Our Solar PV Journey

YAML is said to stand for "YAML Ain't a Markup Language". This unhelpful acronym (and brazen use of the old "GNU = GNU is Not Unix" joke) doesn't really help in understanding YAML as it pertains to Home Assistant. Well, in this context, YAML is a way of defining the hierarchical configuration settings that drive Home Assistant. So, suppose we have some settings such as: Lights: Left: Brightness: 4 Colour: "Red" Right: Brightness: 6 Colour: "Green" Fans: Extractor: 2 YAML is just the thing to define such a hierarchical structure. For the moment, don't worry too much what these might represent. Consider, however, that we might want the actual settings (such as 4 or "Red") to be controlled by some variable quantity derived from something else within the system. In this case it would be useful to be able to replace the settings with snippets of Python code. And this is, effectively, what H...

There comes a time, sooner or later, that someting about your solarPV system does not work as expected or simply does make sense. When this happens, your installer or the manufacturer of the equipment may not, unfortunately, be much help. This is when online forums or Facebook groups come into their own. I have found a lot of good information on various forums. As long as you are aware of the shortcomings, they can be very useful. My tips for using them are as follows: There are some very knowlegable people on the forums, but also a lot who don't have much expertise. People like to be "helpful", so be aware that some of the "information" is pure guesswork. Most forums are seldom, if ever, visited by the equipment manufacturers. I have found this to be true even of those forums hosted on the manufacturer's Website. There will be times when you should pick up the phone and try to talk to the manufacturer. Many forums have a worldwide memership. A b...

I have the following automation tasks underway, in various stages of completion: If there is a suitably inexpensive timeslot overnight, use it to top up the batteries to 100%. Using this, instead of solar, will allow more solar to be exported at 15p/kWh. Inexpensive slots during sunlight hours are not as useful because I can't export at the same time as using electricity from the grid. If there is not a suitably inexpensive timeslot overnight, top up the batteries from the grid during the period coming up to peak time (which is usually fairly reasonably priced). Make sure any battery charging from the grid is definitely off before the 4pm-7pm peak rate starts. When the electricity price goes negative, boost the hot water temperature using the heat pump and immersion heater. This is a way of benefitting from being PAID to use electricity and storing a little of it in the form of hot water. Change the colour of a lamp in the kitchen to reflect the current electricity...

Since I already have Solar Assistant running on a Raspberry Pi (Orange Pi, in fact) it is relatively easy to hook up a Home Assistant system using the MQTT broker built into the Solar Assistant platform. Solar Assistant does have some basic automation features now, but not nearly flexible enough to do what I want. Home Assistant is clearly the go-to software for solar tinkerers. The only issue, then, is what to run it on? I decided that I was more interested in the automation than in messing about configuring a Raspberry Pi so I plumped for a Home Assistant Green - a pre-configured platform costing under £90. This device hooks up to my network by Ethernet cable and connects to the Solar Assistant platform (and hence the inverter)over the network using the MQTT Broker built into SA. It is fanless, but has a hefty heatsink on the bottom, which should keep it running along happily. It can be connected anywhere within my network since it does everything it needs to over the network.

As I explained before, I was very wary of automating my system beyond what the inverter could do natively. As a retired elecronics and software engineer there is too much danger that such an endeavour would become a slippery slope. Well, I now have one foot on that slope! What prompted this change of heart? Well, during the last month we had some periods with VERY low Agile prices and it got me thinking about how I use my generated solar power. One way of looking at it is to look at the "opportunity cost" of the solar power generated. The incoming solar power, thanks to the sunk cost of the system, comes in at 0p/kWh. However, I can sell any excess back to Octopus at 15p/kWh. That means that, effectively, any solar that I use is costing me 15p/kWh - inasmuch as I could sell it if I want to. This way of thinking leads me to consider a different strategy: What if I were to charge my batteries on a cheap rate at night and, during the day, export most or all of my solar at 15...

April not quite over yet, but still looking good......