Battery ?'s

JRHill said:

littleharbor2 said:

I was shocked because I was under the impression it would draw 1100 watts. My new array runs it just fine. I thought I would be able to run my 2000/1600 watt generator with it.  I as it climbs up over 1600 watts it causes my genny to stumble. A friend runs her 1 ton unit off a Honda 2000 genny but she has a different 1 ton unit. Must be more efficient.

1100 watt or close to that max soft start would be wonderful. I still have room for 3 more panels on the roof but those are the last to get full sun in the summer around 10:30am. They are SunTech 195 and I have 3 extras that I can relocate now that the well runs off the house so all I have to but is change the 7 to a 15 breaker and add few 2x1 adapters. No problem with the FM80.

Next year if I find the right minisplit. What brand does your friend have?

SteveK said:

littleharbor2 said:

Well, I was shocked just now. Not with voltage, with the current reading of my minisplit. It is pulling 14.6x amps @115 vac, 1660+ watts

Good thing you got all those PV watts and lots of sun to feed it. This is, I assume, a momentary measurement where the split may have been just ramping up to account for rising outdoor temps and may have settled back lower once it exceeded the setpoint. Not sure but either way was the outdoor temp on the rise and were you cool enough in the home?

I hope so because with 110+F outside and 90+F water temp the only relief left is an underground bunker where you most likely would find that 90+F water again.

Thanks for the comparison.

I used a true rms clamp meter and watched the current rise over about 3 - 4 minutes to the peak I mentioned. I ended up settling down to the 12.xx amp range.
 This is an inverter type unit and it is 110 volts, not 220.

BB. said:

Remember the issue with measuring AC Voltage and Current...

AC Power = Voltage * Current * Power Factor (shape of waveform--Example of current "peaks" vs purse sine wave)
AC power = Voltage * Current * Cosine of the phase angle between Voltage and Current

And there is VA (volt*amps)

VA = Voltage * Current

For transformers, AC inverters, Residential Generators, Wiring, etc.--VA is the Number needed to size the system.More or less, VA=Watts for sizing.

For Commercial systems (and some other specialized systems), there can be an 80% fudge factor--I.e., VA * 0.80 PF = Watts

When working with solar harvest (in Watts) and generator fuel usage (i.e., gallons per hour, etc.), more or less those numbers depend on the Watts (not VA) numbers.

It is relatively easy to measure Voltage and Current separately (Digital Multi-Meter, Current Clamp meter, etc.). If the voltage and current wave forms are "sine wave", "cheap" DMMs can give "accurate" numbers (they "assume" sine waves).

For non-sine voltage and current wave forms, then need "better meters" with True-RMS (root mean square) capability. These meters calculate the proper voltage and current values for arbitrary wave forms.

https://www.fluke.com/en-us/learn/blog/electrical/what-is-true-rms

To measure actual power, then you need a meter than does True-RMS and measures both the wave form, and the phase angle between V and A.

A kill-a-Watt meter can do a "decent job" of giving Watts. 

~15 years ago (2008), somebody compared a Kill-a-Watt ($20 at the time) to a Fluke power meter ($2,000 at the time).

https://forums.anandtech.com/threads/kill-a-watt-power-meter-accuracy.137169/

You get what you pay for... But even lab grade power meters can have their issues too giving accurate/consistent with other meters results..

-Bill