Here is a real world use case. I have just put a 14.5 Refrigerator/Freezer in my basement at my cabin and it works well, but it is currently powered by an extension cord to an outlet shared by a lot of other loads. Getting a new circuit will cost about $350. Here is an alternative.
Frigidaire customer service says the load is 500w. They will not tell me the cold cranking amps or surge watts. Someone in customer service tells me I run it off of a generator but they don't know the difference between MSW and PSW. From Energy Star the average is 780 Wh / day.
Frigidaire - 500W
Surge - 1000W ? (Guess)
Load - 780 Wh / day
Cost of electricity = 14.496
TOU with baseline of 13.8 Summer, 25.7 Winter gives me 10 hours at 1 cent / kWh
I propose:
2 6v US Batteries US2200XC @ 232AH $99.9 each ($20 core) - published cycles 1150
Samlex SSW-600-12A Inverter for $173
Samlex SEC1230A Smart Charger with DC UPS for #204.
At 50% DOD I calculate the cost of battery power to be 12.48 cents / kWh. I propose to pro-rate the inverter and charger ($173, $204) over ten years. That brings the cost to 14.84 cents / kWh. My current fixed rate at baseline is 14.496.
The batteries at 50% should run the load for 42.8 hours.
Setup:
110v -> Timer -> Samlex DC-UPS -> Battery -> Inverter -> Refrigerator
The timer will supply power to the charger from 10PM to 8AM when power costs 1 cent / kWH. Should take 6 hours. That brings my cost of power to 15.84 cent per kWh. That is a savings of $88 per year based on non-TOU with no load shifting of cheap power.
Another way of looking at it, is that I pay for my inverter and charger with the money I did not spend having a new circuit installed for the refrigerator. Then the cost of electricity is 12.48 cents per kWH + 1 cent for TOU baseline = 13.48 cents / kWh, lower than my current non-TOU baseline of 14.5 cents / kWH.
If I switch to TOU I will also put a timer on my Electric Hot Water Heater to only heat during low TOU baseline rates.
What did I forget? Does this make sense?
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Just got an email from Interstate. Asked about Costo golf cart batteries. They are a more economical version of the XHD with 207 AH and he said they get the same cycles, which are 650 @ 80% DOD and 1220 @ 50% DOD. That brings the cost down to 11.09 cents / kWh @ 50% DOD. So far that is the best I have found.
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Frigidaire customer service says the load is 500w. They will not tell me the cold cranking amps or surge watts. Someone in customer service tells me I run it off of a generator but they don't know the difference between MSW and PSW. From Energy Star the average is 780 Wh / day.
Frigidaire - 500W
Surge - 1000W ? (Guess)
Load - 780 Wh / day
Cost of electricity = 14.496
TOU with baseline of 13.8 Summer, 25.7 Winter gives me 10 hours at 1 cent / kWh
I propose:
2 6v US Batteries US2200XC @ 232AH $99.9 each ($20 core) - published cycles 1150
Samlex SSW-600-12A Inverter for $173
Samlex SEC1230A Smart Charger with DC UPS for #204.
At 50% DOD I calculate the cost of battery power to be 12.48 cents / kWh. I propose to pro-rate the inverter and charger ($173, $204) over ten years. That brings the cost to 14.84 cents / kWh. My current fixed rate at baseline is 14.496.
The batteries at 50% should run the load for 42.8 hours.
Setup:
110v -> Timer -> Samlex DC-UPS -> Battery -> Inverter -> Refrigerator
The timer will supply power to the charger from 10PM to 8AM when power costs 1 cent / kWH. Should take 6 hours. That brings my cost of power to 15.84 cent per kWh. That is a savings of $88 per year based on non-TOU with no load shifting of cheap power.
Another way of looking at it, is that I pay for my inverter and charger with the money I did not spend having a new circuit installed for the refrigerator. Then the cost of electricity is 12.48 cents per kWH + 1 cent for TOU baseline = 13.48 cents / kWh, lower than my current non-TOU baseline of 14.5 cents / kWH.
If I switch to TOU I will also put a timer on my Electric Hot Water Heater to only heat during low TOU baseline rates.
What did I forget? Does this make sense?
###
Just got an email from Interstate. Asked about Costo golf cart batteries. They are a more economical version of the XHD with 207 AH and he said they get the same cycles, which are 650 @ 80% DOD and 1220 @ 50% DOD. That brings the cost down to 11.09 cents / kWh @ 50% DOD. So far that is the best I have found.
###
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