WEBVTT NOTE Transcript 2024-03-18 from FLAC by https://elvery.net/prototypes/transcribe/ on my MacBook Air M1 on maximum quality setting. NOTE Body lightly edited. 00:00.000 --> 00:02.000 StatsCast 00:02.000 --> 00:07.000 [Intro Music] 00:07.000 --> 00:17.000 Hi, I'm Damon Hart-Davis, and welcome to Earth Notes podcast on all things eco and green and efficient at home! 00:17.000 --> 00:24.000 7th June 2022 for energy storage stats up to and including May. 00:24.000 --> 00:36.000 Many things have happened since the last StatsCast. Upgrades and new systems have gone in here at EOU towers and there is now a new unified way to look at the various energy data streams collected too. 00:36.000 --> 00:40.000 16WW energy series data set. 00:40.000 --> 00:48.000 One thing that I'm happy with and that didn't involve splashing out on expensive equipment is the new energy series data set and page. 00:48.000 --> 01:00.000 All just a SMoC (Simple Matter of Coding)! In fact some slow careful thought, a couple of major scripts, a couple of generic ones and a decent handful of very specific simple data extractors for each data source. 01:00.000 --> 01:08.000 This provides one place to find most of the energy stats from 16 WW. The data are provided in a simple uniform CSV format. 01:08.000 --> 01:15.000 Where there are multiple sources for the same data they are consolidated side by side in a single CSV file also. 01:15.000 --> 01:23.000 Historically the gather data have been in many formats particularly dates and times and this data set largely smooths that wrinkle. 01:23.000 --> 01:29.000 There are still some data that use local time rather than UTC and that isn't entirely fixed yet but could be. 01:29.000 --> 01:36.000 I've already spotted a few errors, e.g. from entering wrong values manually with this and have been able to quickly correct them. 01:36.000 --> 01:37.000 Hurrah! 01:37.000 --> 01:44.000 Anyway please go and marvel at the new page and the data sets CC0 license. 01:44.000 --> 01:46.000 Off-grid battery upgrade. 01:46.000 --> 01:52.000 My off grid battery bank was getting old and tired after a decade so at the start of September I replaced it. 01:52.000 --> 02:00.000 The new one is lower nominal capacity than previously but I think a better fit to energy available and required, especially mid winter. 02:00.000 --> 02:11.000 I stuck with lead acid gel since I have everything set up for it, my Morningstar MPPT controller is great and I still don't see any believable lithium chemistry solar controllers/BMS. 02:11.000 --> 02:16.000 One aside, this would be the first time that I'd recycled any lead acid gear. 02:16.000 --> 02:29.000 I still had my very first gel battery moping on a shelf and it's not the sort of stuff that I could easily walk to the local council's recycling point in the best part of a mile and which is in any case massively unfriendly to visit on foot. 02:29.000 --> 02:39.000 I found online a recycler who came and collected including my old LiFePO4 pack though he was unsure what to do with it and paid a small amount for it all. 02:39.000 --> 02:46.000 He should have made bank on the lead in those heavy batteries over 100kg, the new one is a mere 66kg. 02:46.000 --> 02:52.000 I also tweaked the battery management to be a little more aggressive in dumping, I taking the optional loads off grid more often. 02:52.000 --> 03:00.000 The dump load is currently just the internet router at about 12W but that's 12W free to spill to grid or charge the Enphase or Thermino. 03:00.000 --> 03:11.000 Overall I'd say the system has been working more effectively, e.g. keeping the dump load off mains more of the time, maybe 10% or more extra delivered energy, but I'll keep watching. 03:11.000 --> 03:22.000 Grid tied battery quadrupled. A little after refreshing the off grid storage and after much indecision the Enphase AC battery capacity was doubled. 03:22.000 --> 03:31.000 Though the approximately 250W power was enough to carry most non-heating loads, energy capacity, watt hours was probably on the low side. 03:31.000 --> 03:36.000 Against expansion were cost and additional vampire load especially in winter. 03:36.000 --> 03:52.000 The additional power did allow me to, for example, bring water to the boil, slowly on 6 on the small induction spot front right, without need for PV generation or grid imports and contribute up to about 25% of dishwasher or washing machine or oven demand. 03:52.000 --> 04:00.000 But hardly had that new battery settled in before I was made an offer of two further second-hand units at a nice price. 04:00.000 --> 04:05.000 So I caved and doubled capacity again at the end of October, more than I think is actually optimal. 04:05.000 --> 04:14.000 The vampire draw is now approximately 400Wh per day and we rarely fully cycle the increased capacity, approximately 5kWh, in any one day. 04:14.000 --> 04:20.000 But the approximately 1kWh power covers half the typical high heating loads mentioned above, which is good. 04:20.000 --> 04:26.000 It is now much easier to avoid drawing any significant power to cover them if it's at all sunny. 04:26.000 --> 04:37.000 So far I have stuck with firmware version 5, D5.0.34 because version 7 cuts off unrestricted local read access to system stats. 04:37.000 --> 04:47.000 I do not want to round trip across a sometimes flaky internet more than I need, nor reauthorise manually periodically since I will forget and lose data. 04:47.000 --> 04:57.000 In reality we need about half the capacity, approximately 2kWh plus and twice the power, approximately 2kWh, to more cost efficiently cover our loads. 04:57.000 --> 05:05.000 But that implies a battery charge and discharge rate of C/1 rather than the current C/5, which is a tough call. 05:05.000 --> 05:12.000 I think a significant reduction in grid flows, especially at evening peak, is useful for the grid, but we won't be receiving any medals. 05:12.000 --> 05:23.000 Even at current elevated retail prices, approximately 35p/kWh import versus 5p/kWh export, the financial return is still likely insignificant. 05:23.000 --> 05:26.000 Heat battery gas cut. 05:26.000 --> 05:34.000 A significant entirely new subsystem is the long-tued over heat battery charged by solar DHW diversion and tactical mains boost. 05:34.000 --> 05:43.000 Given that dramatically reducing gas demand seemed like a good idea because of events in Ukraine, we turned off the central heating sooner than usual in early March. 05:43.000 --> 05:52.000 The Fermino went in a couple of days later. Gas demand for March was about 160kWh compared to about 450kWh the previous March. 05:52.000 --> 05:59.000 Indeed our typical 4kWh per day hot water use was trimmed to about half a kWh per day. 05:59.000 --> 06:08.000 No, we won't save money since the loss of payment from exported kWh of electricity is similar to the saving from not importing a kWh of gas. 06:08.000 --> 06:22.000 Is it a guaranteed carbon saver? Not absolutely clear for diversion since often grid carbon intensity of a kWh that we could have exported is higher than the 190g of CO2/kWh of burning gas locally. 06:22.000 --> 06:25.000 But reducing flows of both is probably good. 06:25.000 --> 06:34.000 The system is also designed to allow top-up from the grid when grid marginal intensity is significantly lower than burning gas for heat, usually in the wee hours of the morning. 06:34.000 --> 06:42.000 In general that helps support a market for such electricity out of hours expensive though it is for us on our pricey green all-day tariff. 06:42.000 --> 06:49.000 The system simply falls back to gas if the heat battery runs empty since at that point it will be our lowest carbon option. 06:49.000 --> 06:55.000 Complicated but from the point of view of my family largely invisible they never run out of hot water. 06:55.000 --> 07:02.000 I am nagging them a bit to modify how they use hot water to push down gas use a little further and reduce some waste but we'll see. 07:02.000 --> 07:12.000 And though the predecessor of this unit, the UniQ 6 was suggesting as holding approximately 6kWh I have seen this Thermino absorb 9kWh or more in a day. 07:12.000 --> 07:23.000 Sometimes because there is a draw down during the day but also charging from mains coal to well over the phase change temperature does indeed store well over that rather conservative 6kWh. 07:23.000 --> 07:26.000 The unit is currently branded a Thermino 150. 07:26.000 --> 07:31.000 150 litres of hot water raised through 70 degrees [C] is about 12kWh. 07:31.000 --> 07:39.000 Coming soon. I'm keen to look at some more of our load profiles through the seasons showing the effects of our electrical and heat storage. 07:39.000 --> 07:49.000 Also I'd like to sonify some of the 1 minute data available from the Eddi solar diverter of divert/boost, but also grid import/export. 07:49.000 --> 08:01.000 There's more on my Earth Notes Web site at Earth.Org.UK.