SteamyTea Posted July 19 Posted July 19 Well I actually bought it towards the end of last year. It was a cheap Asus i5 from AO (brilliant delivery, less than 18 hours). Anyway, I always like to check how much power things actually draw, my last but one laptop was great at 8W, the next one I never checked as it was my Mother's old one and I only used it for a few weeks. This one, I started monitoring on the 5th July at 18:15. Just seen the energy monitor tick over to its first kWh, 337.25 hours later, so that works out at 2.97W. Pretty good I think as it probably gets 3.5 hours of usage a day, but is permanently plugged in to keep the battery charged. If I just assume it has had 50 hours usage in the last 2 weeks, that is still only 20W. Still pretty good.
JohnMo Posted July 20 Posted July 20 Wish my heat pump controller only used that much electricity. It pulls 17W and often bumps up to double that.
Kelvin Posted July 20 Posted July 20 The background load of our house is 600W. It was 800W but I’ve done a bit of optimisation to reduce it.
JohnMo Posted July 20 Posted July 20 1 minute ago, Kelvin said: The background load of our house is 600W. It was 800W but I’ve done a bit of optimisation to reduce it. I am down to about 300-400W (it fluctuates a bit), 2x MVHR units, heat pump always on, treatment plant, UV steriliser for borehole water treatment. Removed 75W by changing the settings on heat pump for the circulation pump, which by default is always on, to on when requested by heat pump internal controller.
SteeVeeDee Posted July 20 Posted July 20 38 minutes ago, JohnMo said: I am down to about 300-400W (it fluctuates a bit), 2x MVHR units, heat pump always on, treatment plant, UV steriliser for borehole water treatment. Removed 75W by changing the settings on heat pump for the circulation pump, which by default is always on, to on when requested by heat pump internal controller. What do you think about your system? I'm pondering about our heating and cooling systems. I'm still at an early stage but I really struggle in the heat overnight during the summer. Considering ac and solar panels to run them.
JohnMo Posted July 20 Posted July 20 I just use UFH in coop and heat mode, keeps house a more stable temp and cools quicker after getting solar gain. When house is hotter than outside we open windows and doors also. Bedroom window is most nights.
Pocster Posted July 20 Posted July 20 15 hours ago, SteamyTea said: Well I actually bought it towards the end of last year. It was a cheap Asus i5 from AO (brilliant delivery, less than 18 hours). Anyway, I always like to check how much power things actually draw, my last but one laptop was great at 8W, the next one I never checked as it was my Mother's old one and I only used it for a few weeks. This one, I started monitoring on the 5th July at 18:15. Just seen the energy monitor tick over to its first kWh, 337.25 hours later, so that works out at 2.97W. Pretty good I think as it probably gets 3.5 hours of usage a day, but is permanently plugged in to keep the battery charged. If I just assume it has had 50 hours usage in the last 2 weeks, that is still only 20W. Still pretty good. That’s not bad . Windows though yeah ? (expletive deleted) it then 😊
SteamyTea Posted July 20 Author Posted July 20 2 hours ago, Pocster said: That’s not bad . Windows though yeah ? (expletive deleted) it then 😊 Would be at least 6kW if a Granny Smith.
Mike Posted July 21 Posted July 21 On 19/07/2025 at 20:36, SteamyTea said: I always like to check how much power things actually draw, my last but one laptop was great at 8W, My latest laptop is powered via USB so, for added geekery, I bought a USB cable with an inbuilt power display It's currently fluctuating from 9W to 12W, though I've seen it top the 60W theoretical maximum when processing large amounts of data.
SteamyTea Posted July 21 Author Posted July 21 4 hours ago, Mike said: My latest laptop is powered via USB so, for added geekery, I bought a USB cable with an inbuilt power display It's currently fluctuating from 9W to 12W, though I've seen it top the 60W theoretical maximum when processing large amounts of data. I have not looked at peak power (the monitor is currently on the kettle), may do that later. What laptop do you have as I thought that USB powering would be useful as it can be easily charged in the car. I currently use a 12V (DC) to 230V (AC) inverter when away.
Mike Posted July 21 Posted July 21 8 hours ago, SteamyTea said: What laptop do you have as I thought that USB powering would be useful as it can be easily charged in the car. I have an HP Zbook, but there are quite a few on the market. USB-C power delivery becomes mandatory for all laptops sold in the EU from 28 April next year, so it may soon be difficult to buy any other type.
marshian Posted July 21 Posted July 21 On 20/07/2025 at 09:38, Kelvin said: The background load of our house is 600W. It was 800W but I’ve done a bit of optimisation to reduce it. I guess it depends on what electrical kit is running mine averages around 300W background load.
SteamyTea Posted July 21 Author Posted July 21 49 minutes ago, marshian said: I guess it depends on what electrical kit is running mine averages around 300W background load. My house used no power half the time, so my background load is zero. This is partly a quirk of metering at the 1 Wh level, but I cannot sample lower than that.
Kelvin Posted July 21 Posted July 21 (edited) 3 hours ago, marshian said: I guess it depends on what electrical kit is running mine averages around 300W background load. A bit like John above. MVHR, ASHP, sewerage treatment plant, two UV disinfectant lamps, two water treatment systems, borehole pump control, DAB water pump, Starlink (quite power hungry) plus a load of computer equipment then the usual household stuff. A lot of that is relatively low power but it all adds up I guess. Cutting it from 800W to 600W was relatively easy so there’s a bit more to come and I have a few unused smart sockets so will be able to power some things down on a schedule. Coincidentally the PV generation on an overcast rainy day matches the house background load. Edited July 21 by Kelvin
SteamyTea Posted July 21 Author Posted July 21 Quite interesting the constant power draws that some people have. While I am not a financial fan of battery storage, if your constant loads are high, they may make financial sense, though it does depend on the cheap, time of use, electricity price.
DamonHD Posted July 21 Posted July 21 4 hours ago, marshian said: I guess it depends on what electrical kit is running mine averages around 300W background load. Mine is more like 150W overnight including all the batteries / diverters / heat pump / monitoring. The battery reduces that to ~10W from the grid.
DamonHD Posted July 21 Posted July 21 Well, in case it helps anyone else knock ~16% (!) off their standing load in two shakes of a lamb's tail like that... Times are UTC. More data/graphs: https://www.earth.org.uk/img/PV/load-profile/202506/
SteamyTea Posted July 21 Author Posted July 21 (edited) I have loaded up my mighty spreadsheet of my energy usage, and looking at the last full 4 years, my breakdown is as follows. This is for an all electric house on Economy 7. Day Mean Power 0.09 kW Delivered Power 0.18 kW % Zero Power 58% Night Mean Power 0.89 kW Delivered Power 1.1 kW % Zero Power 44% The greatest power I have drawn, over a half hour period, is 8.9 kW. During the cheaper night rate, considering there is 3 hours (185 minutes) when no power has been drawn from the grid at all, and I have a 100 A supply, charging batteries would not be at all challenging. When I look at just January, February and December, when I am usually heating the house: Jan Day Mean Power 0.14 kW Delivered Power 0.23 kW % Zero Power 52% Jan Night Mean Power 2.63 kW Delivered Power 3.14 kW % Zero Power 32% Feb Day Mean Power 0.11 kW Delivered Power 0.2 kW % Zero Power 51% Feb Night Mean Power 2.19 kW Delivered Power 2.67 kW % Zero Power 33% Dec Day Mean Power 0.14 kW Delivered Power 0.23 kW % Zero Power 51% Dec Night Mean Power 2.52 kW Delivered Power 3.02 kW % Zero Power 33% So to power my house during the winter days, by charging batteries at night, I would need a battery system that can store a deliverable 2.5 kWh, and deliver a peak of 10 kW. I currently have a 20p kWh difference between day and night rates and looking at my latest bill, which was waiting for me when I came home, I have used 1281 kWh on the day rate and 4538 kWh on the night rate. Those have to be halved as that is for two years, so 640 kWh day, and 2269 kWh night. At current rates that is £215 on Day Rate. If that was on Night Rate it would be £86 a year. So a difference of £130 (with a bit of rounding here and there). Now I have no idea what a suitable system would cost to install, but being generous and assuming that there are only 5% losses during each charging and discharging cycle, and that after 5 years, 90% of the capacity is available, a 3 kWh storage system would be needed and a 10 kWp inverter. Anyone know what that would costs, or to put it another way, it would have to be less than £1300. Edited July 21 by SteamyTea
DamonHD Posted July 21 Posted July 21 From conversations I had recently I think that you could get that spec at *wholesale* prices, but no install nor retail margin. But bulk battery costs are falling very fast at the moment.
DamonHD Posted July 21 Posted July 21 (edited) Not quite! Peaks are actually: DHW top-up by heat pump, DHW top-up from PV, evening meal being cooked, DHW top-up by heat-pump! Please admire the chunk of exports that I've managed to notch out, ie avoid spilling to a busy grid, at noon! FWIW, my laptop is using ~4W. Edited July 21 by DamonHD
SteamyTea Posted July 21 Author Posted July 21 3 minutes ago, DamonHD said: FWIW, my laptop is using ~4W. It is hard to believe a screen can be lit for so little. Here is my lifestyle.
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