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In the UK, the majority of domestic electricity customers are on a standard variable tariffs: a contract which the customer can leave any time, with a single price for electricity used any time of day, which the utility can increase with 30 days notice.

A common variant of this is referred to as Economy7, in which there is a lower price for any electricity consumed in a 7 hour window, and a higher price for electricity used the other 17 hours. This tariff is particularly attractive for customers who have electric storage heaters which they can run at night.

Another way in which contracts commonly vary is by having fixed terms, typically 1 year but occasionally 2 years, in which the prices won’t increase. There is often an exit-fee for leaving a fixed term contract early. At the end of the fixed-term period a customer can revert to the standard variable tariff or agree another fixed term, both of which will involve a new price. …

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At the end of each of the last few years, I’ve written a blog post listing the books that I’ve read or listened to over the year (see my 2019 and 2018 lists). I find it a useful way of reminding myself what I’ve read, and of recognising and recommending some really good books. Obviously I’ve got my own particular interests, so don’t feel worry if some of my choices aren’t to your taste.

Here is my list of books that I’ve read in 2020:


Dark Towers: Deutsche Bank, Donald Trump and an epic trail of destruction, by David Enrich. …

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It is commonly perceived that the world has got a lot more argumentative in recent years. When I was younger, I found arguments extremely hard to cope with. Thankfully, over the years, I’ve got better at dealing with disagreement.

My trick is that when I encounter disagreement, I now recognise that it could arise from any of a number of sources. I ask questions that help me identify which of these are at play (bearing in mind that it may be a mixture). By understanding the source, I am able to distinguish between disagreements that can and should be resolved, and those that are best left alone. …

There are now a few different mobile apps to choose from if you’re a customer of Octopus with a smart meter and an iPhone or iPad: Octopus’s own octopusenergy (free), Octopus Energy — Agile Watcher (£0.79), Octopus Energy Watchdog (£0.99) and Octopus Watch (£1.99 — with optional subscription for additional features). Since I’ve now tried most of these apps, I decided to write a review of each of these, to help end users select the best app for them.

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Part of my phone’s homescreen!

It is important to note at the start that with the exception of octopusenergy, these apps are designed for customers on Octopus’s Agile tariff. They can be used by smart meter customers on other tariffs, which will at least tell you your consumption (and what your electricity would have cost on Agile), but you will miss out on much of the value of the app. …

In this post I show how any customer of Octopus Energy with a smart meter can see their energy data and do a bunch of stuff like calculating bills and emissions, comparing tariffs and understanding their usage profile.

Having a smart meter promises easy and reliable access to your smart meter data. The reality is more disappointing: an in-home display that is limited and hard to make sense of, or whatever your charts and tables your supplier decides to offer. And, if you ever don’t trust the numbers they do give you, there is no way to dig into them.

Octopus at least lets you access your data in clever ways via an API, but that’s beyond the capabilities of most customers. Still, it has created a space for developers to create some pretty cool apps and tools. If you are on Octopus’s Agile tariff (in which the price varies every half hour) I’d definitely recommend you get one of Octopus Energy Watchdog (for ios) and Octopus Watch (for ios and android). …

This post explains the ideas behind a website I have built to allow UK owners of smart meters access to their data, in a way that makes that data useful to them. I hope that sharing my thinking with others in the field will generate some useful suggestions and debate.

Key principles

My goal is to build something that makes it free, and as easy as possible for as many people as possible to access their data.

Next, I know that a lot of customers aren’t very trusting when their data is concerned. I want to make it as easy as possible for people to trust the website, and to learn to appreciate the value in having access to their data. To do this, I will take data security concerns extremely seriously. And I will always make decisions in the customers’ interests (rather than, say, in the interests of companies that may want access to customer data). …

I wrote a blog post a couple of weeks ago discussing the challenges of getting the data to forecast hourly day-ahead electricity prices for Great Britain. I concluded that it was always going to be a challenge, especially to verify how well any approach was likely to work. That wasn’t meant to suggest that the challenge was impossible, and this blog post describes a method that produces forecasts, although I can’t yet report how good they are.

I have implemented this model in a python on a server. My code needs a bit of work before I am prepared to make it publicly available, but you can see the results at …

On Octopus Energy’s Agile tariff, I can save money by using electricity at the cheapest times of the day. Often this is just by shifting consumption to the cheapest times of the day, which I can easily do because each afternoon they notify customers of the prices for each half hour the following day. But increasingly I’m looking to save even more by shifting demand from one day to another, which is more difficult because I don’t know what the prices will be on the late day.

There are good companies out there that offer hourly or half-hourly price forecasts — often making use of proprietary weather and electricity systems data. However, I was interested to see if I could do a reasonably good job of forecasting UK electricity prices based on the data that is freely available. …

It has historically been incredibly difficult for UK electricity customers to find out how much electricity they’ve used and when. However, that may finally be changing. In this blog post I discuss some of the past challenges, and review a new service that may finally allow many customers to access their data.

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For the past few years, one of my biggest complaints about the UK electricity industry has been how hard it is for people to find out how much electricity they’ve used and when. Sure, some people just don’t care. …

For some time I’ve wanted to create a dynamic report that would allow me to see how well I am doing in flexing my electricity demand. This post documents my first attempt, and describes some of the conceptual and practical challenges I faced.

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I’m an Octopus Energy customer, with a smart meter. This means I can easily access my historical half-hourly consumption, via their API. I am on their Agile tariff, which means the price is different every half hour, and I make an effort to use electricity at the cheapest times of the day. On some occasions the price even goes negative! My biggest source of electricity consumption is a 150L Mixergy hot water tank, which gives me a lot of potential for flexing my demand to save money. (By flexing, I mean either shifting the time of use, or increasing/decreasing total demand. …


Guy Lipman

Fascinated by what makes societies and markets work, especially in sustainable energy.

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