Discussion elsewhere prompted me to look into what I spent on what you might term my energy smart systems relating to electricity consumption, so I thought I’d document it here.
|1||Solar photovoltaic system (4kW)||£5,500||Bundled with ImmerSUN.|
|2||Powervault battery storage (4kWh)||£2,000||Free installation as part of UKPN trial.|
|3||ImmerSUN management system with monitoring.||£600||Estimate based on today’s pricing.|
|4||Remote-controlled car charger.||£300||Modified used charger from eBay. My own software.|
|5||Raspberry Pi items to make HEMS||£200||My own software.|
|6||Wet goods automation (WIFIPLUG x 2)||£70|
Prior analysis of items #1-#4 in pre-Agile days has suggested a total of 9 years to achieve payback on this investment through use of around 85% of the generated energy. Solar panels are potentially good for over 20 years operation, although I doubt the lead-acid batteries will still be operating for anything like that long.
The combination of item #5 with my Octopus Agile dynamic smart electricity tariff has resulted in my average bought electricity price being 7.75 p/kWh in 2019, about half the UK average. I suppose that I could make the same judgements and program items manually each day, but the HEMS significantly reduces my time commitment to achieve that.
Item #6 is my most recent addition. The sophistication of the algorithm combining the Agile tariff with a simple model of the cycle of each device is such that I would never achieve such a high quality result manually. However the saving is perhaps only a three pence each day so maybe £10 per year on my Agile tariff and thus 7 years to pay for the two smart plugs.
Much of this content is thus around 7 years to payback. The HEMS is potentially much quicker, but relies on having smart systems to control such as battery storage and car charger.