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Load planning and research today

pvdude

Solar Enthusiast
Joined
Feb 8, 2021
Messages
619
Location
Florida
I tried an experiment today, very interesting results.
Rather than try to make a list of all the items/watts in the house that are plugged in, I just opened the
Utility/genset transfer switch cover, and put the Fluke AC amp clamp on the utility side 3/0 cables.
Screen Shot 2021-02-12 at 16.17.26.png
The typical house load stays around 16A (3840w).
When the well pump is added, the load goes up to 26A (6240w)

When the HVAC is added (it’s 30c here today!) 36A (8640w)

Seems like we might be able to get more use out of the new solar installation than I originally thought.
The Schneider Electric Conext XW Pro 6848 is rated at 6kw continuous.

When I get the system installed and operational, going to try to see if the entire house can run on it.

I’ll open the breakers for the heavy loads, and just see how it goes with the little stuff operating.
(the Conext has some kind of monitor software, possibly an app of some type I might be able to use, not sure yet)

If it is possible to run the house and manage connecting some of the larger loads on a planned basis, that would be amazing.
 
I tried an experiment today, very interesting results.
Rather than try to make a list of all the items/watts in the house that are plugged in, I just opened the
Utility/genset transfer switch cover, and put the Fluke AC amp clamp on the utility side 3/0 cables.
View attachment 36969
The typical house load stays around 16A (3840w).
When the well pump is added, the load goes up to 26A (6240w)

When the HVAC is added (it’s 30c here today!) 36A (8640w)

Seems like we might be able to get more use out of the new solar installation than I originally thought.
The Schneider Electric Conext XW Pro 6848 is rated at 6kw continuous.

When I get the system installed and operational, going to try to see if the entire house can run on it.

I’ll open the breakers for the heavy loads, and just see how it goes with the little stuff operating.
(the Conext has some kind of monitor software, possibly an app of some type I might be able to use, not sure yet)

If it is possible to run the house and manage connecting some of the larger loads on a planned basis, that would be amazing.
Does the inverter spec provide a KVA rating? Both the well pump and the AC will be inductive loads. The KVA usage will be higher due to the inductive load factor.

If they don't already have them, you will want to put compensating capacitors on the pump and AC to try to get the power factor as close to 1 as possible.
 
All I could find in the manual:
“High-capacity motor load starting with high 30-minute and 5-second power.”

It says overload is 8500watts for 30 minutes, 12000 watts for 30 seconds.

I already put s “soft-start” circuit (capacitor & relay) on the heat pump, because when we are running on generator, and the heat pump scroll compressor contactor closed to start it, the generator tried to launch into orbit. All fixed now.

Also found this, says power factor is .95:
Screen Shot 2021-02-12 at 17.23.28.png
 
Also found this, says power factor is .95:
Is that in the inverter manual?

If so, it looks like you might be able to compensate some by adjusting that setting. However, it really needs to be fixed at the load.
already put s “soft-start” circuit (capacitor & relay) on the heat pump, because when we are running on generator, and the heat pump scroll compressor contactor closed to start it, the generator tried to launch into orbit. All fixed now.

The soft-start only helps during start. It needs a run capacitor to compensate during run time.
 
I have a Schneider XW+ also, and the biggest one day load I've measured was about 3600W. It seemed to handle that load just fine, but I would be very cautious about pushing any electronics close to their upper limits every day. It powers my well-pump, which has a 9000W+ starting surge, but running is only consuming about 2000W.

I am really comfortable at running most equipment at about 1/2 capacity, and I'd include the XW in that category too. If you really want to be running 6200W for a good portion of the day, I'd suggest looking at two XW's in parallel. That would give you 12kW available, which a 6200W load would be about .5X
 
Looks like when you're running on-grid, the XW can observe non 1.0 PF going out to the grid due to pump motor, and can provide active power factor correction. Not that you care, and only if pump is on protected-load side of inverter.
When you're running off-grid, all it can do is supply whatever the pump demands, and absorb power returned out of phase due to PF.

Was that 2500W more when pump ran, and an additional 2500W when A/C ran together with pump? Or was the A/C 5000W on its own?
Whatever the motor drew, expect 5x that as starting surge.
Capacitor for PF correction might help efficiency a bit. One of those soft-start gizmos is the only thing that may help if inverter can't start the motor.
 
I agree about reducing the load to the minimum, would not run anywhere near 6kw, except for short peaks.
I'll turn off/disconnect devices in the house until the db level from the wife complaining reaches equilibrium.

How much heat does the XW+ put out?
I am installing the XW pro 6848 inverter/charger and the Conext MPPT 80 Charge Controller in a small, unoccupied building.
(workshop behind the house)
No AC, so it gets hot in there.
I have searched the documentation, no mention of the BTU load these devices put on their environment.
Because they both have fans, it seems likely there is some amount of heat being produced.

The 3840 watts is normal house loads.
Goes up to 6240 watts with the well pump running.
(pump takes about 30 seconds to fill the precharged pressure tank)
Load increases to 8640 watts with heat pump running at the same time the well pump is running.

I am pretty sure the 12kw overload capacity of the Inverter will start the well pump fine, as the genset does not grunt to start the well motor.
Have doubts about the inverter starting the heat pump.
 
Charge controller is quite efficient. Maybe 2% of power turned to heat.
Inverter more like 10%, check the manual. So at 4000W load it is a 400W heater.

Well pump is 2500W running, likely 12,500W starting surge for 0.2 seconds.
Heat pump is 2500W running, likely 12,500W starting surge for 0.2 seconds.

You might be able to set up a control that turns off loads (heatpump, especially) below some state of charge, save remaining battery power for lights and refrigerator.
You might wire a signal from water system pressure switch to interrupt heatpump, if inverter can't power both at once. So long as heatpump has a delay before it turns back on (compressors need to have pressure relieved before starting again.)

3840W "normal" house load would be 92 kWh/day if round the clock. That is excessive when heat/air conditioning not included. Review/reduce that figure.
 
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