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Thread: Solar Panels - Water Heating During the Day

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    Default Solar Panels - Water Heating During the Day

    For some reason,yet to be determined, we are using about 30kWh more per month over the last two months than I would expect. That is just an aside for the moment.

    When the solar panels were installed so was a smart meter. The existing meter remained, I assume, to switch the hot water heating on/off at the appropriate time of the night.

    The grey cells kicked into gear thinking about the recent electricity bills.

    Given that the FIT is only 7.5c/kWh I was wondering is it possible to have the solar panels heat the water during the day?

    Is it as simple as disconnecting the existing meter and using a new timer to switch the hot water on from say 12:00 - 14:00 hrs?

    If it is possible there are a few issues:
    1. If the day was cloudy then I would be paying full rate from the supplier for the shortfall from the panels.
    2. Ring the supplier and say that I do not want controlled load anymore so the daily supply charge no longer applies?
    3.I would be looking for a payback period of about 1 year therefore an all up cost for parts and labour around $200.
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    Do a goggle search for "solar hot water diverter"

    I'm surprised your solar installer didn't try to sell you one with the system (they should really be standard equipment if you have an electric HWH).

    Your dual-meter thing sounds a bit weird, usually they just replace your old meter with the new one.

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    I was offered something at the time of the install. Given the sound of the device (EDIT: The way it worked.) and the cost, about $650 from memory, I decided it wasn't worth the money.

    I agree about the new smart meter. Why the old one was left I can only surmise that it was to turn the water heater on/off - although I would have thought that a "smart" meter could do that.

    EDIT: Did a quick search and OMG the prices. I can buy a hell of a lot of off-peak hot water heating for that, plus, one is still paying the daily service charge!!!!!!!!!!

    Where these glowing reviews come from is anyone's guess.
    Last edited by Guiseppe; 16-05-21 at 01:36 PM.
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    "What has changed between the arrival of the First Fleet and today?"
    "Wearing leg irons is now not required."

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    With rebates etc. you might be better off puting that money toward converting to a solar hot water system?

    You can use your existing EWH as a storage tank so all you have on the roof is a flat panel, you just have to add a heat pump (which also runs off electricity). Plus you can still use electricity to boost your hot water needs if we ever have a nuclear/volcanic/meteoric winter!

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    when i had my system installed i had a timer fitted for the hot water heater
    and is set to turn on at 12.00 and off at 3pm.

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    Storage hot water systems are lossy ; we moved to instantaneous LPG hot water years ago =)

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    Quote Originally Posted by wotnot View Post
    Storage hot water systems are lossy ; we moved to instantaneous LPG hot water years ago =)
    As did we. now all I need remember is to fill the gas tank from time to time. Last time was over 12 mths ago!
    I'm out of my mind, but feel free to leave a message...

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    we fitted a 3kw solar system to this house about 5 years ago , and its paid for itself. Average of 300 sunny days per year on the Capricorn Coast. We were offered the time clock initially but then the installer decided a 3kw system would have been to small for the task and a 6kw would have been better. mind you there are only 2 of us living here and everything is LED and low consumption.

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    Quote Originally Posted by fandtm666 View Post
    when i had my system installed i had a timer fitted for the hot water heater
    and is set to turn on at 12.00 and off at 3pm.
    How well does it work?

    I assume it is fitted in the meter box? The reason I ask that is because we have the inverter next to the switchboard in the laundry. I would be ashamed if the installation was in a cowshed. I told the installer, in as many words, that it looked 'kin awful - he said it was regulations.

    Further details please.

    To Bigfella237, wotnot and lsemmens. We are all electric and do not want significant outlay on new installations.
    Last edited by Guiseppe; 17-05-21 at 12:09 PM.
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    Quote Originally Posted by Guiseppe View Post
    How well does it work?

    I assume it is fitted in the meter box? The reason I ask that is because we have the inverter next to the switchboard in the laundry. I would be ashamed if the installation was in a cowshed. I told the installer, in as many words, that it looked 'kin awful - he said it was regulations.

    Further details please.
    Works great , yep the timer is fitted in the meter box and
    i can adjust it during winter and summer to work better.

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    Approximate cost?

    What did you do about the daily supply charge?
    Last edited by Guiseppe; 17-05-21 at 12:14 PM.
    If Australia is a democracy why, then, is voting compulsory?

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    "Wearing leg irons is now not required."

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    timer setup cost me couple hundred installed
    and i could set the total time on and hours etc
    once i had a good graph showing peak production
    from my panels.

    """""What did you do about the daily supply charge?""""

    not sure what you mean there mate my production covers
    what is use to heat the tank because i have a 9.8KW system

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    Quote Originally Posted by fandtm666 View Post

    """""What did you do about the daily supply charge?""""

    not sure what you mean
    The electricity supply company charges us a daily supply charge for normal electricity and a separate daily supply charge for "Controlled Load" i.e. hot water heating.

    Your timer sounds exactly what I am looking for. The sparky supplied it or ...?
    Last edited by Guiseppe; 17-05-21 at 04:46 PM.
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    Quote Originally Posted by Guiseppe View Post
    For some reason,yet to be determined, we are using about 30kWh more per month over the last two months than I would expect. That is just an aside for the moment.
    I have come to the conclusion that it is Director, Finance and Planning's electric blanket!
    If Australia is a democracy why, then, is voting compulsory?

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    Quote Originally Posted by Guiseppe View Post
    The electricity supply company charges us a daily supply charge for normal electricity and a separate daily supply charge for "Controlled Load" ~
    I would say that's because you have two separate meters, seems like they're charging you as if you have two separate supplies?

    I reckon if it was all one one meter then they could only charge you once. I'd be making some phone calls about getting that fixed.

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    It is standard procedure with Essential Energy - well for the last 20 years or so that I can remember and a number of different residences.
    If Australia is a democracy why, then, is voting compulsory?

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    if you have solar and a smart meter then i would lay odds the
    second meter is doing jack shit apart from taking space.

    If you are being billed control load then that would be part
    of the deal you signed upto.

    The smart meter handles it all - peak - of peak - shoulder etc.

    and you mentioned only getting 7.1 cents FIT then id be changing providers
    im with origin and getting 17.5
    Last edited by fandtm666; 17-05-21 at 05:16 PM.

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    Quote Originally Posted by fandtm666 View Post
    if you have solar and a smart meter then i would lay odds the
    second meter is doing jack shit apart from taking space.

    If you are being billed control load then that would be part
    of the deal you signed upto.

    The smart meter handles it all - peak - of peak - shoulder etc.

    and you mentioned only getting 7.1 cents FIT then id be changing providers
    im with origin and getting 17.5
    Why didn't "they" remove it then? I don't give a damn though.

    It is part of Essential Energy. Got an EWH then straight onto a Controlled Load Plan.

    I have a spreadsheet with last years consumption and ran the rates with a number of providers and I am waaaaaaay ahead of Origin/Essential Energy overall.

    It should be noted that I was with Origin, seems like forever, until last year when they decided to play silly buggers and jacked the electricity rates/dropped the FIT rate. I changed supplier and after everything was signed I received a phone call from a guy at Origin who promised me the world, almost literally. I told him that I hoped the phone call was being recorded and that if I had been offered the deal a month previous then Origin would still have a customer.

    EDIT: I think their rates may have been amended since then - maybe I wasn't the only one to jump ship.
    Last edited by Guiseppe; 17-05-21 at 05:43 PM.
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    I don't normally inhabit this part of Austech and I was searching for something else but I thought it might be worth chucking in 2 cents worth of hot water.
    Which is actually a lot more than my hot water bill for the last 2 years.

    I moved completely off grid. Grizzly Adams style so I have had to build everything myself from scratch and usually from junk.
    I scrounge solar hot water tubes when I can, which I put on my other house and only every had to turn the electricity on to the tank in winter when there was more than three days of cloud cover. I just picked up a surplus array for $50 and I'll plumb it into whatever I can later.

    Living off grid you can live ok without electricity, it's not fun but you can do it comfortably. Living on 12V is a bit of comfort and 240VAC off grid is comfortable.with 5KVA/20KWhr.
    But there is one thing that makes the difference between surviving and cushy living and that is HOT WATER. My sanity is recharged with a hot shower. It can be -5 degrees and if that shower is 60deg, I'm good.

    When I first set up, it was summer and cold showers were ok. But as winter came, that shit got old real fast so I scrounged some of the old solar heart flat panels and plumbed it all together. I scrounged an old hot water tank for $20 to store the water. I set it up as a thermo-syphon so it doesn't use any electricity.

    So my entire cold/hot water system consists of a cold water rain tank elevated as high as possible to give as much pressure as possible. (but I still use a 12VDC pump for good pressure) The hot water tank sits on the ground below it. Cold water flows into the bottom of the tank and the hot water is piped out the top as you would expect.
    The solar hot water panels sit below the hot water tank and are plumbed into the bottom of the tank so that cold water flows into the panels via a T piece from the cold water tank to the bottom of the panels and then out of the top hot water flows uphill back into the tank.
    That setup alone provide me with more hot water than I can use for about 300 days of the year. Free hot water.

    So the trick is what to do with the other 65. Well even most of those days provide water warm enough for a shower. But as it gets colder you struggle to maintain comfort.
    On grid,I would just turn on the 240VAC for a day and turn it off and it would last me about 3 days. But off grid, I had get creative. More thermal panels just doesn't cut.

    So I wired up the heater element in the old tank. It still worked ok. But running my 240VAC off grid solar into it would bleed me dry in hours.
    So I deciede just to go brute force DC solar on the element. Now everybody I spoke to said "ya can't use DC on hot water systems".
    To me that was just bullshit and when I asked why not, nobody gave me a sensible answer. So I wired up my tank to 240VDC straight from an array of old $5 panels I'd bought from the scrap yard. 1KW of crappy panels for $50. It works 100%. It's 7deg outside right now and I just had a nice shower. Sweeeeet.

    So, the reason why you can't normally use DC on solar hot water systems is the thermostat. Each time the thermostat opens the circuit because the water is hot enough it will draw a bloody good arc and quickly burn out the contacts or set itself on fire. The simple solution is just wire the thermostat out of the circuit and run the solar electric panels closed circuit to the heater element. This works a charm. At night the panels don't heat the water and even during cloudy days they crank it up.

    This does present a small element of danger, because there is no thermal regulation the panels will just keep heating the tank (until the relief valve blows or it explodes).
    But if you're managing it yourself, then there is no worry of this happening. The simple rule is you keep the solar electric panels turned off until you turn your shower hot water on and not the cold water tap. If the water becomes too cool, turn the panels on. When the water is hot enough that you have to turn on the cold water more than a small amount, turn the panels off (but do it at night -during it under load during the day will burnout the breaker or switch unless you design a high load DC break with arc snubbing.
    But it's fun drawing an arc with something like a knife switch.

    I could automate the process, but I like to manage it manually. The only other thing is that the idle panels tend to corrode during summer when they have a kick arse charge and nowhere to dump the power. Give them something to do like a 240V light globe or a water feature pump and they're be happy.

    So you might think, that's all very nice given I can just build this shit in a paddock, but it's not real practical on a house. Well, actually it is.
    As mentioned, if you have solar hot water and on grid, just flick the switch. If it is off peak power, it's cheap. But if you have roof space, you can put surplus solar thermal on yourself.
    It's not hard to do but it's not everybody's thang. You can of course just put solar panels on as a DC system. 1kW of panels will do it and piss easy to install yourself.
    (ok, I might be ignoring some rules, but fvck it, I can make it safe.) Then you can manage it manually like I do, but you'd be tuning it on and off a lot during summer.
    If you're smart enough to build your own DC break system and temperature control, then that's also easy.

    A dual element tank lets you keep on grid electricity and you can wire in solar to the other element.
    If you have the space, then just buy a cheap second tank and set it down beside you good tank. Pump in your tank into the spare ports of the good one or use T pieces and some ball valves and let the mains water pressure push the water through your off grid solar tank. Then if you have a issues, you can switch between the tanks or run both.

    I'm getting to the point now where I have so many spare solar thermal water panels (I get them for free most of the time) I'm going to start using all surplus energy for thermal heating. The hose will cost me more than anything else.
    Yes I am an agent of Satan, but my duties are largely ceremonial.

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