Smart Home Energy Analysis 2022

This is my energy analysis for 2022, to assess the impact of my smart home solar installation project. The project was started in October 2022 and my energy analysis page explains in detail how my returns/savings are calculated. 2022 has been beyond my expectations, even with the postponement of our Tesla Powerwall. We have generated a lot more energy than I expected over this winter and so I have been very busy finding ways to use it to reduce our other costs. What follows is a month by month summary:

The shortest day this year is the 21^st of December. The weather is getting colder and we had a lot of days with sub-zero temperatures, some as cold as -7°C. The gas central heating is on and the boiler and pumps can use 180W of electricity in operation. Our Octopus Energy account was credited £66 as part of the Government Discount Energy Bills Support Scheme.

Electricity

• Our historical baseline electricity usage for December is 539kWh.
• The lifetime generation meter read 475.04kWh at the start of this month and 735.51kWh at the end, so 260.5kWh this month. The Enphase system says 257.8kWh and the MyEnergi platform says 265kWh.
• The European Union PVGIS service predicts we will generate 272kWh this month. It is the lowest month of the year.
• We generated 265kWh, an average of 8.6kWh per day, with a low of 0.2kWh and a high of 21.3kWh.
• We imported 470kWh this month (including 124kWh to charge the EV), a 12.8% decrease on our baseline usage. 37.9% of this was at our off-peak rate.
• We imported 346kWh (excluding EV charging), a decrease of 35.8% on our baseline usage and a saving of £54.65.
• To improve our Return On Investment (ROI), I am actually trying to increase our electricity consumption. Our home consumed 450kWh, with a low of 8.1kWh, a high of 24.1kWh and an average of 14.5kWh.
• My 150W smart pond heater came on 9 times this month and was on for a total of 156 hours, using 23.4kWh and costing less than £8.
• My smart oil heater project is now operational and is using free power to reduce our gas usage. Any savings are accounted for in our reduced gas use.
• We have exported 106kWh this month, which would have generated £4.36 if our SEG was in place. If stored in a battery, this would have saved us more.
• Our Monthly Generation Factor is 265kWh ÷ 6.63kW = 40.0.

Gas

• Our historical baseline gas usage for December is 2784kWh.
• We used 2533kWh, a reduction of 9.0% and a saving of £25.90.

Transport

• We have done 4219 miles in our CUPRA Born and 525 miles this month.
• We have used 65.1kWh of free solar energy and imported 124.0kWh on the Octopus Go tariff at 7.5p/kWh, costing £9.30.
• 34.4% of the energy put into our EV is from our solar panels. The rest is Octopus Go cheap night rate at 7.5p/kWh.
• 24.6% of the solar energy generated this month has gone into our EV.
• Petrol averaged £1.57 per litre, so we have saved £90.62 this month.

Summary

The smart oil heater is helping reduce our gas usage. My smart immersion heater controller is still in testing. Hopefully our Tesla Powerwall will be installed soon as this will make a big difference. I've been amazed at how much electricity we generated this month!

Based on last month's data, I re-calibrated my Solcast forecasts to make them more accurate. My forecasts were previously 20.7% over-optimistic, so this is the correction factor I used, resulting in much closer alignment with predicted and generated energy.

This will be our first whole month with solar panels installed. With the clocks going back, the period of generating has started earlier, as well as getting shorter. The weather has also turned cooler. Our Octopus Energy account was credited £66 as part of the Government Discount Energy Bills Support Scheme. I tried to minimise export and get as much energy into our CUPRA Born as possible. We still don't have our Tesla Powerwall but, we haven't paid for it yet either. The smart immersion heater controller is still in testing this month too.

Electricity

• Our historical baseline usage for November is 486kWh.
• The lifetime generation meter read 223.28kWh at the start of this month and 475.04kWh at the end, so 251.8kWh this month. The Enphase system says 248.8kWh and the MyEnergi platform says 255kWh.
• The European Union PVGIS service predicts we will generate 344kWh this month.
• My Solcast forecasts for this month totalled 272kWh.
• We generated 255kWh, an average of 8.5kWh per day, with a low of 0.9kWh and a high of 26.4kWh.
• We imported 573kWh this month (including 214.4kWh to charge the EV), a 10.5% increase on our baseline usage. 50.4% of this was at our off-peak rate.
• We imported 323kWh (excluding EV charging), a decrease of 33.6% on our baseline usage and a saving of £59.39.
• We have exported 113kWh this month, which would have generated £4.62 if our SEG was in place. If stored in a battery, this would have saved us more.
• The Monthly Generation Factor is 255kWh ÷ 6.63kW = 38.5.

Gas

• Our historical baseline usage for November is 2130kWh.
• I have been testing hot water heating using solar energy and cheap rate electricity.
• I have also been testing space heating using free solar energy.
• We used 1367kWh, a reduction of 35.8% and a saving of £78.71.

Transport

• We have driven 3694 miles in our CUPRA Born since collecting it on the 6^th August 2022 and 985 miles this month.
• We have used 67.0kWh of free solar energy and imported 214.4kWh on the Octopus Go tariff at 7.5p/kWh, costing £16.08.
• 23.8% of the energy put into our EV is from our solar panels. The rest is Octopus Go cheap night rate at 7.5p/kWh.
• 26.2% of the solar energy generated this month has gone into our EV.
• Petrol averaged £1.625 per litre, so we have saved £177.96 this month.

Summary

With our Tesla Powerwall installed, our savings would be even greater but, our Return On Investment (ROI) would actually be longer. We exported nearly 100kWh this month, which could have been stored and used at peak times, saving another £40. A battery would also enable all of our electricity import to be at off peak rates, saving us another £100 or more.

At this time of year, it is debatable whether my smart immersion heater controller can do much with any spare solar power as its availability doesn't align well with our needs. I can use it between 03:30 and 04:30 though, to heat water using cheap rate electricity.

This graph shows the daily Solcast forecast v generated energy. Solcast forecasts continually change, right up until the start of each day. These are captured 12 hours out but, my contextual smart home dynamically changes its behaviour as they change. My dashboard always displays the latest figures. The red line shows the downwards generation trend.

Our solar panels and Zappi smart EV charger were installed on 18^th October. Our Tesla Powerwall comes later. We got off to a really good start, generating 32.5kWh on our first day! This is 3 times what we typically use in a day. On some cooler mornings, the central heating was used for 60 minutes to boost the house temperature up to 21.5°C. Our Octopus Energy account was credited £66 as part of the Government Discount Energy Bills Support Scheme.

Electricity

The European Union PVGIS service predicts we will generate 469kWh this month. The Solcast forecasts were 729kWh. From the 18^th to the 31^st we generated 223kWh (an average of 15.9kWh per day), with a low of 2.4kWh and a high of 32.5kWh. Extrapolating this out to the whole month means we would have generated 494kWh.

Our historical baseline electricity usage for October is 443kWh and we imported 411kWh this month, a 7.2% reduction despite using 99kWh to charge our CUPRA Born. 34.6% of our import was at our off-peak rate. Excluding EV charging, we imported 334kWh for household use and most of this was cheap time/rate electricity (a reduction of 24.6%). Our average daily household consumption was 10.8kWh, with a low of 4.8kWh (we were away) and a high of 15.2kWh.

From the 18^th to the 31^st, we exported 130kWh (for which we are not getting paid yet), with a daily high of 27.7kWh, a low of 0.8kWh and an average of 9.3kWh. So, each day we have exported on average close to what our home uses. Extrapolating this out to the whole month means we would have exported 289kWh.

Gas

Our historical baseline gas usage for October is 1220kWh. We used 807kWh this month (a 33.9% reduction), averaging 26.0kWh per day, a low of 10.2kWh and a high of 39.1kWh. We were billed £83.16 for gas this month (excluding standing charges). This equates to a saving of £42.62.

Transport

We have done 2709 miles in our CUPRA Born, with 1009 miles this month. The slow charger has been used 4 times, costing £7.12. We imported a total of 99.5kWh to charge the CUPRA Born. We also did a long trip to Malmesbury and used public chargers, so we have spent a total of £43.30 on charging this month. Petrol has come down in price to about £1.63 per litre, so we have saved £156.08 this month and £510.51 so far in 2022.

Insight & Learning

• I need to recalibrate my Solcast forecasts, as they over estimate our generation.
• Our average daily import was 12.7kWh before our solar panels were installed. After they were installed it was 11.3kWh, an 11% reduction. Our solar panels mean we import much less during the peak time/rate period though.
• If we had had solar panels for the whole month, our estimated import would have been 350kWh, which is a 23% reduction on our historical usage, even without the Tesla Powerwall installed.
• Our average daily export was about the same as our home consumes each day! I plan to install more methods to use this excess very soon.
• With our Tesla Powerwall installed, we would not have imported any electricity at all, been able to run our CUPRA Born using solar power alone and also managed to export some energy at peak times/rates.

The weather has become much more Autumnal in the second half of this month, with a lot less sunshine and some much needed rain. Temperatures have dropped, with night time temperatures dropping below 10°C. In the last week of the month, the central heating was used for 30-60 minutes in the morning to boost the house temperature up to 21°C.

• We used 361kWh of electricity this month, averaging 12.1kWh per day, with a low of 8.4kWh and a high of 23.4kWh. We were billed £131.68 for electricity this month. The slow EV charger accounts for a few high peaks in our daily usage. Using the slow charger over the 4 hours of the Octopus Go cheap rate adds 8.65kWh to our daily electricity usage, almost doubling it. This is costs 7.5p/kWh on this tariff, which is just 65p.
• We used 663kWh of gas this month, averaging 21.1kWh per day, with a low of 12.0kWh and a high of 40.6kWh. The cost is £46.66 + standing charges of £8.16. The higher daily peaks are due to the heating being used briefly in the last week of the month.
• The European Union PVGIS service predicted we would generate 648kWh this month. The Solcast forecasts were 795kWh, with a daily average of 26.5kWh, a low of 10.5kWh and a high of 44.6kWh. The highest power forecast was 6.60kW.
• We have now done 1700 miles in our CUPRA Born and 985 miles this month. The slow charger was used 4 times overnight, using 4 × 8.65kWh × 7.5p/kWh = £2.60. Petrol has come down in price to £1.65 per litre, so we have saved £194.07 using free electricity this month and £354.43 so far in 2022. I've done four round trips to Stansted airport (58 miles away) this month, charging to 90+% and returning home with about 40% battery remaining.

• We used 346kWh of electricity this month, averaging 11.2kWh per day, with a low of 8.8kWh and a high of 15.9kWh. This bodes fairly well for our single Tesla Powerwall (13.5kWh usable storage) but, I'd like to get these numbers lower. It is inevitable that they will go up during the colder winter months because the central heating pump will be running, lighting will be on longer and things like our conservatory dehumidifier will be in use. The tumble dryer will get used over the winter months too and this is the most energy greedy appliance in our home.
• We used 460kWh of gas this month, averaging 14.8kWh per day, with a low of 8.5kWh and a high of 22.6kWh. The cost was £33.78 + standing charges of £8.44. This is spend purely on heating hot water at this time of the year, though my smart home does exercise the central heating once a week, for just 10 minutes. This is actually noticeable in the data.
• The European Union PVGIS service predicted we would generate 735kWh of electricity this month, with a daily average of 36.0kWh, a low of 15.9kWh and a high of 48.6kWh.

• We picked up our CUPRA Born on Saturday 6^th August. Petrol was £1.85 per gallon on average. We drove 715 miles using only free electricity, saving us about £160 in petrol.

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Further Reading

My Features

• Improving Solar Energy Return On Investment
• How To Save Energy

My Projects

• Smart home solar energy project.
• Smart home energy modelling project.
• Smart home energy management project
• Enphase Microinverters In My Solar Energy Project
• Tesla Backup Gateway smart home integration project.
• Smart solar immersion heater control project.

My Reviews

• Tesla Powerwall review
• Smart meter review
• CUPRA Born V2 review
• Zappi smart EV charger review