Local monitoring and control of inverter - gaps in understanding

Majordennisbloodnok · 2023-10-10T12:23:37Z

Hi, all My wife and I have reached the next step on our renewable energy journey and I find myself needing to fill in some gaps in my understanding. Your help, therefore, will be much appreciated. The current situation We have an array of 18 solar panels providing approximately 6.5kWp connected to a Growatt SPH5000 inverter and feeding a Growatt 6kW battery - both installed outside on one of our house's external walls. The inverter is grid-connected and we have an export MPAN allowing us to export under an Agile Outgoing tariff with Octopus Energy. We also have an Agile import tariff also with Octopus Energy and we have a SMETS-2 smart meter. The inverter uses a ShineWIFI-S module to talk with Growatt's cloud offering and my wife and I are able to keep track of what's going on both with ShinePhone apps on our phones and tablets and also with a web application of theirs. This has been installed and working fine for just under two years now so we have had a chance to iron out any initial setup wrinkles. What's changed and what we want to achieve About six months ago we switched from one of Octopus' flexible tariffs to their Agile import tariff. It made sense since our battery allows us to avoid the expensive 4-7pm slot and so analysing the figures shows it's a significantly cheaper option for us. That also means, however, that we are now being alerted to plunge prices and there have been several since we switched. We would like to make better use of this and that means having a greater degree of control over the inverter and battery, at least manually but preferably intelligently and automatically. It quickly became obvious we would benefit from a centralised and local home automation provision. Since I work in IT, the many concerns raised on this forum about Home Assistant are largely irrelevant to me since I'm hardly a beginner to computing technicalities and since I also work with someone else who has implemented Home Assistant for their solar array, it seemed a logical choice. As a result, I now have a Home Assistant server running HAOS (the Debian flavour) on an X86-64 PC (a little old but still with an over-embarrassment of resources) and physically connected to a cat6 local area network. Connection to the Internet is via fibre to the premises, so there are most certainly no bandwidth or latency issues, but it is via a fairly commonplace domestic router so traffic logging is pretty much non-existent. The Home Assistant installation is working fine and has been configured to connect to, monitor and, where appropriate, control quite a lot of devices on the network. It also connects to MelCloud to monitor and control our Mitsubishi Ecodan ASHP via a cloud integration. We also, perhaps obviously, have another integration that communicates fairly comprehensively with Octopus' API and so we are able to see a lot of data including the day-ahead half hourly prices once released. The problem is that we should be able to do the same kind of thing with our Growatt inverter but Growatt themselves have a history of putting roadblocks in the way of any home automation systems that keep customers from using Growatt's own cloud offering and user interface. As a result, I am rapidly losing patience with them and my hopes I will be able to integrate with their web API are fading quickly. However, I would prefer not to lose the functionality of the ShinePhone app and related web page since that allows me to occasionally check on the battery/export situation whilst away from home. That means I want to explore what may be possible in terms of creating some way of communicating directly with the inverter over the local network, preferably in a manner that still allows the ShineWiFi module to continue working in the same way it has done to date. In particular, we want to be able to implement logic like "Our battery's full and we can see there will be a period of negative pricing during the night, therefore discharge the battery during a particularly profitable point during the rest of the day and then forcibly recharge the battery from the grid during the negative pricing half-hours." or "the forecast for the coming day is great charging weather but there are some really good export rates duing the morning therefore change the priority so any solar energy produced is exported until x time and then start piling into the battery." What I do know As previously mentioned, I am entirely comfortable with most aspects of IT and in particular the following concepts: IT infrastructure and networking Software development - not Python but that won't be a hurdle using web APIs to both push and pull data I'm also fairly obviously familiar now with what bits of kit we have dotted around and what (at least in a basic sense) they do. What I don't know For someone with a career in technology, I'm also remarkably luddite in some areas. As a result, any discussion in those areas really needs to be basic until the penny drops and I can grasp the...

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Solar Photovoltaic (PV)

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Mars

(@editor)

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07/03/2024 2:40 pm

@majordennisbloodnok 😂 that certainly is a post!

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Majordennisbloodnok

(@majordennisbloodnok)

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Topic starter 07/03/2024 2:44 pm

Posted by: @editor

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@majordennisbloodnok 😂 that certainly is a post!

And there hangs the reason for posting. We didn't set out to create an all singing all dancing integrated system; we just wanted to lower the impact of our energy consumption. The post lays out the logical progression that took us from original starting point to where we are now. My guess is that there will be a lot of people whose story over a couple of years from deciding to go more renewable will in some way mirror our home's evolution.

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 SPH5000 inverter
1 x Myenergi Zappi
1 x VW ID3
Raised beds for home-grown veg and chickens for eggs

"Semper in excretia; sumus solum profundum variat"

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