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Making best use of Agile with a battery and ASHP

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(@jamesw)
Eminent Member Member
80 kWhs
Joined: 1 month ago
Posts: 7
Topic starter  

I'm new to the forum, and finding the existing posts very helpful in planning my system. I have solar PV already, and am in the early stages of planning to change my heating from gas to an ASHP (probably >10kW) and battery storage (maybe 13kWh or thereabouts). No EV (or at least I have no off-road parking to add it to my domestic mix).

I'm attracted by the Octopus Agile tariff and the possibility afforded by using a battery to avoid the peaks in prices. I'd be very interested to hear how people do that in practice - do you do it manually (e.g. by manually choosing when your battery will charge / provide energy), or do you use some automated system?

It seems to me that there are several factors that would affect when to charge, including the Agile prices, anticipated ASHP (and non-ASHP) power use through the day, and to an extent anticipated PV generation (although I'm most concerned about the winter situation when generation is minimal).

I've read about a couple of people who use home-brew systems to automate this. I'd love to do a project like that if I had the time but I don't at the moment. I'm also aware that the GivEnergy web portal for its battery systems has some sort of integration with the Agile API, but I can't find any information about it. Does anyone use that? How sophisticated is it - for instance, will it take into account expected ASHP power demands, which may vary a lot from day to day depending on the weather?

Also, forgive my ignorant question, but in terms of programming a battery storage system to charge / store charge / provide power, is it actually the attached inverter that needs to be programmed to do this? I know that some systems (e.g. Powerwall, GivEnergy) have an inverter as part of the package. In other cases I understand that they can be from separate manufacturers (e.g. a Fronius inverter with BYD batteries). In the latter case, is it the inverter that has to provide the interface (through e.g. an app or API) to permit programming of battery behaviour?


   
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Toodles
(@toodles)
Noble Member Contributor
5848 kWhs
Joined: 2 years ago
Posts: 906
 

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. 

This post was modified 1 month ago 2 times by Toodles

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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Majordennisbloodnok
(@majordennisbloodnok)
Noble Member Contributor
4377 kWhs
Joined: 2 years ago
Posts: 380
 

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.

This post was modified 1 month ago by Majordennisbloodnok

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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Toodles
(@toodles)
Noble Member Contributor
5848 kWhs
Joined: 2 years ago
Posts: 906
 

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

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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(@jamesw)
Eminent Member Member
80 kWhs
Joined: 1 month ago
Posts: 7
Topic starter  

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.


   
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Majordennisbloodnok
(@majordennisbloodnok)
Noble Member Contributor
4377 kWhs
Joined: 2 years ago
Posts: 380
 

@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).

This post was modified 1 month ago by Majordennisbloodnok

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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Toodles
(@toodles)
Noble Member Contributor
5848 kWhs
Joined: 2 years ago
Posts: 906
 

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

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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Majordennisbloodnok
(@majordennisbloodnok)
Noble Member Contributor
4377 kWhs
Joined: 2 years ago
Posts: 380
 

Posted by: @toodles

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

He, he.

Most decidedly not. They represent entirely renewable henergy.

 

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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Toodles
(@toodles)
Noble Member Contributor
5848 kWhs
Joined: 2 years ago
Posts: 906
 

@majordennisbloodnok Eggsellant!

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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Majordennisbloodnok
(@majordennisbloodnok)
Noble Member Contributor
4377 kWhs
Joined: 2 years ago
Posts: 380
 

Posted by: @toodles

@majordennisbloodnok Eggsellant!

Nah. I'm just winging it.

 

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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Toodles
(@toodles)
Noble Member Contributor
5848 kWhs
Joined: 2 years ago
Posts: 906
 

@majordennisbloodnok Treading on eggshells then?

Toodles, 76 years young and hoping to see 100 and make some ROI on my renewable energy investment!


   
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Majordennisbloodnok
(@majordennisbloodnok)
Noble Member Contributor
4377 kWhs
Joined: 2 years ago
Posts: 380
 

Posted by: @toodles

@majordennisbloodnok Treading on eggshells then?

I try to ovoid doing that...

 

105 m2 bungalow in South East England
Mitsubishi Ecodan 8.5 kW air source heat pump
18 x 360W solar panels
1 x 6 kW GroWatt battery and inverter
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; suus solum profundum variat"


   
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