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  • FIRST POST
    • ajbell
    • By ajbell 13th Oct 16, 6:32 PM
    • 784Posts
    • 2,509Thanks
    ajbell
    Excess solar power
    • #1
    • 13th Oct 16, 6:32 PM
    Excess solar power 13th Oct 16 at 6:32 PM
    What do you do with it?.
    I have a diverter so get a tank or two of hot water per day, all battery powered stuff charged, but still end up sending loads back to the grid.
    Any ideas for other uses?.
    Can I connect something else to the second output of my iboost?. Would an oil filled radiator be suitable to be directly wired to the second output and what if it was a 1500w radiator and the excess was more than that?.
    4kWp, South facing, 16 x phono solar panels, Solis inverter, Lincolnshire.
Page 2
    • ajbell
    • By ajbell 14th Oct 16, 9:58 PM
    • 784 Posts
    • 2,509 Thanks
    ajbell
    what about a tea urn?.
    4kWp, South facing, 16 x phono solar panels, Solis inverter, Lincolnshire.
    • rugbyleaguesmate
    • By rugbyleaguesmate 14th Oct 16, 10:18 PM
    • 93 Posts
    • 489 Thanks
    rugbyleaguesmate
    Or maybe a fork lift battery surely there's a way
    6.72kw Pv Ja Solar 280w * 24 panels, Solar Edge inverter, South facing no shading.
    South Lake District, delightful view of Morecambe Bay. Saving up for a battery

    December Solar target 160kw
    • rugbyleaguesmate
    • By rugbyleaguesmate 15th Oct 16, 6:02 AM
    • 93 Posts
    • 489 Thanks
    rugbyleaguesmate
    So reading this post with slightly less rum in my body, it sounds like I need something that diverts the excess electricity I produce and puts it into something that I can benefit from.

    That could be water, heating radiators, a battery anything else?
    6.72kw Pv Ja Solar 280w * 24 panels, Solar Edge inverter, South facing no shading.
    South Lake District, delightful view of Morecambe Bay. Saving up for a battery

    December Solar target 160kw
    • ajbell
    • By ajbell 15th Oct 16, 10:02 AM
    • 784 Posts
    • 2,509 Thanks
    ajbell
    Yes, you need an iboost or similar to divert excess electricity to some other use.
    I have an iboost and it has given me a couple of tanks of hot water every day from spring until this month when occasionally I have to boost it with the gas boiler.
    I don't like exporting power after the hot water tank is hot so am looking at a second diversion into a radiator of some kind.
    Ideally battery storage would be great but not really practical at the moment.
    Am also open to any other ideas.
    4kWp, South facing, 16 x phono solar panels, Solis inverter, Lincolnshire.
    • ASavvyBuyer
    • By ASavvyBuyer 15th Oct 16, 10:36 AM
    • 184 Posts
    • 240 Thanks
    ASavvyBuyer
    So reading this post with slightly less rum in my body, it sounds like I need something that diverts the excess electricity I produce and puts it into something that I can benefit from. ..
    Originally posted by rugbyleaguesmate
    Yes, there are various makes of diverter around. The most efficient ones cost the most, but give you more benefit. But it is a case of working out whether it is economical to do so in terms of the equivalent cost of other sources of energy and the payback time. For example; gas is usually about 2-3p per kilowatt (depending on your supplier). So the cost benefit ratio needs to be worked out on that basis (not how much your electricity supplier charges for imported electricity).
    For us, with West facing panels, we worked out that it was more economical to go for a simpler switching diverter from REUK that diverts power to the water tank circuit whenever we are generating more than we are using for over a minute. It does this by monitoring the red LED on the import meter. If the power then used is too high, causing the red LED to go out or start flashing, it switches the diversion off in less than 5 seconds. That is why we put a 2kw dimmer (off ebay) into the circuit, so that on days of poorer generation, we can limit the amount of power being diverted. Also added a socket in the lounge on the water tank circuit, so that we can plug in the electric oil radiator at this time of year.
    As already said, its not the most efficient diverter, but it only cost £30 and was very easy to install into the existing circuit.
    Rhondda Cynon Taff, 4kw West Facing PV, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • ajbell
    • By ajbell 15th Oct 16, 1:52 PM
    • 784 Posts
    • 2,509 Thanks
    ajbell
    Done it! Wired a 13a fused single socket to the second output and plugged in a 700w oil filled radiator, as soon as the water tank was hot it switched to output 2 and started putting 0.83kw into the radiator.
    Any idea why my 700w radiator draws 0.83kw?.
    4kWp, South facing, 16 x phono solar panels, Solis inverter, Lincolnshire.
    • ASavvyBuyer
    • By ASavvyBuyer 15th Oct 16, 3:11 PM
    • 184 Posts
    • 240 Thanks
    ASavvyBuyer
    Any idea why my 700w radiator draws 0.83kw?.
    Originally posted by ajbell
    They usually draw a bit more than what it says on the box; especially when first starting up, as the element is cold then and has less resistance. Our oil filled radiator, when on the 500 watt setting, usually takes about 600 watts when it first comes on, but then reduces down to about 550 when hot.
    Rhondda Cynon Taff, 4kw West Facing PV, 16 x 8.33 Eternity 250w E+10 panels, Solar Edge SE4000-16A Inverter + P300 Optimisers & REUK Diverter
    + Toshiba RAS-10G2KVP-E Ultra High Efficiency Air Conditioner/Heat Pump
    • silverwhistle
    • By silverwhistle 15th Oct 16, 8:54 PM
    • 1,308 Posts
    • 1,703 Thanks
    silverwhistle
    But it is a case of working out whether it is economical to do so in terms of the equivalent cost of other sources of energy and the payback time. For example; gas is usually about 2-3p per kilowatt (depending on your supplier). So the cost benefit ratio needs to be worked out on that basis
    Originally posted by ASavvyBuyer
    You're right, but my gas costs with VAT over 5p a unit as I'm on a free standing charge tariff. As my total gas bill is still under £40 a year I'm happy enough! Friday was the first day since spring that I've had my boiler on for hot water. I've saved over 3500 units since installation just over three years ago so I reckon my iboost has paid for itself.

    I've had a hot air heater on controlled manually but haven't bothered with the faff of a second diverter. I did turn up the thermostat on the tank though for maximum saving.
    • zeupater
    • By zeupater 15th Oct 16, 11:33 PM
    • 3,485 Posts
    • 4,257 Thanks
    zeupater
    ... my gas costs with VAT over 5p a unit as I'm on a free standing charge tariff. As my total gas bill is still under £40 a year I'm happy enough! ...
    Originally posted by silverwhistle
    ... I recognise that approach as well as those costs and even the total annualised bill ....

    If you're not freezing cold when you're happy, well done ....
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • pinnks
    • By pinnks 16th Oct 16, 10:04 AM
    • 439 Posts
    • 1,026 Thanks
    pinnks
    I agree that gas is cheaper per kWh but do forget the system looses when using the GCH to heat only water. Boiler efficiency compared to an immersion heater, losses in pipes between boiler and tank (and back) and so on. I use about 3 times the kWh of gas to heat water in the summer as I do electricity and can see that using a divert saves me between £70 and £80 on gas over the summer months and possibly about £20 over the rest of the year - and this equates to using leccy unit prices for the diverted kWh
    Wiltshire - 5.25kWp
    3.5kWp: 14 x Phono Solar 250 Onyx, Sunny Boy 4000TL, WSW 40 degrees, June 2013
    1.75kWp: 7 x Phono Solar 250 Onyx, Sunny Boy 1600TL, SSE 45 degrees, March 2014
    • silverwhistle
    • By silverwhistle 25th Oct 16, 2:38 PM
    • 1,308 Posts
    • 1,703 Thanks
    silverwhistle
    ... I recognise that approach as well as those costs and even the total annualised bill ....

    If you're not freezing cold when you're happy, well done ....
    Z
    Originally posted by zeupater

    Thank you. I have no intention of getting cold, even if as a skier I'm used to it a bit. Only just seen this as I've been spending my ill-gained FIT and savings on my cheap fuel bills on a short trip away - not a cruise, might I add..

    In terms of payback on my capital it's very difficult to work out the savings overall. I'm pleased with the bottom line results on my bills but how do I cost the gas I save? Annually put 1120 kWh to water but, as pinnks points out, efficiencies and unit rates/standing charges obscure the issue.
    • zeupater
    • By zeupater 26th Oct 16, 9:31 PM
    • 3,485 Posts
    • 4,257 Thanks
    zeupater
    ... but how do I cost the gas I save? Annually put 1120 kWh to water but, as pinnks points out, efficiencies and unit rates/standing charges obscure the issue.
    Originally posted by silverwhistle
    Hi

    We measured our gas usage for heating DHW by using gas to heat DHW and measuring it .... .... doing it now (between Summer/Winter extremes) should provide a fair reflection of average standing heat-loss and usage. I'd record usage daily for a decent period (at least 1week+1day ??) and ignore day1 readings for the series (because it may not be a typical heat provision) then use that data to calculate your (standardised) daily average gas usage for DHW ... don't forget to turn the proportional diversion off whilst running the test ..

    A simplistic approach but it'll provide the information you need for your particular setup with a fair degree of confidence ... testing over a longer period will provide a better average, but it'll also burn more gas! ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    • silverwhistle
    • By silverwhistle 27th Oct 16, 1:31 PM
    • 1,308 Posts
    • 1,703 Thanks
    silverwhistle
    A simplistic approach but it'll provide the information you need for your particular setup with a fair degree of confidence ... testing over a longer period will provide a better average, but it'll also burn more gas! ...

    HTH
    Z
    Originally posted by zeupater
    Thanks.
    Even that could be an expensive test! Last bill was 6th September and I haven't tripped over a single unit yet, so used less than 10 kWh.

    I could obviously afford to do the test, but as I'm sure you appreciate, it's the challenge of not using gas. Some people here (no name, no pack drill) don't seem to understand that people do, in fact, have positive motivations.
    • jeepjunkie
    • By jeepjunkie 28th Oct 16, 3:01 PM
    • 1,274 Posts
    • 1,263 Thanks
    jeepjunkie
    Done it! Wired a 13a fused single socket to the second output and plugged in a 700w oil filled radiator, as soon as the water tank was hot it switched to output 2 and started putting 0.83kw into the radiator.
    Any idea why my 700w radiator draws 0.83kw?.
    Originally posted by ajbell

    Should get my finger out and do this as well


    Cheers
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