How do you make sense of how much energy you’ve used?

I’m really interested in understanding what methods and tools you use today in order to make sense of how much energy you’ve used, and what all that means.

What tricks do you have up your sleeves? Or how do you put the information we provide in graphs and statements to use?

Graphs have become the norm when illustrating and helping customers understand their energy usage. Do they actually help you understand how much energy you’re using?

Some pretty big open questions there I know, but it would be great to hear your thoughts. Comment below!

20 replies

Userlevel 4
I invested in a 4kW solar system three years ago so try and use daytime generated electricity when I can. We've just had a Tesla Powerwall 2 and Zappi EV smart charger installed too. Because of the way VAT is worked out, w had two 300W panels added to the solar.

The Tesla device has an app to control it and this shows electricity going from the solar system, battery or mains allowing me to allocate where the power goes. Last month 91% of our energy came from the solar system and battery. The odd 9% will be our shower that takes 9.5kW and the battery can only deliver five. I did "emergency" charge the car at the beginning of the month and that will have contributed to the 9% too.

The solar produced over 550kWh last month and I don't think we used more than 400kWh including charging the car. I don't keep exact figures but I have a rough idea of how we are doing.
Userlevel 4
Hi Ben,
The graphical method is a quick and easy way to track usage, although I only have electricity shown, not gas - why is this (is it because I have a smart meter for electricity but not for gas?)
However, I don't spend a lot of time checking usage against billing, as I trust what is provided, and have a basic feel for what looks right and would only delve deeper if it appeared there was an anomaly.
The comparison tool is useful, although I see that it now only gives my comparison to previous years, whereas previously there were some generic national average comparisons (e.g. 3 bed houses), which were interesting to see how I compared, but I suppose there were so many potential variables that it was felt they were not as useful to customers??
On the annual comparison available now, it would seem - tying in to my first point - that this is smart meter related, as my smart meter was installed as a consequence of having solar panels fitted and it would have been useful to have more historic information available to see the true effect of the solar panels.
Userlevel 1
I have tracked my gas and electricy usage via my own meter readings since 2011 in an Excel spreadsheet and use this to check bills, Direct Debits and refunds as switching suppliers frequently forced me to keep careful watch on charges as billing administration in my experience is always poor with any supplier. I now use the OVO IHD and usage on the OVO website to track my usage on a daily basis. The personal calculations I most use are a monthly moving average for usage by KW and price and a twelve month moving average total, again KW and price. I am signed up to two comparison websites to manage switching when necessary and always have my last 12 month total KW usage available to facilitate the processing.

Using this information has encouraged me to buy a tumble drier with heat pump and AA rated fridges and freezers. I have also installed smart heating, Honeywell Evohome, with wireless controlled hot water and radiator thermostats in all rooms, wireless controlled lighting with movement sensors and wireless controlled plugs for recharging points, computers, printers and fans. The results are that our bill for a 5 bedroom house with three people (two retired) is now £12 per month less for gas and electric than I was paying 4 years ago for a three bedroom house with one full time working person.

Graphs are OK for spotting any usage issues but I find OVOs manual usage comparison to previous weeks/months to be really annoying as no defaults can be setup and you have to manually select for both gas and electricity separately. Any usage graph is meaningless without comparison to previous usage levels so why not default them. You also need to provide the specific usage calculations and be clear about how these are done.
Userlevel 4
@Steve587 Yes, you will only get gas usage if you have smart gas meter.

I agree regarding comparisons with national trends being missed. It was quite nice to see you were using less than the average ... and equally worrying when you were using more!

Late last year, disappointed by the lack of any such offering directly tied into OVO smart meters, I purchased a British Gas' Hive gas / electric smart thermometer kit. Once it was finally installed in January -- do not order these things during winter, buy them when installers aren't prioritised repairing broken boilers!!! -- I was riding that thermostat like a computer game addict. :D

Not sure if I saved or expended energy, but it was very nice to be in such control water and heat from the comfort of your mobile mobile devices as you travel and recline.

I log into the OVO website every morning and check my daily electric and gas usage for the previous day and add the day's totals to a rolling calculator which predicts my final monthly bill (less discounts + VAT). A little unnecessary, but I find my formula slightly more accurate than OVO's "Next Bill Projection".
Userlevel 4
This was going to be a simple reply - I use a spreadsheet, and don't find the OVO comparisons that useful. But it turned into a saga.

I have an excel spreadsheet with the information from my bills over the years since I moved in here - October 1994. Separate tabs for gas and electric (also all other regular outgoings)
Prior to that it was all on a list and an A3 sheet of graph paper.

I do look at the OVO Usage page ... it really should default to UNITS not price. You need to educate people that the units used is what drives the cost. I've read many forum posts where customers have complained about their cost because they switched to save money - but because it was much colder they used more power so their bill went up. Yet they still blamed OVO for not saving them money. Wouldn't it be great if you could also show what their own estimate was (as used for switching) and compare to that.

With the increase in switching, and with auto-switching beginning, perhaps the industry needs to make historic records available to users / new suppliers.

The supposed comparison graphs on the OVO site and app really annoy me more than help. It only helps marginally comparing use in June to that one, two, three or four months earlier. Mine varies by seasonal trends, not monthly. What matters is compared to June last year and the year before. BUT then you have to take account of the weather - we had a really cold winter and spring compared to recent years, so everyone's bills will have been significantly higher than last year. I tried to assess the impact of that using public "degree day" data when we had the new boiler put in, because use went UP not down. I don't have the necessary skills or information to do that properly. Perhaps OVO could give us trends in general use?

You change the scale every tab as I move backwards and forwards between weeks, or months, which makes it really awkward to try and follow any sort of trend. Using the compare button gives a line instead of a bar chart - why not a different colour bar chart for prior comparisons? That is how excel does it - different coloured bars next to each other - much easier to understand.

I can't export the information.

I was most upset when my new meter zeroed over 3 years historic data mid June 2017, as I am only just getting prior year data in the annual figures, which will become comparable next month.

The energy breakdown doesn't make sense - all of the June figures add up to £15.43, but the electricity cost was £24.06. The 'i' shows Usage * £19.32, Standing charge * £8.63, totalling £27.95. Please can we have some consistency? Why doesn't breakdown add up to the total? I can't even find any sensible relationship between them - Usage incl VAT is 25% more than the sum of the breakdown.

Over the many years I have monitored consumption, I look for a decreasing trend in UNIT consumption, and have a calculation that works out the averages per day, and the previous 12 months totals and averages. The charting facility with in excel allows me to insert trend lines.

We've always had economy 7 so have washed overnight, and it does show an increased cost if we wash or dishwash in the day. Solar panels means for a few months that cost/benefit is reversed.

It clearly shows that new appliances (on the demise of old ones) have been more energy efficient, and changing all the regularly used lightbulbs to energy efficient, and subsequently to LED had quite an effect.
Adding solar panels has made the most difference to electricity consumption. On 30 June we used NO electricity between 7am and 8pm!

Changing the gas boiler in 2009 from a 20 year old supposedly inefficient one to a modern condensing type had next to no impact on gas use. That is without doubt the most disappointing "energy saving" that I have ever done. It also had a hugely negative impact on the potential for solar panels, as the perceived wisdom at the time was not to include an electric immersion heater - so I cannot use surplus power to heat water.

I would love to have a way of properly viewing the data from the smart meters, but I've found that because we were already conscious of how we use power, it has merely saved a monthly manual reading the meter. However, I now have a quarterly reading of the solar input to the grid.
The remote device was interesting, but did not make us change anything and now languishes in a drawer.
More useful would be a smart plug I can use for individual appliances, and maybe that will come. I am not convinced that our fridge/freezer is as good as it claims.

Perhaps this will help someone.
Userlevel 1
I have a 4Kwh solar installation. I use the web application to check on current output of the panels. I also use a network owl. This should give me the current usage but has never been accurate while we are generating.
I do make use of the Pipit IHD as this gives me a view on when we get to a point where it's worth running those items that draw a large load (washing machine, vacuum cleaner etc).
The online OVO usage displays are ok. The historical information does allow you to see where you were against previous years and confirm that you are still making the best efforts on keeping usage down.
What I would like to see is a tie in for those with Solar installations to be able to see the export values. The smart meter does record this information so it should be possible to provide this information.
With energy suppliers now looking more closely at storage, this information across the customer base would also provide Ovo with useful data.
Userlevel 1
Sorry but I can't see how all this checking makes any difference. If you know which appliances use the most fuel and use them for the minimum time, surely you can't do any more. Unless you invest in additional solar power but then you have to bring installation costs into the equation.

Maybe you can do costing comparison checks with other companies and change supplier if necessary. But then the new company may cheat you in other ways. My last company before OVO sent me an email saying my tariff expired on the 31st and I should renew with their best tariff. I emailed back I wanted the new tariff. They acknowledged but the email had no initials or ref no to say who in customer services was dealing with it. Shortly before the 31st, I received another email from customer services to say I'd not renewed with a new tariff so I was now on Standard Rate. I rang and complained to their premium rate no to complain. They stillsaid there was no renewal. Then I got an email saying that they'd cleared the backlog and my new tariff was now installed. When the bill came, they'd charged me Standard Rate for the 1st and new tariff from the 2nd. I rang to complain. The woman said there was nothing she could do and eventually hung up on me. So they made a fiver from the Standard Rate charge plus money from my wasted phone calls, but lost me as a customer. I changed to OVO who were not the cheapest bit I could contact them for free and were environmentally friendly.

I use low energy bulbs but as I live alone, my TV is probably on 12 hours a day. Two cold callers at my door have said initially that my payment of £104 a month for a 3 bed semi is too high but if they find that OVO is one of the firms on their list, they suddenly find that I'm on the best tariff for the area. Last one said I was on an Economy 7 type of tariff with OVO which I was unaware of.

So maybe it's foolish but I'll stick with OVO because I can contact them easily and they're listed as one of the cheapest.
Userlevel 4
@didge05 You are right that the Pipit 500 does give net electricity usage, so it shows when there is a surplus. If I could get the Pipit information on my phone, that would be wonderful.

I find it far more convenient to use the mobile app that came with the solar panels to see what is being generated, and have an educated guess at whether there is enough left to power the washer or whatever. The OVO app only takes me to the web site where it doesn't have today.
Mind you, after three years I've got a pretty good idea of when we'll have enough surplus power.

My solarEdge app lets me see current power (2.62kWh) and also every quarter hour

I can look back at this day last year (or any day since installation) and see the quarter-hourly generation. It has weekly, monthly and annual summaries, and graphs of those year beside year back to installation. I can export enormous amounts of data from their web site, to use elsewhere.

Userlevel 4
@Yorick I stayed with OVO because their customer service was the best I've ever had, even if their prices didn't match some of the competitors. I'd rather be able to speak to a real person who can actually do something than a script follower.
Userlevel 1

I also have the Solaredge package and find that it is quite useful, however I have also found that it does tend to over report on what is recorded at the generation meter and when compared against the owl which records the solar output more accurately in respect to the meter.

Th IHD sits on my desk so is the quickest thing to use for an accurate view on current surplus when there is one. I agree that seeing the real time IHD info in an app would be quite handy.
Userlevel 6
I have plotted fuel usage on an excel spreadsheet since I moved into the current (no pun!) house in the late 80s; originally using an OWL electricity monitor but reading the gas manually (which continued until I got the OVO smart meter in December last year.

In 2011 I had a 2.82Kwh PV system installed so monitoring had to change, I moved on to an EnviR display fed by their Optismart transmitters (these work by counting the pulses from the meter)
I record the PV generated daily by reading the FIT meter; the original plan was to do it daily for the first year or so then move to weekly and possibly monthly, however, seven years later I still do it daily as the graphs are more interesting. I compare my generation with an original estimate of generation from a PVGIS estimate of solar electricity generation and do monthly comparisons as well as calculating ROI, currently 74.56% at end of year seven. I also compare generation year to year to look for any degredation in the PV panels, none yet! I use the website where you can upload your generation and compare its performance with other systems throughout the world.

In 2014 I installed an Optimmersion diverter which sends surplus PV power to the immersion heater, this has turned out to be a bit of a white elephant as it has only recovered about half its cost in four years and the company has since gone bust.

So OVO installed smart meters as I said in December 2017 and I take daily usage readings from the IHD (a rubbish Pipit).

In April I took delivery of a 2018 40Kwh Nissan Leaf and last week my zappi charger was installed so the car is plugged in and charging from surplus PV power. Since the zappi was installed on 21/6 the car has benefited from 115Kwh charge input of which only 40 came from the grid (16 of which was a fast charge prior to a long journey) all without doing anything apart from leaving the car plugged in, the zappi is an amazing piece of kit!
Userlevel 4
@PeterR1947 Interesting that the water heater wasn't effective. Perhaps I shouldn't be so upset! Next things to investigate are a battery, and a solar water heater - a friend in town has one that works well. Unfortunately our roof is aligned so we get morning and evening sun but it isn't great for midday. Against a 4kWh panel installation, it normally doesn't get above 2.7 at any one time. Our all-time peak momentary production was 3.1kWh. However, June was 545kWh compared to June 2017 of 448.

ROI 22% after 2 years on 4kWh system cost £5995 at the end of October 2015. This year is less cloudy so generating more.

I had a look at, and most of the sites round me stopped inputting data a few years ago. The direct link to UK sites is

Enjoy your Leaf. Electric cars are the future, if they can get battery technology sorted out.
Userlevel 1
I have tried all energy monitors under the sun to keep a track of my energy and found the best one to be the Geo 3, which can show import, export, using, savings and cost, per day per month and per year.

We have two solar PV systems installed at our property the first one is only a 1.44 KWp system facing west and generates 1350 kWh per year. We also have a 2 KW solar PV system on a flat shed roof with a five degree pitch and it has shading issues from a street light on the side of the road, this system generates 1500 kWh per year.

The property is a four large 4 bedroom house with two adults and two grown up children; we use on a daily basis 20 KW per day of electric. Hot Tub doesn’t help.

Before I installed the 2 KW Solar Pv installed and the powerwall 1 battery storage system, I knew from my GEO 3 meter we used 1000 kWh from the 1350 kWh we had generated from the solar panels. So we were exporting 350 kWh per year. I then installed an immersun unit to heat my water with surplus generation from the solar panels.

I would like to point out that the Energy Saving Trust say that the average home using the national average consumption with a 4 kW solar Pv system would use only 500 kWh per year or have a saving of £72 off their electric bill, with a unit price of £0.144 per Kwh. This price of £72 was down graded from what they were quoting a few years back of a saving of £135.00 per year from a solar PV system.

We use about 7000 kWh per year in our home and buy from my supplier about 4500 KWhs the rest comes from our Solar Panels. We still export some kWh but not many.
I have a Powerwall 1 which is 6 kW in storage capacity and I can re charge this from the Sunny Boy Storage inverter when programmed from the sunny portal website. I fully re charge this over Nov Dec Jan and Feb each year from E7 electric and it supplies the house electric during the day time.

I would like to know more about what people are using in the way of electric consumption to the size of the house and the number of people living there.
This is better information OVO could give the normal person when they are looking to buy solar panels and a battery storage system to save on their electric bills.
Userlevel 4
Sorry but I can't see how all this checking makes any difference. If you know which appliances use the most fuel and use them for the minimum time, surely you can't do any more. Unless you invest in additional solar power but then you have to bring installation costs into the equation.

Fair point. It's not for everyone. I think it's more a case of curiosity more than anything else. I use aircon in the summer and dehumidifiers in the winter and it's quite (very casually) interesting to check up on usage trends throughout the year. We are talking a few minutes of the day, just like checking the weather forecast really.
Wow! First of all, would just like to thank you all for such in-depth responses.

Little confession to make, I'm new to the energy sector so reading this thread and other threads on the forum has really opened my eyes to the breadth of methods and tools used to understand energy usage.

The motivation for asking this question is part of a piece of research that we're conducting at OVO to better understand how people compare and use their energy usage data. Our hope being that by learning what people are trying to achieve today might give us ideas of what we can do better.

Some of the major things I've taken from your answers so far is first just how many different tools you all use in order to see and make sense of your energy usage. Secondly, the different ways in which you all use this data is really interesting.

There are a few follow up questions I've got on some of the specific things that some of you have said. I'll list them out below so you can all see them. Please do keep the conversation going and jump in with your own answer if I haven't tagged you.

@Absolute Zero Do you use any other tools, other than the Tesla app, to control your energy/understand how much you're using?

@Steve587 How have you used the comparison tool?

@Abreaders How did the information encourage you to purchase those white goods?

@Rooty Why do you find your formula for predicting next bill more accurate?

@EverythingNeedsAUserName What do you mean by "properly viewing data from smart meters"?
Userlevel 4
At present, no. When SMETS2 comes along, I'll want a smart meter.

With the Tesla app I can see how much solar is being produced NOW, where it is going and how much is going, or has been, to the house, battery or grid. It also gives me historical information for week, month and year.

As I write, the house has used 10.5kWh including 0.5kWh charging the car. The solar has produced 29.3kWh, of which 2.4kWh filled the battery. I have pulled 0.5 kWh from the grid which will be for this morning's showers. The solar is producing 2.4kW which is going to the hob & microwave.
Userlevel 1
For me it’s not all about saving money as these white goods and technologies can cost a lot of money. I’m keen to minimise my energy use but without compromising comfort and convenience, hence going for new more efficient technology like a heat pump tumble drier and energy efficient lighting. It’s really easy to see the increased usage of any tumble drier using the OVO app but this has been reduced considerably by our new heat pump model. The most cost effective system has been the Evohome Smart Heating. I can put each radiator in the house on its own individual daily schedule and also the heating and hot water automatically turns off and on using smart phones when we leave or arrive home. With a large house and busy family this really keeps energy usage to a minimum and the OVO IHD allows me to see the hour by hour effect of these devices and warns me if anything is using large amounts of energy at strange times. Seeing the increased electricity used by our electric blankets last year encouraged me to invest in some relatively inexpensive Kasa smart plugs so that they can be turned on and off automatically or even by Amazon Alexa voice activation. The heating, lights and TV are also be controlled by Alexa and the family are more inclined to turn things off if they don’t have to get up to do it. During this hot summer I’m using these same plugs to control several room fans so we don’t just leave them on all the time.
Userlevel 2
As a brief introduction, I have a smart meter on economy 7 and an EV. I don't have any solar at present.

I find the graphs useful, though I would like the daily breakdown to show cost as well as energy used - this would highlight any problems with timings for economy 7 purposes.

The energy breakdown would be useful, but I find it very inaccurate. My EV should be the biggest useage of energy, but it is showing refrigeration. I know it's wrong because I get monthly useage reports from my charger and ovo are under reporting by around 50%.

I occasionally use the IHD - but this would be more useful if it integrated with my online account and use on my smartphone. (I have the Pipit 500)

It might be useful to have an option of downloading the full half hourly data so that it could be analysed in more detail. But for me I would only do this occasionally and not every month.
Userlevel 4
When the 5 minute? data was available via the website, I used that to check how much electricity my fridge freezer used and how much my 30 year old washing machine uses. I also checked how much to cook a sunday roast dinner, and how much to heat up a midday meal in the electric oven. Also one hour's TV, and lights (some are LED, others are halogen, and some are the original kind. Given that I already turn off lights when a room is not in use, and only wash full loads at 30 degrees, the only saving I found I could make was to use the microwave or gas hob more often for cooking, and only use the electric oven if I could fill it with several dishes.
Now that the 5 minute graphs have been removed, I can no longer carry out this exercise when I replace a broken appliance.
I don't believe the Ovo usage breakdown figures at all. I suspect that they can only recognise the consumption pattern of modern appliances. When my central heating broke several times last winter I used a fan heater a couple of times, and this didn't appear in the usage breakdown.
Having been away for several days, I've just seen that my base usage is between 1.8 kWh and 1.9 kWh each day. That seems a lot for fridge/freezer, router, landline and emonTX and raspberry pi. I'll have to see what's going on there.
Userlevel 4
Wow! First of all, would just like to thank you all for such in-depth responses.

@EverythingNeedsAUserName What do you mean by "properly viewing data from smart meters"?

Welcome and good luck.
Useful comparisons of my data with previous year, with other users, normalised for weather differences...
Graphs that when you compare to previous, use the same graph format.
Understanding use by various equipment in the house. The breakdown calculated down the right hand side doesn't make a lot of sense.
Ability to get what is on the pipit on my smartphone and PC.
Ability to download data so I can then view it in other ways, and keep a long term trend. As I mentioned, I was upset when you deleted all my older information on getting a smart meter (and I was told when I enquired that this will happen whenever I get any replacement meter, even another smart meter).