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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 03:51am 25 Apr 2018
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I am a big fan of logging power use for a week or a month before making any changes to a system, just to see what is what.
So just looking at one 24 hour period we can tell a lot.
the yellow bars are not actually solar, I have hijacked that sensor to measure the electric HWS seperately.
the first thing we can tell is there are very few load periods that are over 2500 watts. interesting!!
second is the freezer runs for well more than 50% of the time and chews a lot of power. The fridge is the little wedge shaped pimple on top, they seem to run together a lot. that needs to be fixed.
Third the water heater is poorly insulated and is leaking a lot of heat (those two reheat spikes should not be there, no hot water was used after midnight). so there are two solutions, adjust the timer to come on later and only do one heat of the water tank at night. Or redo the insulation I think it is just pipework that is the problem.
Four, if we ignore the HWS load there is under 5 kwh used from sunset till sunrise so if we add a margin or find out if the weekend loads are vastly different there is the potential to power this house overnight from 7-10 kwh of storage.
Five, the spikes we can see are boiling the kettle 6 times and running an induction cooktop a few times.
so what is the minimum generating capacity that would almost cover the load (assuming we move the HWS to daytime heating and only use solar if we can).
it is going to be daytime direct usage + hot water service usage + battery storage recharge.
in this case 3.5 kwh + 4.5 kwh + 7 kwh = 15 kwh /day
This is our starting point to factor in all the other stuff (weather conditions, power prices, etc etc)
so on the bleeding edge, 15 kwh/ day of generation, 8kwh of storage, a gadget to route solar to the HWS and an inverter that can do 2500 watts for 30 minutes reliably. plus maybe an auto transfer switch to go on grid if the batteries are low.
for places that get a lot of reliable sunshine that is a pretty small outlay for almost 24/7 independence. there would be a few days a year it might need some help from the grid or a small generator and charger.
with a few minor tweaks I think I could get the power usage down from 13 kwh/day to under 9 kwh.
a modern computer, tv and stereo will save 1.2 kwh/day. the hot water service is wasting around 60% of its stored energy, I am confident i can shave 1-2 kwh/day from that. fixing the freezer will save 1.5 kwh/day
That is about $600 saving from a local power bill at the current rates. for direct solar use it is only a consideration for the winter months, we usually have truckloads of spare energy for the rest of the year. Although there is 2 kwh off our overnight storage so we could fit a 6kwh battery or our 8kwh bank would last a lot longer.
the only loads we haven't looked at are, dishwasher heater element washing machine, vacuum cleaner
Once again there are options to upgrade to lower instantaneous load versions if the existing gear is not suitable. Quite a few inverter washing machines play nice with off-grid inverters now. I see mr Dyson is plaguing me with ads for cordless vacuums at the moment. Just saying! they might be crap I havent tried one, but it could be an option, I certainly dont vacuum for more than 20 minutes @ a time. Edited by yahoo2 2018-04-26 I'm confused, no wait... maybe I'm not...
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 05:28am 25 Apr 2018
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For the bit of time a Vacumm is running is it worth worry about what you have? Fisher Paykel top load washing machines are very low power consumption, they a very commen secondhand also. I notice at some stage they changed the lable on the back to sinusoidal AC power only, they must have had warranty issues with square wave inverters or something like that.
I have found our fridge is the biggest drain on the system every day. There are very efficent fridges but the manufacturers don't bother bringing them into Australia. Panasonic make a side by side with ice maker that uses 1KWH per day but the Austalian distributor does not want to know about it.There are only 10 types of people in the world: those who understand binary, and those who don't.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 05:46am 25 Apr 2018
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Vacuum cleaners vary a bit, but an average one would be about 6.5 to 7 amps, say 1.8Kw roughly.
Agree with Mad, the F&P is very frugal with power. I did some detailed data logging a while back, one heavy duty wash on fast spin takes 50 minutes and consumes 83 watt hours. Max peak load is initial acceleration of spin dry where it requires 555 peak watts, but only for a few seconds. One interesting thing with the F&P, it draws about 85 watt hours (over 24 hours) when switched off. The darned thing uses as much power to do one full load as left plugged in but switched off for 24 hours. So don't forget to pull the plug when finished washing.
Modern fridges are usually not too bad, but beware of a very high inrush current when starting up. That can easily bring a very small inverter to its knees. Some inverters can handle that, and some cannot.Cheers, Tony.
davef Guru Joined: 14/05/2006 Location: New ZealandPosts: 499
Posted: 06:35am 25 Apr 2018
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For low in-rush current and quite high efficiency (400W/H per day, model SR254MW) look at the Samsung Digital Inverter series.
I wish they made a smaller one so that I could put it in the off-grid caravan.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 06:48am 25 Apr 2018
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My sister hasnt had a 'proper' vacumn for over a year since the old one blew up, and she has cats! She bought a hoover robot, and had prior a cordless 'stick' vacuum cleaner that she used when dragging the big mains one out wasnt worth the bother
The litle hoover is actually doing a great job, every couple of days she just lets it loose as she goes to work, keeps the cat hair well under control (better than the old mains vac imho) and the stick vac does the corners and spots like under the dining table the robot cant handle well. Both now run off the same charger (18v) as the stick vacs blew up, luckily they are same voltage and plug polarity
After a year, I can say the hoover is doing much better than I expected, only drawback is limited dust (hair lol) collection, and its batterys (nicad) are starting to show signs of issues (motor tone drops after about 1/2 hr- I think a cell is failing/down on capacity- when they fail I am going to look at fitting something better, I dont like nicads that much)
It cost her about $150, and isnt 'intelligent' but seems to work quite well, only issue is as it isnt intelligent, it doesnt go back to base like the $$$ ones do, you have to wander about and find it and plug in for next use
Personally I wouldnt have a 'proper' vacum again after seeing hers in action, does carpets and hardwood floors just fine, even comes with a 'fence' (electronic) to stop it going places you dont want, and it handles steps well as well
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 07:02am 25 Apr 2018
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F&P washing machines also last much longer with the power turned off at the wall. They are suseptable to spikes and and the rectified 240AC causes corrosion of the PCB and OB switch. We use a front loader as they wash better and use 2/3 less water.
No problem here starting anything with my Inverter, only thing I have had it not start was a stalled 5KW AC compressor and that just tripped the 20A breaker.There are only 10 types of people in the world: those who understand binary, and those who don't.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 07:16am 25 Apr 2018
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[quote] I notice at some stage they changed the lable on the back to sinusoidal AC power only,[/quote] Forgot to comment on that.
The F&P does not like spikes or huge amounts of noise on the 230v supply. It will run, but the microcontroller will sometimes crash. The whole washing process stops dead, and you have to power down and power back up to bring it back to life. Its not destructive, just really annoying.
I am sure a decent in line mains filter would fix the problem. But it should not happen with a pure sine wave inverter.Cheers, Tony.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 07:37am 25 Apr 2018
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Robot vacs are great but if you live in brothel like Yahoo they get caught up on obsticals. I have a LG Robo King one and have this problem, works great if you don't have crap everywhere. Have had it strip a little tiny gear in the wheel drive but you have to buy the whole motor for near $100.Edited by Madness 2018-04-26There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 08:12am 25 Apr 2018
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LOL, sounds like me... I havent found any major issues with stuff lying around, anything small and light like shoes just get pushed to the side, anything bigger it just cleans around it. Hey it handles my bedroom OK lol, I call it my bedroom but its more workshop than bedroom atm, piles of those supercheap plastic tubs full of gear stacked against the wall, under the bed, on the bed... So far the hoover has been great, not a single issue apart from a suspected dying cell in the nicads in over a years worth of heavy usage (sis has cats and the amount of fur they shed is incredible)
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 08:36am 25 Apr 2018
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No, but all the larger infrequent loads do have an impact on the capacity of the inverter installed AND the amps draw on the batteries and components.
plus people do impulse buy new toys, it is worth planting the idea that low energy and low peak load appliances could lead to only needing one Tesla power-wall instead of three. Particularly if there is a notorious night owl or early morning "multitasker" in the house. I'm confused, no wait... maybe I'm not...
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:05am 25 Apr 2018
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Okay you are dealing with general public PITA types.There are only 10 types of people in the world: those who understand binary, and those who don't.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 09:13am 25 Apr 2018
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The F n LG robot kept jamming itself under the front of the F n LG fridge, that put a lot of stress on the drive wheels and stripped the gears.There are only 10 types of people in the world: those who understand binary, and those who don't.
Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814
Posted: 10:11am 25 Apr 2018
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LOL- so did you get a new F n LG mini bar fridge 9 months later?
George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308
Posted: 11:43am 26 Apr 2018
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The first thing I notice with quoting power consumption is people rarely specify if they have additional energy sources in their home, IE, Gas.
A modest day in power use at my place is 25Kwh. Everything is electric. Stove and ovens use a surprising amount of power. We have an older fridge and a new one plus a bar fridge I also have a biocycle sewage system that runs 24/7. It's worth about $90 a quarter in consumption alone.
For me, the cheapest option is a big solar system. I can only use electricity for the AC which is a necessity rather than a luxury where we are . It's also the cheapest way of heating especially when I can heat the house through the day from the solar and use little power to keep the place warm over night.
I have set up with used panels and they are very cheap if you keep your eye out. My system is oversize to allow for winter generation. I have about 16 KW in total atm and another 5KW to put up. While it sounds a lot, none of the panels are ideally aligned and tilted although I have my reservations about recommendations on tilt that's for sure. I have Panels Facing south at a shallow angle so while they may not do the normal 4x Kw output, 2-3x still makes the ROI plenty worthwhile especially on Cloudy days.
As unpopular as it will no doubt be with this audience, I'm also not the least bit interested in spending my time worrying about a few watts something uses when not plugged in or spending money that may take years to recoup, if ever, by purchasing something that saves 2 cents a week on power over what I already have. For those Off grid, I can appreciate a more careful watch on the watts but for me having the grid, I'll save what I can and enjoy life which is not worrying about if I can fit an LED light in the fridge to save 10W over the incandescent.
I want to be comfortable, I want to be able to afford my indulgences and a good size solar system allows me to do that. I will have invested less than $2000 on my solar setup with the panels I have ( including the yet to be fitted 5Kw going on the north roof) which where I am, is an average of less than 2 power bills. The used setups have an ROI of months rather than years.
I have the Hot water running indirect off the solar, The voltage monitoring relay Clicks on when the GTI's are producing power and the voltage goes high on the circuit.
I don't know that I NEED a big system but it sure is a cheap way of getting around a lot of other power problems and avoiding stupid high bills.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 12:30pm 26 Apr 2018
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Nope just n F n effed robot.There are only 10 types of people in the world: those who understand binary, and those who don't.
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 10:28pm 26 Apr 2018
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George is quite right, if you have access to natural gas, its vastly cheaper than anything else for creating just raw heat. Cooking, space heating, hot water, and even clothes drying in winter are major energy consumers, and if you can do it all without using hardly any electrical power, it sure cuts down the whole problem...
Fair enough. But I more than halved my overall daily electrical consumption mainly by replacing a very old refrigerator and a huge CRT computer monitor with more recent appliances, as well as numerous smaller changes such as LED lighting and replacing ac wall clocks with battery wall clocks.
Reducing by half my power consumption also halved the required battery capacity, and batteries are going to be the most expensive part of your system.
We all have different circumstances, priorities and expectations. There is no one complete answer.Cheers, Tony.
yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166
Posted: 01:56am 27 Apr 2018
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my experience is the same, I regularly look at families that use in excess of 25 kwh per day and we cut their average use by half with minimal cost and no impact on their daily life. That means either a smaller install or the ability to run larger loads for longer off the cheap solar.
it also gives us the option of running a solar PV powered thermal mass for heating, trying to heat a house by heating the air inside is very poor efficiency unless it is very well sealed.
George you dont need to worry about loads that are rarely or intermittently used, lights that are never on are not worth bothering with but appliances and wall wart power supplies that are a constant 24/7 drain when they idle are wasting power for no reason. I'm confused, no wait... maybe I'm not...
Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406
Posted: 02:20am 27 Apr 2018
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Yes indeed.
Really big Killowatt+ loads only switched on for a minute or two at a time turns out to be negligible in the greater scheme of things. By this I mean things like electric Jugs, microwave ovens and big power tools for example.
What is really bleeding you dry are the ten watt and fifteen watt loads that are on continuously 24 hours per day.
Only a complete energy audit will tell you the truth, and the truth will amaze you.
A 230v electric wall clock that draws only twelve watts works out to 288 watt hours per day. Replace several of those with a battery wall clocks that run off a single 1.5v battery for a year, and that has to be worthwhile.
Its sometimes not difficult to find ten such items around the house that draw constant power even when turned off.
I would much rather spend $4,000 on a battery than $8,000 dollars on a battery twice the size. That is really what it comes down to.Cheers, Tony.
Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498
Posted: 02:24am 27 Apr 2018
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The big difference here George is that Yahoo is talking about systems with batteries, if you just have grid tie and lots of KWH's exported those small loads don't bother you so much.There are only 10 types of people in the world: those who understand binary, and those who don't.
George65 Guru Joined: 18/09/2017 Location: AustraliaPosts: 308
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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