Hard News by Russell Brown

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Hard News: Going solar?

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  • John Morton, in reply to Russell Brown,

    Choosing solar water heating now over PV later might matter if you where using up all your roof surface area (you're not), and there is a significant difference in efficiency between the two — PV is about 15%; I don't know what solar heating is, but it's unlikely to be much worse.

    I found this helpful:

    http://physics.ucsd.edu/do-the-math/2011/09/dont-be-a-pv-efficiency-snob/

    Wellington • Since Mar 2014 • 4 posts Report Reply

  • Alfie, in reply to Stamper Stamp,

    Maybe green energy isn't a reality after you have looked at the whole picture - a bit like the bio-energy fiasco.

    You mean the rest of the world has it wrong? Germany is going solar big time, the UK is heading for 10% of homes, AU is a very solar-friendly country and the US is putting up panels like there's no tomorrow.

    You may feel that electicity prices will drop in the future, but I can't see that happening. I did the figures before installing solar and I'm very happy with a 10-12 year payback. My system has already halved my power bills and the panels are guaranteed to be producing 85% efficiency after 25 years. That's 15 years of almost free power and that certainly works for me.

    Dunedin • Since May 2014 • 1388 posts Report Reply

  • BenWilson, in reply to Alfie,

    You may feel that electicity prices will drop in the future, but I can’t see that happening.

    I can. But it will be solar supply causing it. Every one of you guys going solar is good for me too, because that's one less person competing for the hydro, and even some increased supply when it's extra sunny.

    Auckland • Since Nov 2006 • 10641 posts Report Reply

  • Raymond A Francis,

    Don't piss around put in one of these big boys
    http://www.amusingplanet.com/2013/08/the-solar-power-towers-of-seville-spain.html
    We went the vacuum tube way a couple of years ago when upgrading bathrooms and water system, it is great. A friend who put in a wet back as well has not paid a heating bill since
    There is talk that electricity prices may fall but that is not the way of the world

    45' South • Since Nov 2006 • 576 posts Report Reply

  • Chris Waugh, in reply to Raymond A Francis,

    Don’t piss around put in one of these big boys

    They've been building something similar in Yanqing County in Beijing's northwestern corner (kinda to Beijing what Middlemarch is to Dunedin, I guess), except there hasn't been any visible progress on it for a while now, at least not to this layman's eyes. It was my impression that solar thermal was hideously inefficient, though. Still, they do look cool. Deeply, fundamentally, sci-fi comic-ly cool.

    Wellington • Since Jan 2007 • 2401 posts Report Reply

  • Jeanette King,

    Since 1982 I have had solar panels for heating hot water in two houses. On both occasions the installation costs were mitigated by the necessity of replacing the hot water cylinder anyway. The solar hot water heating is supplemented by electricity. In summer I turn the electricity option off. For the rest of the year I mainly have an 'auto' option where the water is heated up by electricity for a few hours before we wake in the morning for showers. That's enough for the two of us. Certainly, since it's often stated that water heating costs count for up to half of power bills, our power bills are much lower than other people's. In other words, it's a great investment, particularly so when you are need to replace the hot water cylinder anyway. The big option is whether you have a mains or low pressure system. I'd highly recommend talking to David Haywood who has expert knowledge in this area.

    Ōtautahi • Since Oct 2010 • 43 posts Report Reply

  • Chris Waugh, in reply to Alfie,

    You mean the rest of the world has it wrong? Germany is going solar big time, the UK is heading for 10% of homes, AU is a very solar-friendly country and the US is putting up panels like there’s no tomorrow.

    Add China into the mix, where solar water heating is extremely popular, including in north China, where winters make Central Otago seem mild by comparison. There are even solar public bathhouses in the countryside.

    I can understand people debating the comparative merits of various set-ups and systems and their suitability to different households in different climates, but I don't get Stamper's objections. There are installation and maintenance costs, of course, but otherwise it is, as you say, free energy. What's not to like?

    Wellington • Since Jan 2007 • 2401 posts Report Reply

  • Lucy Telfar Barnard, in reply to BenWilson,

    Which would, incidentally, be fair – passing on the real cost, rather than slipping it into the usage charges which fluctuate with the price of power.

    It would be “fair” in that people would be paying their equal share of the cost. However, the current arrangement is kinder to low users and those who limit their use due to fuel poverty, and also does more to encourage energy efficiency.

    Wellington • Since Nov 2006 • 580 posts Report Reply

  • Moz, in reply to JonathanM,

    Folks - if it was a 'no brainer' to move to solar - every one would do it; instead we have the arguments for/against for trying to save planet/energy/money.

    The problem is that there's multiple levels that the argument is taking place at. Purely financially, and for a single homeowner it's currently marginal in Australia (given the current subsidies to coal, oil, gas and pv) and similarly in NZ. If you assume a grid connection it becomes marginal in NZ and worth while in much of Australia. But there are a lot of arguments like the above about whether people should be allowed to do it and how much they should pay and be paid. And it's money that (for most people) would be better spent insulating their house to reduce demand and increase health and comfort.

    At a neighbourhood level it's worth while financially for both countries, but legislatively it's impossible. The fees and regulations for grid operators are designed for national or state level operations, and they just don't work even for a new subdivision, let alone an existing one. Which means that until it's financially overwhelming it's not going to be possible to bypass the national; grid. It's illegal to throw a cable over the back fence and sell power to your neighbour, in other words.

    At a national level it's a whole different ball game. Technically NZ should already be at 90% renewable, as we were in the 1980's. But politically? That's just not an option. The question is more whether we will destroy the economy to build more stranded assets (fossil generators), or see it grind slowly to a halt as foreign owners let assets decay. I can't see the current brown parties even allowing a big solar generator to be built, let alone change the subsidy model away from fossil fuels towards solar. Although again, technically a CSP+storage plant in Northland would work very well. It would effectively be a combination peaking plant and baseload, because you can "spend" the storage whenever you like. So if there's a peak you can dump the storage to service it, but if there's not you can bleed it out overnight ready to charge up the next day. The political consequences of a major job-producing investment in Te Tai Tokerau would be interesting as well.

    In Australia Beyond Zero Emissions did a major study showing that a transition to 100% sustainable electricity by 2050 would be profitable even with unfavourable assumptions. That was later verified/reproduced by the Climate Change Authority. But right now both NZ and Australia have governments committed to favouring fossil fuels over sustainable ones, and they are the people who control the economics.

    Sydney, West Island • Since Nov 2006 • 1200 posts Report Reply

  • Moz,

    Actually, from a completely different point of view: right now, if I could, I would cheerfully invest in a company or do it myself, if I could buy panels to put on someone else's house. The economics are there, it's just a difficult thing to do in practice because the margins are not so large that you can afford a string of profit-takers in the middle (and the rules are so unstable in Australia that the main risk would be sovereign). One issue with "community solar" in Sydney is that every time a group identifies a site that they could put panels on, they approach a supplier company and the site owner... and in many cases where the site is viable those two do a deal that cuts out the neighbourhood solar scheme. So yes, it is profitable.

    Sydney, West Island • Since Nov 2006 • 1200 posts Report Reply

  • Stamper Stamp,

    Folks - if it was a 'no brainer' to move to solar - every one would do it; instead we have the arguments for/against for trying to save planet/energy/money.
    It you have to argue - it is obviously NOT compelling.
    So - are we going to save planet/energy/money - or are we just going to "feel good" ?
    Maybe green energy isn't a reality after you have looked at the whole picture - a bit like the bio-energy fiasco.

    Auckland • Since Feb 2014 • 27 posts Report Reply

  • Steve Barnes,

    I would not recommend getting a solar hot water system from a Power provider,
    You will find is that once the power company knows you are not using electricity for water heating they will up your unit cost. One reason for this is that they use ripple switching on water cylinders to balance the grid, in times of low use they can turn on your tank in times of high demand, they turn it off, you won’t really notice this as your cylinder is a hot water storage system, not a demand one. The other is that they have to make as much profit for their shareholders as they can.
    Another reason is the way the system works. The kind of system that a power provider will install is one that keeps your existing tank for storage, so far so good, but they will also tell you to leave the power on the cylinder in case of days of low solar input, cloudy days. This causes problems, especially if you are not a large user of hot water, when the cylinder temperature is higher than the panel temperature you will get loss back up to the roof panels through convection.
    I would suggest a hybrid system of gas hot water on demand, which is far cheaper as you are not storing hot water at around 55c and solar preheating to your existing cylinder which can and will reach quite high temperatures on sunny days, in this country in summer I have managed to boil water in a roof panel in less than 30 mins. (considering we get over 1Kw per square meter in average sunshine, even in winter, this is not surprising)
    With a thermostatically controlled system pump, switching @ 55c feeding a 185 ltr cylinder in sunny weather your water will heat faster than using a 2Kw immersion heating element. Run that through an on demand gas water heater and the thing won’t even fire up unless the water in the cylinder is lower than 60c (in theory at least) so on sunny days you use virtually no gas and on cold cloudy days you will have constant, limitless hot water.
    As for the price you were quoted, jeeze. The import price for these units is less than a couple of hundred bucks.

    As for PV systems, now that is something I know a lot about should anyone want to know.

    Peria • Since Dec 2006 • 5521 posts Report Reply

  • steven crawford,

    As for PV systems, now that is something I know a lot about should anyone want to know.

    I don’t know a lot, but I know what I like:)

    One of the expensive parts of the PVs, is the connections between cells. That’s why science geeks have developed a modified inch jet printer system to get those cell connections down to a micron or two. Which is plenty fat enough.

    Atlantis • Since Nov 2006 • 4336 posts Report Reply

  • Josh Petyt, in reply to Jeanette King,

    The big option is whether you have a mains or low pressure system

    Generally speaking most installations are mains pressure today.

    Japan • Since Apr 2014 • 44 posts Report Reply

  • Moz, in reply to Stamper Stamp,

    Maybe green energy isn't a reality after you have looked at the whole picture - a bit like the bio-energy fiasco.

    You mean like the 80%+ hydro that NZ ran on for 50-odd years last century?

    Sydney, West Island • Since Nov 2006 • 1200 posts Report Reply

  • James Green,

    If you are interested in cutting your hot water energy costs, and showering is a big consumer of hot water, you should do this first: drain water heat recovery. Essentially, it's a heat exchanger that goes in the waste pipe below your shower, that uses the heat from that water to pre-heat the cold (either for a cylinder, or straight back to the shower). I wrote a long post about it here. The Napier company sell them for under $500, and they cost about $200 to install, and confer about the same savings as a solar system.
    I just don't understand why we are still talking about solar*, and not this. Except I guess drain water is yucky.

    *Of course solar is still a good thing, but if you put one of these in, you can install a smaller system.

    Dunedin • Since Nov 2006 • 703 posts Report Reply

  • James Green,

    $650 installed
    Similar savings to solar

    Reference

    This isn't spam, I'm just so frustrated that this isn't in the frame. Basically the only people drain water heat recover isn't good for is if you have a new house with a concrete floor and your shower drain is inaccessible. Or if your house has exceptionally restrained showerers.

    Dunedin • Since Nov 2006 • 703 posts Report Reply

  • DexterX,

    On the basis that you roof is corruagated iron - With placing panels on your roof you have to be mindful of the spacing of the purlins - and it is best to put extra purlins around the area where the panels are to be installed to give support when the installers are walking around your roof and to enable the roof to hold the weight of the panels. The panels need to be sitting up of the roof to be efficient as shown in the youtube clip on the solar energy site.

    If the panels follow the line of the roof what happens is that grim builds up behind the panel and as the rain in Auckland has an acidic ph value – this grime is acidic and will eat away the roof sheet – you will have holes that you can’t get to because you have a solar panel in the way.

    If the panel is sitting up properly off the roof then the rain should wash away the grime – you should also give the area a soapy wash say every six months.

    With the pipes that penetrate the roof sheet they need to be flashed out properly often you see several pipes coming through one rubber boot – this is wrong – the best option si to run all the smaller pipes through a large pipe /ducting arrangement that passes through one rubber boot – of the correct size – and that this should have skirt flashing.

    This is what the future is going to look like – the solar panels are the roof.

    For existing house the panels will become a lot lighter than the massive boxes that go up now.

    Auckland • Since Nov 2006 • 1224 posts Report Reply

  • Rich Lock, in reply to Stamper Stamp,

    Folks – if it was a ‘no brainer’ to move to solar – every one would do it; instead we have the arguments for/against for trying to save planet/energy/money.
    It you have to argue – it is obviously NOT compelling.
    So – are we going to save planet/energy/money – or are we just going to “feel good” ?
    Maybe green energy isn’t a reality after you have looked at the whole picture – a bit like the bio-energy fiasco.

    Solar power in Germany: http://en.wikipedia.org/wiki/Solar_power_in_Germany The article quotes 35% but I read somehwere recently that they topped 50% this year.

    Solar power in China: http://en.wikipedia.org/wiki/Solar_power_in_China

    Solar power in India: http://en.wikipedia.org/wiki/Solar_Power_in_India

    Solar power in Australia: http://en.wikipedia.org/wiki/Solar_power_in_Australia

    And according to this article link text, "the wholesale price of electricity in Queensland fell into negative territory" for the first time. In a country that generates a tiny fraction of it's electricity from solar.

    2 million Peruvians will soon have free solar power http://grist.org/list/perus-poorest-will-soon-have-solar-power/

    And here's a map that shows much much of the surface of the entire world we need to cover to supply all our energy needs: http://www.iflscience.com/environment/how-much-room-do-we-need-supply-entire-world-solar-electricity

    There is no argument. It's over. Solar won. The only 'argument' is how we best circumvent passive and active social and establishment resistance.

    back in the mother countr… • Since Feb 2007 • 2728 posts Report Reply

  • David Haywood, in reply to Stamper Stamp,

    Folks – if it was a ‘no brainer’ to move to solar – every one would do it; instead we have the arguments for/against for trying to save planet/energy/money.
    It you have to argue – it is obviously NOT compelling.
    So – are we going to save planet/energy/money – or are we just going to “feel good” ?

    What an extremely strange comment.

    The biggest problem with (non off-grid) residential energy systems in NZ is that the payback period is usually a bit longer than the period that we own a particular house, e.g. payback period is seven years and on average we buy/sell houses every six years.

    That means the next person gets all the savings and you get to pay for it (the evidence is that such systems don’t significantly increase the selling price for your house).

    It may seem like other things, but essentially that’s the “debate” when it comes to installing this technology in NZ. And that’s why there’s essentially no debate in some of the other countries that people have listed.

    That, and most people don’t like paying a big chunk of money up front.

    Maybe green energy isn’t a reality after you have looked at the whole picture – a bit like the bio-energy fiasco.

    I can answer that for you. I have looked at the whole picture in NZ (it was my job for a while), and green electricity is a trivially easy “reality” in this country. Green transport energy is much more difficult in NZ, but huge reductions in dirty energy are also possible there.

    Dunsandel • Since Nov 2006 • 1156 posts Report Reply

  • Andrew C, in reply to Moz,

    Technically NZ should already be at 90% renewable, as we were in the 1980’s. But politically? That’s just not an option

    I don't think you can blame it entirely on the politicians. Take a look at "Project Lachie", an attempt to extend some existing hydro capabilities. That was basically killed by environmental NIMBY complaints.

    Auckland • Since May 2008 • 168 posts Report Reply

  • Andrew C, in reply to Moz,

    In Australia Beyond Zero Emissions did a major study showing that a transition to 100% sustainable electricity by 2050 would be profitable even with unfavourable assumptions

    What exactly do you mean by this? To be profitable, what happened to the price in this study?

    Auckland • Since May 2008 • 168 posts Report Reply

  • Kumara Republic, in reply to Andrew C,

    That was basically killed by environmental NIMBY complaints.

    Out of curiosity, what proportion of them are actual environmentalists, as opposed to people acting out of property value self-interest? It's definitely a biggie with wind farms, as was shown in the docudrama The Age of Stupid.

    The southernmost capital … • Since Nov 2006 • 5423 posts Report Reply

  • Lucy Telfar Barnard, in reply to James Green,

    drain water heat recovery...

    A minor quibble, but presumably you'd need to adjust your shower mixer a bit in the early minutes of your shower, as the cold water starts to heat up and so the hot water needed becomes less?

    Wellington • Since Nov 2006 • 580 posts Report Reply

  • David Haywood,

    Russell, sorry not to have replied earlier but have had bad cold followed by possible "mild" influenza -- also looking after children with same.

    I'm going to be annoying by saying that you should definitely install solar water heating -- in about the year 2000. Given the problems with time travel then your biggest question should now be: will I still be in the same house in 10-15 years?

    The price sounds no worse than the standard rip-off as long as it includes everything -- HWC, plumbing, building permit, etc. You should double-check that there are no extras hidden away anywhere. As someone else has pointed out, the Chinese systems land in Auckland for about a grand, but there is nothing you can do about all the other fingers that manage to get in the pie on the way to your house.

    In general, the "heat pipe"* systems have a bunch of advantages over the flat plate absorbers -- in other words, the glass tube jobs are better.

    An important exception to this is the Thermocell panels, which look like a flat plate absorber, but are actually are a flat "heat pipe" system. These panels are easily the most elegant design available anywhere from an engineering perspective, and I know of 30 year old systems that are still going strong without any maintenance ever. The downside is that they're expensive.

    If you flip me the specs, I'd be happy to have a look at the proposed system for your house.

    In general, the inverter required to drive your HWC from a PV array would be pretty chunky -- don't want to go into a lot of detail but I'm not a huge fan of heat-pumps for HWC though I have designed/built them myself. I'm currently recommending that grid-connected PV should be only what you use as a "base load" during the day -- sounds like under a kW from what you say. This will change in the future.

    I guess I also have philosophical objections to the conversion of 100 per cent exergy from your PVs into 100 per cent anergy in your HWC. It's contrary to everything I do.

    My guess is that the biggest change in NZ will probably come when 2nd-hand batteries from electric cars start to enter the market. That will enable a very cheap battery to be integrated into your house/business and will change everything.

    I hate to answer money questions about the future, but I had the same debate (solar HW now -- or wait for cheap PV) with myself about 18 months ago. I installed solar HW. I guess that's sort of an answer.

    [* Not strictly a heat-pipe, I know, I know, because no wick.]

    Dunsandel • Since Nov 2006 • 1156 posts Report Reply

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