets that's kinda nice... but if it comes at the cost of another 10% of the total not riding at all, that's a net loss. Unfortunately the evidence is that mandatory helmet laws have exactly that effect. The overall result is that more people die or suffer injury/disability by being fat and unfit than are saved by not getting head injuries. But that benefit happens at a population level, while some of the benefits of a helmet happen at a personal level (the others happen at the idiotic "fewer cyclists in my way, more money for roads" level that only people who perhaps would have benefited from wearing a helmet can understand).
Amusingly, more brain injuries could be prevented by "shower helmets" or pedestrian helmets in general, than by bicycle helmets. Buy a non-slip shower mat, it'll do you more good than a bike helmet.