Q-Dog
¯\_(ツ)_/¯
Ran my fridge 2 weeks through a KillAWatt and the usage number I got was nearly identical to the energy guide estimate. Samsung with bottom freezer and digital controls. Freezer runs at 0ºF and the fridge section at 36º.
Refrigerator real consumption versus energy guide estimate
- Thread starter Mcgivor
- Start date
New EU energy ratings dropped A++ fridges to C or D rating.
I have been keeping eye on efficient fridges and now actually saw first EU2021 A-rated model.
www.wermuth.de
330 litre fridge with only 66kWh per year. Or 180Wh per day. Or average 7.5 watts!
I have been keeping eye on efficient fridges and now actually saw first EU2021 A-rated model.
Der preisgünstige und kompetente Onlineshop wermuth.de
Der preisgünstige und kompetente Onlineshop für Ihre Elektrogeräte rund um den Haushalt, Kommunikations- und Unterhaltungselektronik.
www.wermuth.de
330 litre fridge with only 66kWh per year. Or 180Wh per day. Or average 7.5 watts!
Daddy Tanuki
Solar Wizard
New EU energy ratings dropped A++ fridges to C or D rating.
I have been keeping eye on efficient fridges and now actually saw first EU2021 A-rated model.
Der preisgünstige und kompetente Onlineshop wermuth.de
Der preisgünstige und kompetente Onlineshop für Ihre Elektrogeräte rund um den Haushalt, Kommunikations- und Unterhaltungselektronik.
330 litre fridge with only 66kWh per year. Or 180Wh per day. Or average 7.5 watts!
Daddy Tanuki
Solar Wizard
What are they measuring differently? How are their measurements different and how much of that is driven by some company paying them money?
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,522
Grading on a curve?
Trying to goose the economy for the benefit of certain manufacturers?
Power consumption figures, and cost at local rates, would be the most useful grade.
I wouldn't want to pay $500 or $1500 to replace my "D" grade fridge with an "A" grade one if it cut power consumption by $10 or $50/year.
Besides, the new one could be equally low scoring in a couple years.
Like those instant water heaters that are supposed to save me so much power an money. Compared to what, the $8/month bill I see for stove + hot water? And I'm supposed to pay $2000 installed for the "efficient" one? And pay to have it periodically descaled?
Trying to goose the economy for the benefit of certain manufacturers?
Power consumption figures, and cost at local rates, would be the most useful grade.
I wouldn't want to pay $500 or $1500 to replace my "D" grade fridge with an "A" grade one if it cut power consumption by $10 or $50/year.
Besides, the new one could be equally low scoring in a couple years.
Like those instant water heaters that are supposed to save me so much power an money. Compared to what, the $8/month bill I see for stove + hot water? And I'm supposed to pay $2000 installed for the "efficient" one? And pay to have it periodically descaled?
wattmatters
Solar Wizard
Energy efficiency isn't just about money saved in operational energy costs.
It helps to extend the functionality of a given energy supply system (you can do more with less), and/or reduce the scale of the energy supply system needed in the first place (less up front investment required to supply your energy needs).
It helps to extend the functionality of a given energy supply system (you can do more with less), and/or reduce the scale of the energy supply system needed in the first place (less up front investment required to supply your energy needs).
The problem with the previous scale was that everyone was hitting A+, A++ and A+++ ratings now. These now go back to a scale from G to A. To get an A rating, the consumption has to be less (don't remember the exact number, but quite a bit) than the current A+++ devices These current A+++ devices fall in the B and lower categories now. In addition, it adds repair-ability to the set of requirements.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,522
The energy supply can be calculated in $$$, whether from PV, LiFePO4, or gasoline. It makes a convenient "currency" for consideration of efficiency options.
For products and services we buy, the cost gives some indication of labor and energy input, including for shipping.
So I would compare the purchase price of a replacement refrigerator with purchase price of additional PV panels to power the old, inefficient one.
This is how I came to the decisions of over-panel/under-battery, and don't replace my old reliable energy-hog refrigerators. ("Reliability" is harder to put a price on.) I just need to set up a (night time on battery) disconnect for the refrigerators, due to how small my battery is compared to nighttime loads.
MurphyGuy
It just needs a bigger hammer
- Joined
- May 20, 2020
- Messages
- 4,129
That's my attitude as well. Panels are so darn cheap its not worth replacing my refrigerator.. Why spend $3000 on a fridge when I can spend $400 on panels?
wattmatters
Solar Wizard
Of course $3k on a fridge v $400 on panels isn't a difficult choice.
But at some point the marginal costs can jump quite a bit. e.g. when your MPPT(s) is (are) maxed out meaning adding or upgrading the solar charge controller(s), or the power draw is a bit more than the inverter's able to cope with, so you need a newer bigger inverter, or the battery isn't quite getting you through the night or days of poor solar PV, or there is no more roof space and you need to build a ground mount to accommodate that extra "cheap" solar PV, or you actually want to add more fridge capacity, or some other device which adds load.
Maybe there is a $1k fridge that's not quite but nearly as good but uses 50-60% of the energy.
My point is it is worth considering the demand side.
curiouscarbon
Science Penguin
- Joined
- Jun 29, 2020
- Messages
- 3,022
I’ve given up on buying random fancy fridges and just doing a quick thermal analysis of condenser coil location, and then retrofit vacuum insulated panels, neoprene, and a low capacity air blower to facilitate heat removal from condenser.
Even though each vacuum insulated panel costs like 20-50usd, I can at least be certain about what the properties are.
Even though each vacuum insulated panel costs like 20-50usd, I can at least be certain about what the properties are.
Depends on your location though. I want an efficient fridge since I don't have sun in Winter.
That would be my approach as well and I can’t care less how much electricity our home fridge currently uses as we heat the house with electricity anyways.
My interests (RV, campers) and location(Finland) set quite a bit different starting point for calculations.
700kwh vs 66kwh becomes issue if you have limited space for panels, need to survive 2 weeks cloudy spell in summer or live trough winter with gasoline generated electricity at 1.5usd/kWh
66 kWh per year is remarkably little in a way that you could survive trough 3 months total darkness of arctic winter on battery power alone.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,522
True; my AGM bank could (to 85% DoD once per year) do that (based on kWh numbers, if not months at reduced SoC being harmful. And only if I keep the battery warm.)
But we're talking about winter here!
And you're worried about how to keep your milk cold?!
We have A/C & heat pump in one package - is that available for refrigerators?
Maybe you're consuming gasoline (or wood) to keep from freezing. So you have a hot side, a cold side, and you want the refrigerator to be somewhere in the middle. That doesn't necessarily have to consume any kWh at all.
Yes, for an RV very low power consumption would help size PV system.
But there are apparently some issues with having freezers operating in ambient conditions below freezing (or even just cold.) Like they may fail to turn on and keep your food frozen.
A random "best" efficiency appliance might fail to work in your situation.
But we're talking about winter here!
And you're worried about how to keep your milk cold?!
More like worried it gets too cold
Daddy Tanuki
Solar Wizard
just to toss this into the discussion... So I was having transient voltage surges that were triggering my inverters HV disconnect. and this was why: I over paneled this year when I commissioned/installed my lithium bank. I did this as I wanted more power in the gloomy months and or winter to keep the battery cells charged as long as possible prior to loss of solar input.
whats happening is that my solar controllers voltage starts surging when the BMS shuts off charge. I tried to taper my charging using the controllers settings to avoid issues but no dice. so one controller#1 shuts off at 54 volts. the next inline #2 shuts off at 54.2 the next at 54.3 and the last one at 54.4 but when the inverter draws a big enough load they all turn back on. amps/watts surge and after about 5 or 6 minutes the bms shuts down charge, but the inverter is still pulling power so the controllers surge above the 54.4 settings and then one after the other shut off due to high voltage settings. when the last one shuts off it sends a millisecond voltage spike to the inverter which then shuts off due to HVD and after a short time at normal voltage turns back on. cycle repeats several times before the sun goes low enough to prevent this. still trying to figure out how to prevent this. damn first world problems!
whats happening is that my solar controllers voltage starts surging when the BMS shuts off charge. I tried to taper my charging using the controllers settings to avoid issues but no dice. so one controller#1 shuts off at 54 volts. the next inline #2 shuts off at 54.2 the next at 54.3 and the last one at 54.4 but when the inverter draws a big enough load they all turn back on. amps/watts surge and after about 5 or 6 minutes the bms shuts down charge, but the inverter is still pulling power so the controllers surge above the 54.4 settings and then one after the other shut off due to high voltage settings. when the last one shuts off it sends a millisecond voltage spike to the inverter which then shuts off due to HVD and after a short time at normal voltage turns back on. cycle repeats several times before the sun goes low enough to prevent this. still trying to figure out how to prevent this. damn first world problems!
Without knowing your hardware you probably should let the solar charge controllers take care of the battery voltage regulation and set the BMS cutout somewhere above the normal operational range.
Daddy Tanuki
Solar Wizard
sorry put this in the wrong discussion, but to answer honestly... I did that, BMS are set to cut off at 3.65 per cell or 54.4 for the pack inverter is set with a HVD of 64 volts so the issue is that the MPPT SCC get wonky when the battery is disconnected. nothing is harmed, it just cycles the BMS & SCC & inverter both off and on.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 20,522
(Until you put it in a different thread)
Sounds like this issue is when inverter stops drawing current, current from multiple SCC drives voltage on battery above BMS disconnect.
Try with a single SCC, then two, etc.; see if it operates without disconnecting when less total SCC current is applied.
An MPPT SCC has an inductor. It works by closing FET switch between inductor and PV until current reaches some level, then opening switch and letting current continue circulating through a diode until it drops below some level. There is a certain amount of energy stored in the inductor.
When voltage (or current) is below target, it closes switch more to ramp up current. When voltage gets too high it stops doing that, but stored energy in inductor still gets deposited on DC bus, in battery. More SCC connected, more total Wh (or watt-seconds) are shoved into battery.
Maybe added capacitance on DC bus would absorb that energy with less voltage rise, so nothing disconnects. I've determined that no reasonable size capacitor will buffer 60 Hz current draw for a half cycle, but SCC use higher frequency to synthesize DC, and energy stored should be small enough to buffer with more capacitor.
Lithium batteries shoot up in voltage faster when higher up knee of curve. Maybe a lower max voltage setting of SCC will let them accept a pulse of current without rising to BMS disconnect voltage.
Can BMS be told not to disconnect immediately on over-voltage, but wait a couple seconds? Some inverters have such a setting for low-voltage disconnect, because during surge current draw the battery voltage dips due to IR drop rather than SoC.
Sounds like this issue is when inverter stops drawing current, current from multiple SCC drives voltage on battery above BMS disconnect.
Try with a single SCC, then two, etc.; see if it operates without disconnecting when less total SCC current is applied.
An MPPT SCC has an inductor. It works by closing FET switch between inductor and PV until current reaches some level, then opening switch and letting current continue circulating through a diode until it drops below some level. There is a certain amount of energy stored in the inductor.
When voltage (or current) is below target, it closes switch more to ramp up current. When voltage gets too high it stops doing that, but stored energy in inductor still gets deposited on DC bus, in battery. More SCC connected, more total Wh (or watt-seconds) are shoved into battery.
Maybe added capacitance on DC bus would absorb that energy with less voltage rise, so nothing disconnects. I've determined that no reasonable size capacitor will buffer 60 Hz current draw for a half cycle, but SCC use higher frequency to synthesize DC, and energy stored should be small enough to buffer with more capacitor.
Lithium batteries shoot up in voltage faster when higher up knee of curve. Maybe a lower max voltage setting of SCC will let them accept a pulse of current without rising to BMS disconnect voltage.
Can BMS be told not to disconnect immediately on over-voltage, but wait a couple seconds? Some inverters have such a setting for low-voltage disconnect, because during surge current draw the battery voltage dips due to IR drop rather than SoC.
