Taking the power back– Green Party Solar Homes policy

The path to something great often starts with something simple. In the case of solar, it’s two basic questions -–do I have a roof? Does it get decent sun?

If you answered yes to both, you’re already on your way to cheaper, cleaner power.

And that is what the Greens want for all New Zealanders, and what our new Solar Homes policy is about.

Solar Homes infographic

Launched yesterday to much acclaim, Solar Homes offers low-cost Government loans to households so they can install solar PV on their roofs, tap into abundant green power and generate their own electricity. I repeat – low cost Government loans, which households pay back (the National Party has called the scheme a subsidy. It’s not). This is deeply ironic given National is bending over backwards for the oil industry with $45m in tax breaks this financial year and $25m in seismic survey subsidies paid by the taxpayer.

People’s monthly power bills are too high and climbing. Solar Homes is about breaking free from the big energy companies and taking the power back.

An average solar PV system will leave a household $100 better off a year (producing $1000 of electricity at current prices, but only costing $900 to pay off over 15 years). And after the loan’s paid back, the system will continue to produce free electricity for the lifetime of the panels

The initial installation costs about $10,000. Any excess power generated can be sold back to the grid.

The loans will be repaid through rates and attach to the house, so people can invest without the concern they’ll lose that investment if they move house.

Solar makes sense – in fact some of the stories are remarkable. The Hughes family in Nelson put in solar PV last year and recently received a monthly power bill of $1.80. That’s cheaper than a litre of milk.

Many New Zealand homes are exposed annually to 20-30 times more energy from the sun than they actually use in electricity or gas. Most of this is going to waste. By harnessing it instead we can reduce emissions, create local green jobs and achieve energy independence. And all from the starting point of a sunny roof….


To watch Green Party co-leader Russel Normal launching the policy yesterday, go to: http://new.livestream.com/nzgreens/events/2766975

To read more about the policy go to: greens.org.nz/solarhomes


32 Comments Posted

  1. Roman, that you think that a mere 0.6 watts/sqm (by your calulations) is of no significance is irrelevant. What did the earth do last time GHG concentrations changed this much?

  2. Heres the calcs;
    1 ton of TNT = 4.184e+9 joules (J) source
    Hiroshima bomb = 15 kilotons of TNT = 6.28e+13 joules (ibid)

    Hansen says increase in forcing is “400,000 Hiroshima atomic bombs per day”, which comes to 2.51e+19 joules/day.

    A watt is a joule per second, so that works out to a constant additional global forcing of 2.91e+14 watts.

    you look at forcings in watts per square metre (W/m2). Total forcing (solar plus longwave) averaged around the globe 24/7 is about 500 watts per square metre.

    To convert Hansen’s figures to a per-square-metre value, the global surface area is 5.11e+14 square metres … which means that Hansens dreaded 400,000 Hiroshima bombs per day works out to 0.6 watts per square metre … in other words, Hansen wants us to be very afraid because of a claimed imbalance of six tenths of a watt per square metre in a system where the downwelling radiation is half a kilowatt per square metre … we cannot even measure the radiation to that kind of accuracy.

    Nice try at scaremongering but the facts belie the claim. How long must we go on with the facts being omitted and incorrect claims being made.

  3. err BJ, you do realise that the Hiroshima “gadget” just opens the door for people to illustrate (1) the diminutive size of the radiative imbalance in relation to the amount of sunlight and infrared radiation that warms the planet every day, and (2) the massive uncertainties behind the imbalance.
    Its a massive own goal for SKS and shows they don’t really understand.
    You guys need to catch up. You seem to be clinging to old science.
    “the world will warm 5 degrees and the seas will rise 10 meters” blah, blah, blah.

  4. If the Greens could do just one thing in the next say 15 years, that one thing would be to improve New Zealand’s building standards, and thus, eventually the housing stock. Make buildings more energy efficient.

    In the long term, this one measure effects most things that the Greens are interested in, energy, sustainability, health, the list goes on…

  5. DBuckley, thanks for that link, and the subtle reminder that we aren’t building houses anything like this. That encapsulation seems useful but one has to ask why it hasn’t been marketed.


  6. Phase change materials have been used for managing heat, see NZi3.

    And Trevor29 is absolutely right about the limitations of batteries in solar PV installations. Essential if you’re off-grid, but on-grid, well, that’s what the grid is for.

  7. Trevor, I was thinking of hot water heaters and similar arrangements not the high temperature salts. There are lower temperature phase change materials that can store heat. People were working on this 20-30 years ago. I know that several working Solar houses managed it in different ways. Trick is to have a way to do it in a New Zealand not-quite-a-real-house.

  8. @BJ – Concentrated Solar Thermal Power which uses mirrors to focus the sun’s light onto a thermal collector and achieves very high temperatures only works with direct sunlight. Sunlight that has been scattered by clouds doesn’t focus properly. It is a very promising technology in the right places, but the land of the long white cloud is not the best place.


  9. The problem with using batteries for electricity storage is the high cost and limited life of those batteries. For some battery technologies, 1000 charge-discharge cycles is about the limit – around 3 years of daily use assuming one charge-discharge cycle per day and not fully discharging each time. The cost of replacing the batteries every 3 years can be several times the cost of the electricity stored!

    Storing the electricity in utility-scaled systems such as pumped hydro storage usually works out much cheaper than batteries. The only advantage I can see from having batteries at the same site as the solar panels is the ability to size the inverters to around the average output of the solar panels rather than the peak output. Of course if you have a need for uninterruptable power and need the batteries anyway, it is a different story.


  10. There is a difference in the way the Sun hits Wellington and the way it hits Auckland, particularly in winter. Vector may well get a good play out of Sun Genie but I don’t think I would here in Welly.


  11. Could Solar Thermal and Storage schemes which store HEAT be eligible. The phase-change salts or chemistry and storage space could be a problem in the cramped quarters we are building for ourselves, but that storage is I think, apt to be more efficient than most electrical installations… and no, I do not have any tech in mind, nor have I noticed anyone building anything useful here. It is simply an idea.

  12. Solar is viable. Vector runs a solar installation scheme currently. To quote their site: “As a network operator, we see a lot of benefits in homes being able to make and store part of the electricity they use. One of our big challenges is balancing load across the network at peak times. Homes that have solar electricity stored in batteries reduce the load on the grid, which is good for everyone.”
    Is there any reason people couldn’t include battery storage in their chosen system?
    Contrary to claims that solar is no good for urban settings or NZ conditions Vector seems to think it is: “”As a rough guide, under standard conditions, a SunGenie 3 can make up to 16kWh a day in peak summer conditions, and up to 7kWh a day in midwinter for an annual average of up to 12kWh a day. The average Auckland home can supply up to 50% of their own power needs with a SunGenie 3.”

    From time to time we may seek to charge, or draw power from, SunGenie’s batteries to help run our network more efficiently and deal with interruptions to supply (such as during or after an outage). We can explain in more detail how and when Vector might carry out such actions when we go through the contract with you. If you’ve arranged a power buyback deal with your retailer then you’ll always be paid for any electricity that is exported from your property.

  13. The way to reduce those heating needs is to have better buildings. We know how to do this stuff. The problem is that there are two problems considered in isolation, energy use and energy production. The reality is that by addressing the energy use side of the equation, the energy production needs can be reduced.

    When BJ says, above, “it is important to include the costs of BAU, never acknowledged by economists in their analyses” he’s absolutely right. Though he’s in the wrong context, he’s describing a ticket-clipping tariff as a cost, but when comparing energy production and use there are real costs on both sides of the equals sign, and one can adjust things to make matters better overall.

  14. The areas that are summer peaking have high dairy irrigation loads, whereas the areas that are winter peaking have high urban loads, which is where this policy will be installing the solar panels.

    As we try to move away from fossil fuels, we need to find alternative ways of heating those buildings currently using gas, oil or coal. We also have water heating to address. Our winter peaks will be with us for some time.


  15. Just noting that in the area I live, North Canterbury, which has Mainpower as its line company, a number of zones are now summer peaking. Source: Mainpower Asset Management Plan (PDF, 6MB) table 14.

    Solar wont contribute in any way to evening loads, but can make a dent on the daytime commercial load, which for many businesses is often just working hours.

  16. Gareth – on what basis do you make your claim that investing in solar panels will reduce New Zealand’s electricity system’s infrastructure costs?

    Unlike South Australia, our peak electricity demands are in winter evenings, when the output of solar panels is zero. The main infrastructure costs are incurred in trying to meet peak demand, and dealing with the winter period of high demands during bad weather – the very times solar panels don’t generate anything significant.

    There are a lot of countries and areas where the peak electricity demands are caused by air conditioning loads during hot afternoons and for these countries solar power can reduce the peaks and shift the remaining demand until later in the day, but New Zealand is not there yet and won’t be for some time.



  17. PAB – you need to provide a bit more information to justify and context your claim of a 10 year energy return break-even point. The same solar panel can generate twice as much energy in Australia as it can in Germany. Does it include an aluminium mounting frame, which can probably be reused after the panel dies, and which can be recycled at a much lower energy cost than starting from new? Similarly with the copper wires. I would expect that eventually the solar panels themselves could be recycled. Different panels have different costs and different outputs, all giving different energy return break-even times. Is your 10 year figure 10 years out of date?


  18. dbuckley and trevor29.

    Don’t worry about the pricing, under a Labour/Greens government the state will buy ALL electricity at a fair price. NZPower it is called.

    Price will be a the behest of the state.

    Surprised the Greens have not mentioned the state monopoly on electricity purchasing (seeing it was their baby) in this solar power initiative.

    Investing into a $15K solar power system where the resale price of electricity, generated by individually owned solar power stations, is set by the whim of the state. Not sure if that is going to make a lot of people invest no matter how good the “green” benefits.

  19. PAB – The cost of the panels is usually not more than about 20-25% of the installation costs. Once installed they can be replaced far more cheaply, so there are some missing numbers in your simple analysis.

    The other missing number, missing too in the energy industry analysis of course, is the cost of damage from the burning of coal. That is never counted when the cost of Solar or Wind is described as “uneconomic”. Given that cost of $150/tonne or so, though at some levels it could be much higher, the same analysis will find rather different cost benefit.

    Which isn’t the same as saying this is the best way to do this, but it is important to include the costs of BAU, never acknowledged by economists in their analyses.

  20. @dbuckley – actually there is a justification for the electricity retailers to pay above the spot price. The spot prices are at the Transpower Grid Exit points, whereas the home solar power is injected into the local network. Providing this is less than the local demand, power flows from the Grid Exit points to the local distribution network and the losses in this power flow are lessened by the local generation. This makes the local generation worth more than the spot price. However the difference is not large.


  21. The maths for this scheme is all shonky.
    They won’t produce $1k power pa. There is the implicit assumption there that the retailer will pay the same for your power in the middle of the day as what it costs you to buy it from them. Around 1pm at maximum generation, most households have little consumption so it has to be exported or dumped. Why should they buy power at 20c/unit when they can get it, and a lot more reliable supply from the centralised generators for a third of that price. As dbuckley points out, it relies on others to pay for the network – another hidden subsidy.

    One of the many problems with this scheme is the solar panels aren’t reliable. Industry experience is about 30% failure rate. The inverters also seem to have a life of about 5 years. Factor those into the economics and this is another loss maker.

    Solar cells and/ or wind are very good for remote sites. They are not on places connected to the grid.

  22. Any excess power generated can be sold back to the grid.

    This is the big, hairy unknown in this policy. Just how much will solar owners be paid for their excess electricity. The policy is dodgy on this question.

    The only equitable and fair answer is “the spot price”, or perhaps just slightly unfair, some sort of average spot price during the solar hours for the month.

    Why is this fair? The electricity retailers pay the spot price for their electricity when generated from other sources, so there is no reason they should pay any more for it if it is generated by solar. If they were to pay more for solar than to others, then the net effect is their cost base would rise, and they would obviously (and righteously) pass that cost on to their customers. So you have the folks without panels subsidising the folks that do.

    Other than that, an interesting policy.

    Solar makes sense – in fact some of the stories are remarkable. The Hughes family in Nelson put in solar PV last year and recently received a monthly power bill of $1.80.

    Of course, these kind of notable, exceptional bills can only happen when the Hughes family are very much an exception. If every consumer in the country paid $1.80 a month to their utility, there would be no utilities, no utility infrastructure. The Hughes family can only pay $1.80 because we are all paying the costs of the infrastructure to support their connection.

  23. The energy footprint of solar panel maunfacture takes 10 years to offset with the electricity they generate. All chinese panels are made with energy from low grade coal. The climate change impact of the carbon emissions from solar panel manufacture and install negates any benefit from the solar power they generate. If true cost pricing of panels included the environmental harm of manufacture they would be accurately unecomonic to use.

  24. Surely the idea is about promoting clean alternatives to burning fossil fuels.. NOT just ‘penny pinching’ !!
    I think the REAL saving will be made on reducing the effects of climate change in an uncertain future.

    kia ora

  25. This looks like a good policy, it’s economically responsible and promotes a environmentally positive choice on an individual level. I’d like to see support for something similar for schools, perhaps like the schoolgen project. Schools use a lot of their energy during the day, so it makes sense to supplement with Solar.

  26. Great stuff, some real longterm solution both to the corporate attempt – aided by National – to clip the ticket on all necesities and to push our energy systems toward sustainable climate solutions. Keep up the good work as people are waking up and the economic cost of weather event insurance hit a record $174m and climbing last year. As only part of the cost, without even looking at long term ecological damage this scheme is low cost and sensible

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