Hello Wrenches,
I'm comparing two inverters for a small residential job, where the
inverters will AC couple with a pair of Outbacks during power
outages. The two candidates, so far are the transformerless Power
One and the Kaco, neither of which I have used before.
My questions are:
* Ho
Wrenches,
I recently installed three "ultra -efficient" step up-down
transformers on an off grid micro grid project with a 1500' wire run. The
grid is powered by a an old SW4024(120v) output, stepped up to 480v, and
stepped down to 240v at two locations. I was told by the manufactu
Lars,
Scary stuff. I worked with a system similar to this and went with big wire.
The problem with xfrms is that you can either have low standby losses and
good efficency at load or vis-a-versa, but you can't really have both.
Were the xfrms specifically wound for 120x480 conversion? If not,
Measuring current without the phase relationship between the current and voltage
isn't indicative of the actual power consumed. Likely what you were seeing is
the
eddy current in the transformer core. If so, it's 90 degrees out of phase with
the
voltage, and the real wattage consumed with no lo
The wire would be a one-time-cost. Even "ultra-efficient" transformers
cheat you out of energy for the long-haul, and are an added potential
point of failure.
We are running into customers that have 480V service with 480->120/208
transformers and they want Enphase microinverters. I cringe a lit
I thought (based a previous thread) that we needed to be concerned with VA
output of inverters, not wattage, at least on the transformer based machines
like the SW.
I realize this wouldn't be an actual load if on grid.
In these situations, I just measure DC amps into the inverter to determine the
Focusing on VA ratings would not be advisable.
Here's why.
Watts are real power. This would be actual DC volts
times actual DC amps. Measuring DC volts and DC amps
as you're presently doing is a good approach. It
yields a valid result.
On the other hand, volt-amps ("VA") are nothing more
than
Hi Dan;
I agree that a 2000 VA inverter isn't equal to a 2000 watt unit.
The focus on VA here though was not about looking at the rating of the
inverter, but instead noting that a load with a high reactive component might
draw more energy than a purely resistive load in a battery based inverter
Fellow Wrenches:
Working on a residential PV design using Structural Insulated Panels, or
SIP panels. Preliminary design is three AC strings of 17 microinverters,
in three portrait rows ~18" apart.
The good news is that the builder wants to include the PV as part of the
original construction
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