Do you turn off your Enphase microinverters at night?

WebPower

Just curious, does anyone else turn off their grid tie microinverters at night? They consume about 50mA in standby so I calculated the 28 I have would consume a fair amount of power over the course of a year:

0,05A x 246VAC is 12.3w

28 microinverters is 344 W/hour

7 hours darkness is 2408W hours per day

$0.11/KWh is $0.26/day of power used in standby.

364x$0.26/day is $96.00 per year for all 28 microinverters in standby.

The three timers pay for themselves in about a year and a half at $50 each.

Are my calculations right?

I use mechanical timers right now. Tried some digital Sylvania ones but they crapped out. I've got one cloud based that I just installed and will see what that does in the long term.

Comments anyone? Here's a representative picture.

Pat

Photowhit

...and I think the 5ma is max.

BB.

I think Photwhit is closer to actual night-time AC loading. For the IQ7:

https://sunwatts.com/content/manual/Enphase-IQ7-7plus-7X-Micro-Manual-install-guide-EN-US.pdf (page 31):

• Night tare loss mW 50

In current:

• 0.050 Watts / 240 VAC = 0.0002 Amperes (0.2 mAmperes)
• 28 inverters * 0.050 Watts = 1.4 Watts total

Your clock motor, per switch, 2x probably draws around 3 Watts (6 Watts total):

https://www.homedepot.com/p/TORK-120-Volt-60-Hz-Replacement-Motor-101/303973883

Or 4x the Enphase night time power draw(?). And that is 24 hours per day for the timers.

I used to use these types of timers for security lights--But they ended up being a pain in the behind. Between having to reset for the seasons (hours of night by season) and the occasional power failure that had lights on during the day and off at night until somebody noticed and reset the timers.

If I had the chance, I would usually replace with photocell based controller. Dark=Lights on--No timing to worry about.

-Bill

Ralph Day

Really?  My bi-directional meter has accumulated 199 kwhrs on the consumption side since June 2010.  I don't think it's worth worrying about.  If you forgot to turn it back on, for one day, you'd lose more power than several years worth of  overnight consumption.

Ralph Day

And that's for 52 inverters.  The first 140 kwhrs were in the first 2 years.  I upgraded the 100foot feed to the meter from #6wire to 00.  Considerable difference in use and consumption.  (Feed in tariff, all feed, all power to the grid)

WebPower

You guys are trying to burst my bubble! Ha Ha... Now I'm just going to have to go back and measure the actual aren't I? Going from memory from 2+ years ago is probably getting me in trouble here. I'll measure the actual in the next day or so...

BB.

There can be more complexity to the answer too...

I have seen small/standby power supplies (TVs, radios, etc.) that draw a bit of power when "off" (standby). And there is an issue with the "power equation":

• Simple power equation: Power = Voltage * Current
• Actual power equations: Power = Voltage * Current * Cosine between Voltage and current
• Actual power equation: Power = Voltage * Current * Power Factor (cosine and non-linear current wave form)

When using a Kill-a-Watt meter (cheap, probably not that accurate)--I have seen varying power PF numbers with standby loads. And to measure PF, you need a "power meter" and not just a simple current measurement--And the meter needs to do RMS (root mean square) current (and voltage) measurements (RMS = a "mathematical" average of a non-sine wave current profile that gives accurate current readings--Non-sinusoidal components).

https://en.wikipedia.org/wiki/Power_factor

"Good PF" is usually 0.95 to 1.00 Power Factor. "Poor" PF is 0.80 to 0.50 (or less). Meaning that a PF of 0.50 will give you 1/2 of the expected power measurements:

• VA (Volt Amps) = Voltage * Current
• Watts (power) = Voltage * Current * PF

-Bill