Single Appliance Peak Shifting.

[Russellwalsh2003@yahoo]

Looking at putting an automatic system to shift two major appliances to local battery during peak hours, which are 4:00 to 9:00 PM, and back to grid AC off-peak,
My understanding is this would be something like an A/B switch with A being grid AC and B being the battery plus a properly rated small inverter.
This would be run by a timer. Is there a gadget for this already built that can be used with my already purchased batteries and inverters?

Please send me to the appropriate threads if this has already been covered, Thanks.

 

[BentleyJ]

Major Appliances would imply a fairly large load like an air conditioner, range or water heater. Something like a 6kW to 10kW inverter probably. Most any inverters of this size would have built in timers and transfer relays to automatically perform peak load shave, no need for an A/B switch.

 

[Russellwalsh2003@yahoo]

Major Appliances would imply a fairly large load like an air conditioner, range or water heater. Something like a 6kW to 10kW inverter probably. Most any inverters of this size would have built in timers and transfer relays to automatically perform peak load shave, no need for an A/B switch.

Maybe these are not major appliances then, a side-by-side fridge in the house and a manual defrost chest freezer in an unconditioned space. Either could be run off a 1000-watt inverter I believe. 1000 W is probably not big enough for both. Air conditioning is a higher-demand unit to consider for sure. We have that but rarely use it.
.

 

[hwy17]

If you want to try to do this with low cost small components use a charger > battery > inverter > appliance and then put the charger on a timer so that it is off during the peak hours.

I would look at Morningstar Suresign or Victron Phoenix for the small inverters.

It will probably never pay off the cost of the battery, unless you have like a $.30 peak off peak rate differential.

 

[Russellwalsh2003@yahoo]

I found a timer that can break and make the grid-tied appliance ckt with an automatic switch at the start and stop of a peak, for about $100 for both, my battery and inverter. The battery charger could be put on a $10 timer for off-peak charging. Not sure about the durability of this stuff or if all the bugs can be considered worked out yet.

 

[Russellwalsh2003@yahoo]

If you want to try to do this with low cost small components use a charger > battery > inverter > appliance and then put the charger on a timer so that it is off during the peak hours.

I would look at Morningstar Suresign or Victron Phoenix for the small inverters.

It will probably never pay off the cost of the battery, unless you have like a $.30 peak off peak rate differential.

I have trolling motor batteries sitting around except for two or so fishing trips a month. Plus, geeking out on anything has its costs. Our peak is expensive not sure of the actual differential but will look at that too. Thank you.

 

[BentleyJ]

Peak Load Shaving (shifting) doesn't really make much sense for only a refrigerator and freezer since they are relatively low consumers. Its really not worth the effort and equipment expense.
If instead you wanted to have those items on a back up system so they stay on in an outage that would be more reasonable.

 

[hwy17]

I found a timer that can break and make the grid-tied appliance ckt with an automatic switch at the start and stop of a peak, for about $100 for both, my battery and inverter. The battery charger could be put on a $10 timer for off-peak charging. Not sure about the durability of this stuff or if all the bugs can be considered worked out yet.

You don't need a double timer setup. Look at my comment again and think it through, all you have to do is time the charger and have the appliance always run off the battery. It will result in some double conversion loss though.

 

[Russellwalsh2003@yahoo]

 

[Russellwalsh2003@yahoo]

You don't need a double timer setup. Look at my comment again and think it through, all you have to do is time the charger and have the appliance always run off the battery. It will result in some double conversion loss though.

Got it thanks. Putting all usage through the battery, rather than a few hours a day. Are there pros and cons of that beyond conversion loss? Lithium Phosphate battery.....is that harder on the battery?

 

[hwy17]

Got it thanks. Putting all usage through the battery, rather than a few hours a day. Are there pros and cons of that beyond conversion loss? Lithium Phosphate battery.....is that harder on the battery?

Ripple currents, yes. It could be, not really enough data to say. A lot of us say use the batteries if you got them cause they will die of old age not overuse.

 

[Russellwalsh2003@yahoo]

O.k. I won't worry about the battery.

So, am I looking at this correctly? The system would have 5 hours of conversion losses using the battery only for peak hours of 4:00 to 9:00 pm and 24 hours of conversion losses going through the battery full time? Excess 19 hours of conversion losses at about 30% towards offset advantages of peak shifting cost benefit.

 

[hwy17]

Yes. 19 more hours of conversion losses. Otherwise the solution gets more complicated and expensive with power source switching.