Hello Jamesw, I’m in a similar situation as I have 8.1 kWp. of PV, 27 kWh of Tesla Powerwalls and I’m very much in favour of the Agile tariff. I have an 8 kW Daikin ASHP and a Sunamp Thermino ePV20 for my DHW needs. I did swap to Cosy tariff for a few months then swapped back to Agile; I found the timing of the cheap rate did not fit in as well as the Agile regime due to them not being symmetrical leaving a longer gap from 16:00 to the next morning for the next cheap slot.

I manually programme my Tesla app to gorge one the cheapest hours and though this takes a few minutes to do each day, I find it very satisfying finding the cleanest / cheapest times to charge the battery. I don’t know of any app that can work with my OE API and the Tesla app though OE are talking about extending the ability to integrate other storage than just GiveEnery systems. My MyEnergi Eddi is programmed to charge my DHW system during the early hours as this is usually some of the cheapest times on Agile. The Tesla integration of inverter in the Gateway keeps it all neat and I have mine set to allow discharge to grid if I wish to and this comes in very handy when Agile rates are very favourable (even plunge or negative pricing sometimes!) I have no knowledge of the other battery systems as I went for the Tesla from the start. Regards, Toodles. 

Hi, @jamesw. I have the pretty much classic mix of an air source heat pump, solar PV and a battery alongside Octopus agile tariffs for both import and export. I settled on managing the mix with Home Assistant, so it was not a huge time investment to get things set up and even less of a financial investment given it’s open source software.

I have several rules set up that govern how things do what and when. I won’t go into exhaustive detail but for example:

• If the import price goes negative the battery will charge from grid.
• If the import price turns positive and the battery is set to charge from grid then this setting is turned off.
• At 4pm (the start of the expensive period) the battery will be told not to charge from grid.
• I have somewhere to set a date and time manually so that when that point is reached the battery will charge from grid. This means I can make off-the-cuff tweaks to ensure a full battery ti tide us over the expensive stretch.
• If the import price goes negative and the hot water tank is not up to temperature, tell the heat pump to work on DHW.

These are some of the decisions I’ve automated but I can, if I want, take into account the weather forecast, the solar PV forecast, whether or not there’s anyone at home and so forth. At the moment the few rules I’ve got in place cover the bulk of the efficiency maximisation sk what I have left outstanding will steadily provide fewer and fewer extra returns.

@majordennisbloodnok EMNTK what kW rating do the hens have? 🤔 Toodles.

Hi @toodles and @majordennisbloodnok, many thanks for your helpful replies. I have been contemplating using Home Assistant if a suitable off-the-shelf control solution isn't available, so it's good to know that this approach works and that there's an integration for GroWatt inverters. Your combination of rules with a possibility of manual override looks like a very practical approach.

I shall try to establish what other inverters are supported on Home Assistant, since it's not immediately obvious from its integrations page. Somewhat surprisingly, given the well-documented GivEnergy API, I can't see a GivEnergy integration. Also it's not clear to me whether the Fronius integration just allows polling of data, or also control of batter charge/discharge.

@toodles, it ranges from just a few clucks to 7 or 8 kiloSquawks depending on whether mealworms are available or not.

@jamesw, it’s worth bearing in mind that the standard Growatt integration works through Growatt’s API which is patchy at best. If you want to manage locally (I do) then one of the community integrations is the ticket. It also happens that there are certainly similar community integrations for GivEnergy; I’ve just looked. There are likely to be integrations for most of the popular inverter brands so I would focus on which inverter/battery will suit your needs and then check compatibility with Home Assistant afterwards - tail, dog, wag, let’s get the order right 😉.

Bear in mind too that although many of us download and install Home Assistant onto a spare old computer we may have picked up from somewhere, it is also possible to pick up a pre-installed Home Assistant box (Home Assistant Green, for instance, at £86).

@majordennisbloodnok Does that make them ‘Battery Fed’? 😉

Posted by: @toodles

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@majordennisbloodnok Does that make them ‘Battery Fed’? 😉

He, he.

Most decidedly not. They represent entirely renewable henergy.

@majordennisbloodnok Eggsellant!

Posted by: @toodles

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@majordennisbloodnok Eggsellant!

Nah. I'm just winging it.

@majordennisbloodnok Treading on eggshells then?

Posted by: @toodles

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@majordennisbloodnok Treading on eggshells then?

I try to ovoid doing that...