Bobster. Posted July 17, 2019 Share Posted July 17, 2019 (edited) Having access to monitoring the inverter has given me some insights into where the electricity in our house goes and when. And some surprises. I had been told by several people that refrigerators consume a lot of power. Well, that's not what the apps and web sites I have access to show. We have two fridges and a deep freeze that run all the time, and at night our consumption never goes over 500 w - that's with TVs on standby, with the electric fence running and other minor drains. Now is it possible that they cause a spike when they turn on, but it's so brief that the apps can't catch it? Our heat pump has become my sworn enemy, though tests I did on the weekend shows it uses substantially less than a geyser element. Anyway... that seems to use about 1.5kw when the compressor is running. This is where the playing of games starts. I noticed increased usage on the days in which our housekeeper is in. Not surprising, because she has to use appliances to do her job. But some of those devices chew up the power. In particular I was seeing a big spike about 2:30 every afternoon - sometimes up to 5kw. This worried me because it's more than the inverter can handle if we are running on batteries alone. Long story short: The heat pump (which is on a timer) was kicking in about the same time she does the ironing. I reprogrammed the heat pump and the load is now more evenly distributed time wise. (I checked the labeling on the iron - 2.4 kw!) So these are the games to play now. I suspect I have already solved the major problems, and our daily usage of municipal power now averages about 0.75 kw/h. I have programmed the pool pump so that it doesn't run when Mary is likely to be busy with vacuum cleaners and such. I have reprogrammed the heat pump and dropped the figure at which the battery must recharge from the grid from 50% to 40%. My inclination is to tinker endlessly, but people have to live their lives and do what they need to do. On one occasion I noticed the load drop all the way down to about 11w momentarily. Serendipity, I suppose, with all the fridges being idle at the same time. That suggests the electric fence doesn't consume much at all. Edited July 17, 2019 by Bobster clarity Mark, Chris Louw and Youda 3 Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted July 17, 2019 Share Posted July 17, 2019 15 minutes ago, Pietpower said: A single 3.5kWh Pylontech can only give me 1.4kW. Piet may I ask why you say this, I dont understand this at all? Quote Link to comment Share on other sites More sharing options...
seant Posted July 17, 2019 Share Posted July 17, 2019 Adjusting the charging point or the amount supplied by the grid or when and how long the geyser comes on for and so on and so on, seem to be the joys of being able to monitor your system . Trying to squeeze every last bit out of the system in order to get away from Eskom without breaking the bank. Youda 1 Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 12 minutes ago, seant said: Adjusting the charging point or the amount supplied by the grid or when and how long the geyser comes on for and so on and so on, seem to be the joys of being able to monitor your system . Trying to squeeze every last bit out of the system in order to get away from Eskom without breaking the bank. Lol. Yes indeed. One challenge remains for me. In the morning the system is using the panels for all it's worth so as to get the batteries charged. But SOC reaches 100% by 12:30 latest, and after that the panels just service the load. Which means I am not using them to the max. So I need to try to find something to use all that free power in the afternoons. Quote Link to comment Share on other sites More sharing options...
DeepBass9 Posted July 17, 2019 Share Posted July 17, 2019 (edited) I was also under the impression that fridges and freezers used a lot of power (until I measured), but they only change the temperature by 10 or 20 degrees, compared to a oven or a geyser which heats things up by tens or hundreds of degrees. Edited July 17, 2019 by DeepBass9 Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 43 minutes ago, Pietpower said: Playing the same games. From the other thread I understand you are also using a Goodwe hybrid? The inverter can handle 5kW backup and 5kW grid side giving a 10kW total but with eskom and enough connected to grid side your curve can go much higher even. Yes, it's a Goodwe ES. My understanding, which may be incorrect, is that it can handle a steady 4.6 kw and then an extra 10% (which gives 5) for 60 seconds - on the backup side. Hence my concern. The loads I was seeing were more than the system could handle during a grid outage. So I wanted to address that. I didn't want my housekeeper inadvertently plunging the whole property into darkness. Which begs a question: What does the inverter do when that peak load is exceeded? Does it stop and need to be reset? Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 (edited) 6 minutes ago, DeepBass9 said: I was also under the impression that fridges and freezers used a lot of power (until I measured), but they only change the temperature by 10 or 20 degrees, compared to a oven or a geyser which heats things up by tens or hundreds of degrees. Well, they operate in a similar way to my heat pump (which is really just an aircon in reverse). My heat pump draws a lot less than a geyser, and it's much bigger than the freezer or the fridges. This may be received but outdated knowledge. 30 years ago they may have used a lot of juice, but modern fridges will have more efficient circuitry and better insulation. My newest fridge (LG) has a variable speed motor. Edited July 17, 2019 by Bobster clarity Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted July 17, 2019 Share Posted July 17, 2019 6 minutes ago, Pietpower said: I only got 1.4kW from the battery. Presume it is the inverter that is set that way instead of giving 1.7kW. This to me is a problem. I never knew that Goodwe limits it this much. From a possible 1776 w to 1400 w, that's a serious waste.... Quote Link to comment Share on other sites More sharing options...
Youda Posted July 17, 2019 Share Posted July 17, 2019 22 minutes ago, Jaco de Jongh said: This to me is a problem. I never knew that Goodwe limits it this much. From a possible 1776 w to 1400 w, that's a serious waste.... Might look look like a waste, but when taken from the other side, it's a kind of a protection for the longevity of the batteries. If one is using a hybrid inverter, it's actually cheaper to suck a few high power spikes per day from the grid then trying to cover everything from the batteries. This way, the batteries will live longer and will retain their nominal capacity so you don't have to change them prematurely. I can imagine, that if you disable the grid, GoodWe inverter might pull all the required power from the batteries...as it's just a matter of firmware logic Quote Link to comment Share on other sites More sharing options...
Jaco De Jongh Posted July 17, 2019 Share Posted July 17, 2019 7 minutes ago, Youda said: retain their nominal capacity so you don't have to change them prematurely. Hi Youda, I thought that is why the manufacturer recommend using the battery's at max 37 amp. (1776 watt). Victron for example allows you to discharge the 37 Amp as per recommendation as long as Grid is available. Do you think following the manufacturers recommendation will lead to premature failure? Quote Link to comment Share on other sites More sharing options...
Youda Posted July 17, 2019 Share Posted July 17, 2019 To be honest, my opinion is like this: - US3000 is using 74Ah pouch LPF cells. - Predicted life is more than 4500 cycles and 10 yrs. - Pylontech "recommended" charge/discharge is 37A....which translates to exactly 0.5C. While the LFP technology can survive daily operation at 0.5C, we all know that it's much better to aim for 0.25C, if possible. Especially if you don't want to experience capacity loss, pouch swelling, lithium dendrides and micro-cracks in the electrodes. I do perfectly understand, why Pylontech put 0.5C as a recommended current in their specsheets: primary, a specsheet is a sales tool that is intended to support a buying decision. Not all the values in specsheet, even when marked as "recommended" are really the optimum operational conditions. Long story short: I would never design a PV system that would be cycled at 0.5C every day, having all the usable capacity of the batteries charged/discharged within 2hrs. Would you? Jaco De Jongh 1 Quote Link to comment Share on other sites More sharing options...
PaBz0r Posted July 17, 2019 Share Posted July 17, 2019 I see the Battery Test Centre have released the latest report and the pylon is beating the others with capacity fade: http://batterytestcentre.com.au/wp-content/uploads/2017/07/Battery-Testing-Report-6-June-2019.pdf Youda 1 Quote Link to comment Share on other sites More sharing options...
Youda Posted July 17, 2019 Share Posted July 17, 2019 (edited) @PaBz0r oh yes! From all the lithium batteries available today, I would say that Pylontech is one of the best "bang for the buck". I'm personally using 7 x US3000 in my setup too. One thing to mention - BatteryTestCentre methodology is to set all the values (voltages, currents) according to the SOP of the respective manufacturer. It's horrible to see that for example quite expensive LG ReSu failed hardly, despite of all the "recommended values" were used in the testing. Which reinforces the fact that you simply can't beat the physics and the chemistry. EDIT: By the way, do you still remember those Lead Acid Dual-Purpose batteries and other fancy product names? At the end of the day many users found that Lead-Acid is still just a Lead-Acid... Edited July 17, 2019 by Youda Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 3 hours ago, Youda said: By the way, do you still remember those Lead Acid Dual-Purpose batteries and other fancy product names? "Deep cycle"? Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 5 hours ago, Pietpower said: I only have one fridge and not sure what to make of this graph. The power curve at night is either at 144W or 207W. Presume this is due to the fridge switching on and off but can it only draw 60W when running? OK... my usage overnight varies from 144 to an occasional high of 464. I presume everything else (TVs, decoders on standby, phones charging etc) is constant so the 320 w fluctuation is due to the fridges (all turning on and off at different times). That gives about 100w each. One of these is actually a deep freeze and I'm guessing that draws more than a common or garden refrigerator. I need to check the plates on those devices that declare power consumption. Youda 1 Quote Link to comment Share on other sites More sharing options...
Youda Posted July 17, 2019 Share Posted July 17, 2019 28 minutes ago, Bobster said: "Deep cycle"? Oh, the Deep-cycle and/or Traction batteries are legit....if they are real. But Dual-Purpose and Calcium are just a bit better cranking batteries, nothing more Quote Link to comment Share on other sites More sharing options...
Youda Posted July 17, 2019 Share Posted July 17, 2019 @Pietpower, @Bobster, I'm collecting the online power-stats for almost every electric appliance that I have. As you already found, the average consumption of the fridge is not really high. But when deep-freezer kicks-in, or ice-maker, the consumtion will jump significantly. I can see that whenever I put a fresh hog into my deep-frezer Fridge: Dishwasher running at 70°C mode: Quote Link to comment Share on other sites More sharing options...
Bobster. Posted July 17, 2019 Author Share Posted July 17, 2019 1 hour ago, Bobster said: OK... my usage overnight varies from 144 to an occasional high of 464. I presume everything else (TVs, decoders on standby, phones charging etc) is constant so the 320 w fluctuation is due to the fridges (all turning on and off at different times). That gives about 100w each. One of these is actually a deep freeze and I'm guessing that draws more than a common or garden refrigerator. I need to check the plates on those devices that declare power consumption. What I don't get is why I have a minimum of 144 at night, but it can get down into the 90s during the day. But maybe that's the DC battery power being converted back into AC - which is output but not really load. Quote Link to comment Share on other sites More sharing options...
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