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SOLAR - WIND - giving back to the grid

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  1. #1
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    Default SOLAR - WIND - giving back to the grid

    For anyone in the know, what's involved with setting up a renewable electricity source and giving back to the power grid? I can get my hands on 300W 24V wind turbine generators. Is this suitable for giving back to the grid to reduce by lecky bills? How do I go about getting this installed and set up and is 300W 24V appropriate? Or do I have to use solar panels only? Can I use both? Anyone with any information, please let us know. I'd like to learn more about this topic.
    Other questions I have is, do I need batteries and an invertor or is that only if I'm going to use my generate power myself. Also, how much work will a sparky do on an installation like this before an expert in solar panels/wind turbines, needs to be called in?

  2. #2
    2K Club Member chrisp's Avatar
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    Tricky,

    Have a talk to Selectronic (a Melbourne based inverter manufacturer) or have a look at their web site. Also have a search for SMA Sunny Boy and SMA Windy Boy (coming soon..). You'll be able to get an idea of what's involved.

    The SMA inverters require considerably more than 24Vdc, but Selectronic has a new series of inverters coming out that'll work on 24Vdc and are approved for grid-connection.

    From my understanding, it probably won't be worth your while bothering with grid-feed for a 300W turbine (which may only produce about 100W on average).

  3. #3
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    Thanks for the tip on this site. Will have a look. As for the turbine, it produces an average of 300W and 500W max.

  4. #4
    2K Club Member chrisp's Avatar
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    Tricky,

    If I were you, I'd look into using the 24Vdc in other ways. Say, use it to charge a 24V battery bank and run a cheap (non grid-connect) inverter from the battery bank. You could then use the inverter for, say, recharging your cordless power tools. Or, even better, do you have anything that you can run directly from 24Vdc (outdoor lights)?

    You'll find there is quite a price leap between non-grid-connect ($100s) and grid-connect inverters ($1000s) which I think would make the idea of grid feeding 300W very uneconomical.

  5. #5
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    So what kind of wattage should I be pumping into the grid to make it economical? What's the norm?

  6. #6
    2K Club Member chrisp's Avatar
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    You can do a quick calculation:

    Most domestic consumers pay about $0.14 per kWh (kilowatt hour) for electricity. 300W is 0.3kW so every hour you'd save 0.3 x $0.14 = $0.042 per hour (or about $1.00 per day).

    You're ahead with the turbine (free) but you'd still need an inverter and I guess a small grid-connected inverter will set you back about $2000 plus installation.

    There is talk that the feed-back tariff will be something like about 4 times the buy-in tariff (i.e. you could get about $0.60 per kWh surplus fed back in to the grid).

    I think for most consumers the decision to install solar panels and an inverter isn't one based upon strict economics but rather one based upon doing the right thing by the environment.

    I'd certainly encourage you use the wind turbine and make use of the free energy, but I suspect there are more economical ways of using the energy directly rather than grid-feeding.

  7. #7
    Golden Member GraemeCook's Avatar
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    Hi Tricky

    There are many issues associated with wind/solar power and grid connection.

    First you must buy an expensive approved inverter (cheaper square wave inverters are not acceptable) and a reverse flow electricity meter, often called a smart meter. Some electricity suppliers will buy back the power at a price set by them (ie low), others will accept the power as a gift.

    Then there are planning issues - what is your councils attitude - and many/most wind generators are quite noisy - they may drive you/your neighbours batty.

    Now the good news. There are lots of government subsidies available - federal, state & local. The federal subsidies are detailed at www.orer.gov.au .

    Once you do you research on wind/solar you then I really think need to get an expert to look at your specific situation - your power usage pattern, and monthly wind and insolation patterns - and then design and size a system accordingly. Even with the subsidies, most alternative energy systems are installed because we think that they are good for the planet and our grandchildren's future, not for short term financial reasons.

    I think you will find the researching interesting

    Cheers

    Graeme

    PS: Because of economies of scale, especially the cost of approved inverter, smart meter and installation costs, you will find the the minimum economic size is at least ten times the capacity of your existing wind generator.

  8. #8
    Duck Fat - 2K club member SilentButDeadly's Avatar
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    Feeding back into the grid in Victoria is, to put it bluntly, a WOFTAM.

    For starters, the feed-in tariff is, whilst appearing generous, based on gross metering. In other words you are paid only for what is excess over the billing period (what you generated over that time less what you used over the same time). No big deal you might think. Except that you are not eligible for feed-in unless your solar system is less than 2kW - which isn't big enough to generate sufficient power to exceed average electricity use in your average 2.5 kid home. So the chances of making any dollars are virtually nil - but of course, you will get money off your bill.

    ...and I think wind power is totally excluded from feed-in.

    Next, your meter. Almost certainly not suitable so it has to be replaced. But even the new ones don't help much in terms of energy management.

    Ultimately, the solution is pretty much as Crisp suggested. Use the power you generate to disconnect certain circuits (like lighting) from the grid - disconnect more as your system size & capability improves.

    The ultimate way to go at the moment is solar or wind power feeding a battery bank to supply the house with support from mains backup. Pretty much the same as a remote power system but instead of the generator as a backup......you use the mains. Yes it is more expensive to setup because you need an inverter/charger (which manages the battery bank, inverts from DC to 240V AC and controls the interaction with the grid) AND a battery bank rather than just a simple grid connect inverter. Grid interaction remains possible especially with some inverter models so feed-in when you aren't exploiting excess power can be done - and because you aren't using so much grid power in the first place.....you might even have a sniff of a chance with the feed-in tariffs.
    People don't ever seem to realise that doing what's right is no guarantee against misfortune

  9. #9
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    i have recently had a system installed on my house, a 1Kw solar system. cost me $3000 dollars after rebates. total system is worth around $13000 now. as our house has gas oven gas heating and gas hot water our power use is around 6.5kw a day.. our system on average is producing about 6kw a day now and about 3 in the winter.. we will never make money but should save us having a huge bill.. thing to remember is when there is a black out you wont have power as the system stops for safety reasons.. if you are serious shop around some companies will install the smart meter as part of the deal as was mine, otherwise you are looking at around $400 to $500. next thing is that not all power suppliers offer buy back.. here in S.A. the buy back is about $0.40 per Kw i think???
    lots of things to consider as mentioned

  10. #10
    Golden Member GraemeCook's Avatar
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    Quote Originally Posted by sdrob View Post
    i have recently had a system installed on my house, a 1Kw solar system. cost me $3000 dollars after rebates. total system is worth around $13000 now. as our house has gas oven gas heating and gas hot water our power use is around 6.5kw a day.. our system on average is producing about 6kw a day now and about 3 in the winter.. we will never make money but should save us having a huge bill.. thing to remember is when there is a black out you wont have power as the system stops for safety reasons.. if you are serious shop around some companies will install the smart meter as part of the deal as was mine, otherwise you are looking at around $400 to $500. next thing is that not all power suppliers offer buy back.. here in S.A. the buy back is about $0.40 per Kw i think???
    lots of things to consider as mentioned
    Thanks sdrob.

    In southern Victoria and Tasmania a well designed one kilowatt photovoltaic system averages about 5 kilowatt hours of electricity per day, but they produce four to five times more power in January than July. (longer days, more sun) In Alice Springs they produce about 50% more and most of the rest of Australia is between those figures.

    In SA you are probably averaging around 6 kwhr per day over the entire year; or 2,190 kwhr per year. If your power cost is $0.10 per kwhr then you are saving $219 per year or a return on your net $3,000 investment of 7.3%. If you can sell some of the power back to the grid at a higher price then your return will be even better.

    This is a great return to you in cold hard cash, and a great return to our planet. Well done.

    Cheers

    Graeme

  11. #11
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    Anyone have any comments on who to deal with for buying a 1kW grid connected system? Or any comments on brands of equipment etc?

    I'm aware of one well known big company that's selling a system for just under $4000 installed after the rebates. Anyone have any experience buying one of these systems?

    Whilst I'm an electrician, I'm not an accredited solar designer or whatever it is you have to be to qualify for the rebates. So it seems easier to just buy a complete system "off the shelf" and let them do everything.

    Also does anyone know the details of the current rebate scheme whcih ends on 30th June 2009? Do I have to have the system up and running by then? Or do I just have to apply for the rebate (which is done before the system is installed) by then?

  12. #12
    Member Bullfright's Avatar
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    When I eventually get to Oz I intend to set up a wind/solar supply to run my 120 V tools and a few small load households plug ins. I have bought a small wind turbine and I have several inverters one of which is pure sign wave. I have used inverters for years whilst running tools off a car battery and have never had a problem. I also have a portable caddy with a car battery and an aluminum post with two compact flourescent lamps on the top for the many times when the trees bring down the power lines here. I can sit and read or watch TV for hours.
    This will be my major passtime when I settle but if and when I want to tie into the grid, I think I will let the experts do it and collect the grants.
    This is a great thread! I hope it keeps going........

  13. #13
    Old Chippy - 4K Club Member
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    Some good points in above posts but careful not to blurr solar photovoltaic systems with the wind generator in the initial question. As a number have said residential scale wind generators are not even close to being worth it even in the ACT where the new feed-in rate from 1 March will be 3.88 times the current retail - so around 50c kwhr. The ACT scheme is the most generous in the country, but has some traps for unwary players so anyone going into solar needs to research very thoroughly. But on a 1kW PV the ROI will be around 8-10 years so much better than before (around 18-25 years more for a larger system).

    A big catch for anyone installing any solar item - including solar HWS is that if you turn over your Renewable Energy Certificates (RECs) to the supplier (they have a cash value that is usually offered in the same way as a trade-in or discount) then you home system will do nothing much to reduce greenhouse gas emissions - the RECs will be bought by a polluter to allow them to keep polluting. Sure the generation you make using the sun reduces the emission over time, but a large proportion of your system is simply allowing others to emit.

    The way to prevent that is to hang onto the RECs, but that adds to the price of your system too.

  14. #14
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    Good point about the RECs Bloss - I was looking at a Solar hot water system myself and I guess I am just giving some big coal power station licence to keep poluting.

    Still, hopefully I will be reducing my instantaneous/ongoing power use so that surely must prevent some CO2 emissions?? (well I guess it probably won't because more people are still moving here and population is generally growing so there's no less power being produced.....)

  15. #15
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    Quote Originally Posted by Bloss View Post
    A big catch for anyone installing any solar item - including solar HWS is that if you turn over your Renewable Energy Certificates (RECs) to the supplier (they have a cash value that is usually offered in the same way as a trade-in or discount) then you home system will do nothing much to reduce greenhouse gas emissions - the RECs will be bought by a polluter to allow them to keep polluting. Sure the generation you make using the sun reduces the emission over time, but a large proportion of your system is simply allowing others to emit.
    Add in the Carbon Pollution Reduction Scheme (CPRS) and bottom line is you can't alter national CO2 emissions no matter what you do.

    My own interest in PV is, believe it or not, largely driven by financial considerations. Basically it's an inflation hedge - lock in a portion of future energy consumption at a known, fixed price that the government just happens to be offering to pay most of (until June 30).

  16. #16
    Old Chippy - 4K Club Member
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    Quote Originally Posted by Smurf View Post
    My own interest in PV is, believe it or not, largely driven by financial considerations. Basically it's an inflation hedge - lock in a portion of future energy consumption at a known, fixed price that the government just happens to be offering to pay most of (until June 30).
    Likewise - I have used some 10, 15 and 20 year calculators based on varying energy prices and I reckon it is a good investment. Most suppliers uses the current cost of power and gas - even small increases (using Net Present Value - NPV) of 15% make the numbers much better - and I reckon we will see doubling (200%). But of course ya have ta have the cash . . . I don't think I'd be borrowing to do it just yet (although I reckon that's not far off as a level of certainty).

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