Part 3: Aggregated supply and demand across multiple households

One of the main problems with looking at demand at the single household level is that demand at this level is very spiky, there are often long periods of low use around 100W and then suddenly a kettle or electric car charger turns on and demand increases by 20-30x in an instant. Solar generation can be very spiky too and so there is room for matching but it can be difficult to get the timing right.

One solution to increasing supply & demand matching at the household level is to have in home battery storage and diversion to hot water stores – but it may not be the best solution for all cases.

Aggregating supply and demand across households provides an example of how the degree of matching can be increased significantly by what could be described as sequential demand. Not everyone boils a kettle at the same time or a cloud passing over one households solar pv system may not be passing over another’s.

In order to explore the extent of increased matching possible through aggregation of supply and demand I have been working with Dominic McCann from Carbon Coop on what could be called a ‘virtual microgrid’ concept, we have a provisional front page for this here - please note that its still in early development:


Read on →

Part 2: Exploring carbon intensity and renewable energy matching


This post describes an approach we have been exploring that uses the MyEnergy emoncms app and work on virtual smart grids with Dominic McCann from Carbon Coop. There’s a good blog and video on what we’ve been working on over on the Carbon Coop blog.

The last post described two approaches to grid carbon intensity that consider the UK grid as a whole. This approach explores what the overall household carbon intensity might be when on-site renewable energy is considered such as home solar but also when renewable energy is bought over the grid, this could be from a green electricity tariff.

If imported electricity is supplied from a 100% renewable energy supplier in the UK: a large portion of the supply will likely be wind energy (54% of good energy’s ‘fuel’ mix comes from wind) and the UK has the best wind resource in Europe. Incorporating grid wind data and exploring matching with wind and solar, means we can really start to test scenarios such as ZeroCarbonBritain in the present.

There is real-time data available on UK wind supply and its possible to scale the total UK wind output in order to estimate a household ‘share of UK wind’ in real-time.

Read on →

Part 1: Attempting to measure and understand the CO2 intensity of grid electricity

Zero carbon energy scenarios such as ZeroCarbonBritain feature significant electrification of energy demands previously provided by fossil fuels such as heating and transport. With electrification it becomes possible to supply these energy demands with renewably generated electricity from primarily wind, solar and backed up by storage technologies from short term stores such as batteries to long term stores such as power to gas.

We do not of course yet have a zero carbon grid. However there has been significant growth of renewable energy and a decline in coal generation in recent years.

The CO2 emissions of demand side solutions such as heat pumps and electric vehicles are significantly affected by the co2 intensity of the supply but in many cases installing and using these technologies make sense at the UK’s present supply mix and can make more or less sense depending on how you calculate co2 intensity and where you assume the additional electricity required comes from.

Read on →

GitHub Submodules

Update: PlatformIO does library management much better then git-submodules, we have switched to using PatformIO to manage library dependencies, see blog posts

Library management for Arduino has always been a bit of a pain; having to go and download and install all the required libraries for various locations on the internet and hope that they are the correct version. Library management becomes even more important when debugging and supporting a project as libraries get changed and updated.

Things have improved in recent years with the increased use of GitHub for Arduino libs allowing changes to be tracked easier and the later version of Arduino IDE including a library manager which can auto-update.

However I have always wanted to have all required libs and files for a particular project all in once place. I feel that I have now found the best solution (for now!).

Read on →

Home Assistant and emonPi

Home Assistant (HA) is a fully open-source home automation platform.

In terms of functionality it’s quite similar to openHAB however it’s architecture is very different it runs on Python 3 as opposed to java.

I found home assistant very easy to setup and configure. It’s got some nice auto detect features e.g. It auto-detected by Chromecast devices. Home Assistant has got pre-built component integrations with many home automation and monitoring devices and platforms. I was also impressed with the presence detection support, I tested using nmap to scan my home router for presence of my phone connected to my home WiFi (indication that I’m home…or I forget my phone!) and OwnTracks MQTT based GPS tracking.

Read on →

Raspberry Pi 3

The latest and greatest from the awesome Raspberry Pi team! An iterative upgrade but very welcome addition of on-board WiFi and a faster processor.

The latest emonSD for emonPi / emonBase seemed to work out of the box with the RasPi3, however it became apparent that something rather important was missing...serial communication with the emonPi's ATmega328!

The emonPi communicates with the RasPi via GPIO 14/15 which on the Model B,B+ and Pi2 is mapped to UART0. However on the Pi3 these pins are mapped to UART1 since UART0 is now used for the Bluetooth module. However UART1 is software UART and baud rate is dependent to clock speed which can change with the CPU load, under voltage and temperature; therefore not stable enough. One hack is to force the CPU to a lower speed ( add core_freq=250 to /boot/cmdline.txt)which cripples the Pi3 performance.

A better solution for the emonPi is to disable BT and map UART1 back to UART0 (ttyAMA0) so we can talk to the emonPi in the same way as before.

Read on →

Outdoor Temperature Data from Weather Underground to Emoncms & MQTT

Monitoring the temperature outside your house is super useful to inform your home automation systems and calculate domestic heating (and dressing!) requirements.

One way is to monitor external temperature is to install your own external emonTH wireless temperature node or use a commercial web-connected weather station. However a cheaper way is to tap into the Internet of Things and connect to another weather station in your area.  Weather Underground have over 18K weather stations online in the USA and a free API for non commercial use.

Here's an example of using nodeRED to poll the Weather Underground API and post to Emoncms (using nodeRED Emoncms flow) and MQTT. Read on →

Heat pump Testing: Initial results

Headline figures
Test period: 17th of October to 7th of February (113.3 days)
Electricity input: 413 kWh (3.6 kWh/d)
Heat output: 1405 kWh (12.4 kWh/d)
COP: 3.4
Electricity input includes: heat pump compressor, heat pump controller and circulation pump.

In late October last year I installed with John Cantors help an air source heat pump at home, I currently live in a small cottage in Snowdonia, North Wales and after several winters of heating with a wood stove and direct electrical fan heaters, its been great having a warm place with much reduced electrical input requirement and wood consumption and its given me a good opportunity to test the technology in order to understand and confirm how well it works, albeit in a building which is far from low energy in terms of building fabric performance.

Here is a photo of  the cottage which gives a good idea of the kind of building it is; for a detailed look at the space heating energy requirements and building fabric see appendix. Read on →

Low carbon energy film featuring OpenEnergyMonitor

A few months ago we were lucky to be contacted by a French film team wanting to feature OpenEnergyMonitor as part of a film about low carbon energy. The film "ACHIEVING 2050 I OPTIMIZE ENERG" aired in November this year.

The film can be watched online here (in French), the part featuring us starts at 28min in: Read on →

Heatpumps in the ZeroCarbonBritain model by the Centre for Alternative Technology.

Following on from last blog post on heat pump monitoring I will try in this post to give a bit of context on heat pumps. Heat pumps are interesting because they provide a way to make efficient use of renewable electricity for heating. They are used in many zero carbon energy scenario's including the ZeroCarbonBritain scenario from the Centre for Alternative Technology which is one of the most comprehensive UK based 100% renewable energy scenarios created.

This sankey diagram from the ZeroCarbonBritain report gives an overview of the energy flows in their scenario, with heat pumps providing the bulk of the heating and hot water demand: Read on →