My proposed system can't power my AC

[hodad66]

I was told that my system above couldn't support my air conditioner. If we wire my system
as "whole house" what happens to the AC if we have an outage and it tries to start up? Can
it keep operating if it is sunny, mid day & we get an outage? I had requested a "Sure Start"
within the proposal but they said that it still wouldn't work.

Any input? Thanks

 

[Maximapolak]

How is it that it won't work with 2 power walls? Are they saying you need a bigger system, or more batteries?

 

[nyprepper]

I have the same system... 6.6kw PV, 2 PW's, 7.6kw inverter. interestingly enough, my first year production estimate was 11,000kwh. We have one central AC unit and they installed a Sure Start on it (even though I didn't ask for one). In a recent off grid test, I had the two PW's putting out over 10kw's continuous to the house. I do not know what would happen if the house was drawing more than 12-14kw from the batteries.... I'll try that scenario in my next test. What other big wattage items do you have ?.... heat pump? electric water heater? pool heater? EV charger?

 

[hodad66]

I have the same system... 6.6kw PV, 2 PW's, 7.6kw inverter. interestingly enough, my first year production estimate was 11,000kwh. We have one central AC unit and they installed a Sure Start on it (even though I didn't ask for one). In a recent off grid test, I had the two PW's putting out over 10kw's continuous to the house. I do not know what would happen if the house was drawing more than 12-14kw from the batteries.... I'll try that scenario in my next test. What other big wattage items do you have ?.... heat pump? electric water heater? pool heater? EV charger?

They said that my LRA was too high....... on my 2 ton unit. I have a water heater & L2 charger
but wouldn't try using the charger during an outage.

 

[hodad66]

How is it that it won't work with 2 power walls? Are they saying you need a bigger system, or more batteries?

My advisor blamed it on the LRA and that more of either (PW or PV) wouldn't help.

 

[ewoodrick]

So, you mention that you wouldn't use the charger during an outage. What happens if you were using the charger and the power goes out?
While I'm not sure what would happen to a Powerwall if it is overloaded, my guess is that it would just shut down, along with the entire house.
Also remember, that batteries discharge much faster at full load than partial load.

It takes a LOT of solar and a LOT of batteries to take a Florida house through a power outage. And that's a short outage. For a hurricane, you are really headed toward generators.

 

[MP3Mike]

If we wire my system as "whole house" what happens to the AC if we have an outage and it tries to start up?

If the LRA is really too high I believe that causes an overload and the Powerwalls, and solar, shut off.
​

My advisor blamed it on the LRA and that more of either (PW or PV) wouldn't help.

What is the LRA on your AC unit?

 

[hodad66]

If the LRA is really too high I believe that causes an overload and the Powerwalls, and solar, shut off.
​

What is the LRA on your AC unit?

Listed at 58

 

[hodad66]

So, you mention that you wouldn't use the charger during an outage. What happens if you were using the charger and the power goes out?
While I'm not sure what would happen to a Powerwall if it is overloaded, my guess is that it would just shut down, along with the entire house.
Also remember, that batteries discharge much faster at full load than partial load.

It takes a LOT of solar and a LOT of batteries to take a Florida house through a power outage. And that's a short outage. For a hurricane, you are really headed toward generators.

Yea, for an extended outage I would look for ceiling fans & fridge and maybe some TV......

 

[MP3Mike]

Listed at 58

That doesn't seem like it would be a problem... Though it might require a third Powerwall to be 100% reliable depending on what else is on when the AC starts.

 

[SoundDaTrumpet]

Tesla feeds the LRA value into their proprietary calculation. The typical LRA for 2-ton (Carrier Comfort 13SEER) is 58A. The 30A limit per PW applies directly to non-motor loads, hence the Tesla calc. The Sure Start soft starter was not compatible with my type of compressor. Tesla said I can revisit this when I replace my HVAC system. Right now, with CT installed on the AC circuit, the PWs will peak shave, but during outage only the blower will operate.

 

[hodad66]

If we have a two hour outage I sure would like to keep cool if we could "ramp up"
the start for the AC......

 

[hodad66]

I would like a split system for the bedroom that would work in the case of
a protracted outage (hurricane) to sleep with at night.

 

[Maximapolak]

Window unit AC for hurricanes.

 

[Shygar]

Put a hand crank on your AC condenser to get it spinning .

 

[Dan123]

Listed at 58

That's high.

Your options are:
1. Get a more efficient compressor. I have a 5-ton Trane variable speed with 27 LRA.

2. Get a window/portable AC unit to use in an emergency.

 

[Frankman60]

I have a York 5 ton model YCJF60S41S1 compressor and have two Powerwall 2s. I am trying to determine the maximum number of kWs this until will draw on start up to see if it is going to overload the two PWs. If the kW draw is too high, how do I determine whether it is compatible with a Sure Start soft starter to make it PW friendly?

 

[Dan123]

I have a York 5 ton model YCJF60S41S1 compressor and have two Powerwall 2s. I am trying to determine the maximum number of kWs this until will draw on start up to see if it is going to overload the two PWs. If the kW draw is too high, how do I determine whether it is compatible with a Sure Start soft starter to make it PW friendly?

Your compressor has a label which has numbers on it.

It looks something like this. It has an LRA number, and the maximum circuit ampacity.

 

[Frankman60]

Thanks, got it. The LRA is 135. Does that mean that the compressor can draw up to 135 amps at start up? That seems too high. The specs for the compressor state: Minimum Circuit Ampacity = 35.9, Maximum Overcurent Device Amps = 60, and Minimum Overcurrent Device Amps = 40. I am going to assume that the compressor start up will overload two PWs but will a Sure Start soft starter allow the compressor to work with 2 PWs assuming no more than 2 kWs of concurrent other house load?

Your compressor has a label which has numbers on it.

It looks something like this. It has an LRA number, and the maximum circuit ampacity.

 

[NuShrike]

Thanks, got it. The LRA is 135. Does that mean that the compressor can draw up to 135 amps at start up? That seems too high. The specs for the compressor state: Minimum Circuit Ampacity = 35.9, Maximum Overcurent Device Amps = 60, and Minimum Overcurrent Device Amps = 40. I am going to assume that the compressor start up will overload two PWs but will a Sure Start soft starter allow the compressor to work with 2 PWs assuming no more than 2 kWs of concurrent other house load?

The soft-starter may drop your LRA by 60% or more, so you'll end up being around 54A, which is still a bit tight but doable.

You'll have to first install the soft-starter and then measure your load. I opted to leave my A/C unbacked up until I can just replace it with a more modern and lower LRA system.