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  1. #1
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    Default Avoiding solar power throwaway

    So, when the batteries get fully charged and the house runs off panels in the daytime, how do you utilise the extra solar power? Assuming that you cannot pump power back into the grid. Not buying extra batteries - too expensive.

    1) Geysers are set to heat up in the day. Even the solar geyser benefits from 220v pushing it a bit more.
    2) Thinking to do the same with the bathroom tiled floor underfloor heating from 11h00 - 16h00, but initial testing shows that the heat retention is not that great to last the night.
    3) With soup and stew season upon us, we are supplementing the gas hob with a cheapie induction stove plate for daytime use. So hopefully saving some LPG costs over time. Also seeing if we can cook other meals in the day, and just heat at night.
    4) Washing machine and dishwasher run in daytime only.
    5) I guess one could make ice in the day in the camping fridge, and pop it in the top of the fridge at night, but that seems hardly worth the trouble. Especially in winter.

    So without buying any extra batteries or investing in a cryptomining rig any thoughts on how else to utilise solar generated power that would just be lost? I guess my Dutch heritage is beginning to show.
    Make it happen!

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  3. #2
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    Default Re: Avoiding solar power throwaway

    Following with interest.

    The best I could come up with is making ice during the day. And now I have a lot!

    Edit to add: What I also do is to irrigate the garden during day, especially now that it is winter and less evaporation taking place, provided you have a similar setup as me which entails having a something horsepower water pump coupled to 2 x 5000L water tanks. So water is free and electricity is free.
    Last edited by Die SwartKat; 2021/05/12 at 02:03 PM. Reason: Edit to add
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  4. #3
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    Default Re: Avoiding solar power throwaway

    Get one of these outside your property for the neighbors to charge their devices
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  6. #4
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    Default Re: Avoiding solar power throwaway

    I am also curious about ideas, a friend and I have been discussing for a while as the cost of batteries are just too high to justify, so some other clever ideas would be good.

    Perhaps an arrangement with the neighbour to run his pool pump during the day in exchange for something else of value?


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  8. #5
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    Default Re: Avoiding solar power throwaway

    Heat the swimming pool and jacuzzi?
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  9. #6
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    Default Re: Avoiding solar power throwaway

    I would suggest that you add an additional normal electric geyser (+-R3000) from where you feed your solar geyser. When you have surplus electricity you send it to the geyser.

    So instead of battery storage you have warm water storage

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  11. #7
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    Default Re: Avoiding solar power throwaway

    I pump a portable aircon / heater when there is extra power to keep the house at a nice temp.
    I also use an instant pot for cooking during the day. Keeps it warm for dinner.
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  12. #8
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    Default Re: Avoiding solar power throwaway

    Quote Originally Posted by Toccata (Roelof) View Post
    So, when the batteries get fully charged and the house runs off panels in the daytime, how do you utilise the extra solar power? Assuming that you cannot pump power back into the grid. Not buying extra batteries - too expensive.

    1) Geysers are set to heat up in the day. Even the solar geyser benefits from 220v pushing it a bit more.
    2) Thinking to do the same with the bathroom tiled floor underfloor heating from 11h00 - 16h00, but initial testing shows that the heat retention is not that great to last the night.
    3) With soup and stew season upon us, we are supplementing the gas hob with a cheapie induction stove plate for daytime use. So hopefully saving some LPG costs over time. Also seeing if we can cook other meals in the day, and just heat at night.
    4) Washing machine and dishwasher run in daytime only.
    5) I guess one could make ice in the day in the camping fridge, and pop it in the top of the fridge at night, but that seems hardly worth the trouble. Especially in winter.

    So without buying any extra batteries or investing in a cryptomining rig any thoughts on how else to utilise solar generated power that would just be lost? I guess my Dutch heritage is beginning to show.
    I switch on my pool pump through when batteries are full.

  13. #9
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    Default Re: Avoiding solar power throwaway

    Lol I only charge Camera and Head Torch Batteries and the cell phone at home but Charge up the Trailers 2x 105's once a month when not travelling So I wouldnt know
    Last edited by Peter Betts; 2021/05/12 at 04:03 PM.

  14. #10
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    Default Re: Avoiding solar power throwaway

    Ok, so checking all the suggestions...

    - Our irrigation/water pump may be set too early, before sun is high enough. Will check on that, ta.
    - Only 6 neighbours and they would have very little interest in a charging kiosk or a cable over the wall (plus they run 3phase, I don't)
    - Don't have pool or jacuzzi myself; that would be a good idea though.
    - Geysers actually are electric geysers hooked up to a separate solar pump. The solar part does part of the heating, but I boost it through solar 220v to 66+ as well. Good place to store energy.
    - We use an oil heater for the study in the daytime. Heat retention elsewhere in the house is just not good enough to view as energy storage. But I need to experiment a bit more with this. In summer I'm definitely not shy to run the aircons.

    Thanks for all the ideas so far.
    Make it happen!

    2018 Mobi Lodge

  15. #11
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    Default Re: Avoiding solar power throwaway

    The morning sunlight fills the batteries, afternoon sun is for geysers, swimming pool, cooking ( electric oven/induction plate). Ironing, washing machine). In addition underfloor heating ( tiles tiled floor. Also run Airconditioning ( to heat or cool) in afternoon.

    17h00 all quiet again and batteries full for overnight duty.

  16. #12
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    Default Re: Avoiding solar power throwaway

    Water pumps chow kw quickly so I run borehole pump, booster pump & house pump on access supply and maybe pool pump in summer, all depends on your setup that may need to service different needs
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  17. #13
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    Default Re: Avoiding solar power throwaway

    Quote Originally Posted by Kamakazi View Post
    Water pumps chow kw quickly so I run borehole pump, booster pump & house pump on access supply and maybe pool pump in summer, all depends on your setup that may need to service different needs
    My irrigation water pump draws about 400 watts, so about 0.5 horsepower.
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  18. #14
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    Default Re: Avoiding solar power throwaway

    I had two 150l geysers one for each bathroom that happen to be not too far from each other.
    I then connected them in series with the main geyser feeding both bathrooms and the feeder just as input to main geyser
    I replaced the feeder geyser element with a 1kw element.
    I then also have a small 220v pump (was spare for geyserwise) that takes the main geyser output to the feeder geyser Input.

    Any extra solar is fed to the feeder geyser 1kw element Starting as early as 09:00 the morning
    If the feeder geyser temperature is 5 degrees or more than the main geyser I circulate the water for a period bringing the main geyser temp up.
    This way at 17:00 I normally have two geysers at more than 55deg, when taking a bath or shower the evening the main geyser remains on 55 degress and only the feeder drop temperature, thus by next morning the main geyser is still hot for a shower or bath and the cycle can start again.

    I have geyserwise backup that at 04:00 in morning or 16:00 in afternoon bring the main geyser temp back to 55 if not already at this temperature.

    I am contemplating of adding more solar and increasing the feeder geyser element to 2kw as rignt now there is still some mains power used early in the morning and some time late afternoon to top op the main geyser.

    See graph for today's trends:
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  19. #15
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    Default Re: Avoiding solar power throwaway

    Quote Originally Posted by Libdoo View Post
    I then connected them in series...

    Any extra solar is fed to the feeder geyser 1kw element
    I like this idea.

    How is the extra solar fed to the geyser? How does it work practically (only if surplus, turn element on)?

  20. #16
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    Default Re: Avoiding solar power throwaway

    It is difficult to know when you have surplus solar looking at the solar generations/Solar output , and decided to use the battery load and SOC rather to see if there is surplus, I run of solar and battery during the day and only fallback to mains if the battery SOC is below 40%

    i use a Sonoff(tasmota) with temp sensor and Solid state relay controlling the feeder/backup geyser, and another for the main geyser an circulation pump.
    Then using node red and some rules to read inverter info and Sonoff's temperature info to then manage the sonoff switches.

    it is then as good as the rules you can define

    My current rules , that have been working great for me are:

    if Current time > 08:30 and Current time < 17:00 then manage the geyser element
    if Utility is off and SOC < 80% then do not switch element on
    if Time is before 10:00 and SOC has not reached 60% then do not switch element on
    if time is after 1500 and SOC has dropped below 80% then do not switch element on
    if SOC has dropped below 50% or geyser temp > 75 or MeanBatteryLoad >500W then do not switch on the element (my minimum usage during day is 500w)
    else switch on the geyser element.

    Image of today's usage vs generation bulk load is from the geyser and pool pump, also control poolpump via Sonoff: (you can see i drink too much coffee during the day with the spikes)

    Second image is of a bad solar day, then the geyser element was not turned on by the rules (only by the geyserwise using mains), and the pool pump only ran for short period in the day,
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  21. #17
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    Default Re: Avoiding solar power throwaway

    This is the sad story of RE and grid tie systems. Back in the day the manufacturers developed these advanced inverters that could stay in phase with the grid. Quite a feat! This meant that if one had excess power then you fed it back into the grid (for which you received a credit) and drew from the grid when required.
    Sadly this dream went pear shaped due to RE being predominantly solar and the amount of power being fed back became too much for the grid (causing instability etc.)
    So the utilities are now paranoid of anyone feeding back into the grid even if they do have capacity since they can't dynamically manage the amount of power.
    So the utilities have scared everyone off. I cannot find anyone who is legally grid tied!
    This is my take on the dream that went pear shaped since no one is coming clean (especially those who are illegally exporting to the grid)

  22. #18
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    Default Re: Avoiding solar power throwaway

    Quote Originally Posted by Richard Mackay View Post
    So the utilities have scared everyone off. I cannot find anyone who is legally grid tied!
    ?
    I am sure a lot of People are legally grid tied they Just dont export which is what you want answered.

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  24. #19
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    Default Re: Avoiding solar power throwaway

    There are many of us legally grid-tied and feeding into the grid.

    This month alone I fed in 145kWh of excess power.
    Cheers

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  26. #20
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    Default Re: Avoiding solar power throwaway

    Quote Originally Posted by Fluffy View Post
    There are many of us legally grid-tied and feeding into the grid.

    This month alone I fed in 145kWh of excess power.
    Wonderful!
    At least I can now say I know of one!

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