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Thread: Challenger Electricity Supplier - Octopus and their Agile tariff

  1. #11
    Automated Home Legend Paul_B's Avatar
    Join Date
    Jul 2006
    Eastbourne, UK


    I get what you are saying about batteries and I accept that I am an early adopter and won't get back the money I've spent; to me, it is a hobby, an exploration of what is possible and may come in the future.

    The PowerVault battery has a schedule and five settings:
    - Force Charge
    - Only Charge
    - Normal (charge when producing excess power from PV, discharge when solar is insufficient)
    - Only Discharge
    - Force Discharge

    On a daily basis, I can alter the schedule to force charging when the price per unit of electricity is low (normally below 6p per KWh wholesale) then only discharge when the cost of electricity per unit is high (normally above 10p per KWh wholesale). If it is a sunny or light cloudy day then I can set it to normal, whereby the battery will charge when excess electricity is produced (rather than export to the grid and earn next to nothing), but if I turn on the kettle, the washing machine is heating water, etc. the battery will discharge over and above what the PV array is generating, avoiding importing from the grid. Having the ability to set a schedule changes the dynamics of the return on investment, but I'm under no illusion that over 20 years I'll make a loss.

    The downside at the moment is the PowerVault schedule and setting are all all manual. I can see from the web page, using browser dev tools, that they have an API but it is private, undocumented and requires an API key that is generated from authentication. I am hoping that they open up the API in the future. At that point Idratek and Cortex would come into its own; being able to turn things on and off depending on the cost of electricity would be fantastic. If the cost per unit is low or the battery has capacity then appliances come on, but when the cost is high or the battery is low/needs to charge then the load is reduced to essential baseline.

    I see this as an experiment and fascinating. It would mean that we could really move to renewables which suffer from unpredictability, smooth the electricity demand across the day and have really smart, grid-connected homes. But at the same time, it is frustrating because I can't see this happening for the masses.


  2. #12
    Automated Home Legend chris_j_hunter's Avatar
    Join Date
    Dec 2007
    North Lancashire


    Paul - compeletely with you ... interesting, what you’re doing, too ...

    have read through the PowerVault spec’ etc - the optional WiFi / Internet box is enticing (thinking of Cortex) ... then again, several options are said to be not-yet available / arriving soon, and that one’s mentioned only in a diagram ...

    one thing caught me by surprise ... for PowerVault3 the max’ allowed humidity is said to be 60% ... that seems very low ! When I checked Cortex here, to see where we could put one in our house, it told me the RH in our main living rooms was around 65%, in our garage & basement around 75% ... only in Node0 with its 24/7 PC was it usefully below 60% - but there’s no space to spare there !

    experiments ... why not contact PowerValut about being given access in aid of developments - they might well respond positively, and give you what you need to get Cortex doing its bit ...

    we’re into experiments, too - our self-build is one big one ... on the solar side of things we went with solar thermal, using Cortex to make it more effective ... solar-thermal is headlined as being 90% efficient, six times better than solar-PV ... in reality, of course, that ignores some practical details - mostly heat-losses from pipework & thermal stores ... our rooftop manifolds had begun to leak, too, so last year my brother was up on the roof rebuilding them ...

    of course, something similar could be said of solar-PV - practical details like the effects of dust & leaves, losses from the way they are wired & controlled, and inverter life-expectancy ...

    matching supply to demand is an issue for both, too ...

    we left room on our roof for solar-PV, and ran cables in the loft ready for the inverter / controller ... we held back from installing them, but every now & then we have a look to see how they’ve improved, to see if now is the time for us ...

    recent developments do look promising, so we’ve been reading-up on what’s now available ... lots of factors to consider, and the list of new developments is surprisingly long ... efficiencies are up from the 15% most people have, to almost double that ... along with greater effectiveness through more of the day, and coping better with things like dust & leaves, which can be surprisngly detrimental ...

    one thing that came out strongly, was the need to view things holistically - individual ideas & technologies can all-too-easily be significantly offset by other factors & particular site characteristics ... especially when shadows are involved ...

    keeping panels from getting too warm seems to be more than helpful, too, and there seem to be a number of ways of helping with that ...

    PVT vacuum tubes look very tempting - 80% efficient, 20% in electric, 60% in heat, and they look attractive ...

    batteries look to be almost a necessity, with lots of positive developments since last we looked ...

    Standing back, though, do wonder about all this - the greenhouse effect is vital to our existence, we’d be dead without it, and our contribtion to it is only about 6% of the total - do we really understand how it works & what we can do, and do we really have the technologies needed - maybe we will make things worse rather than better ?

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