Kill-A-Watt or Seasonic PowerAngel will measure power and energy
usage (PF, voltage, current, frequency, and anything else they could
think of ;). The Kill-A-Watt says it'll calculate and forecast
"cost". Either will do any measurements you need. You can get the
cost from there with a little arithmetic.
I paid $30 for the PowerAngel at NewEgg but I see Kill-A-Watts for
less than $25 on Amazon.
Don't those devices make spot measurements? The nice thing about the La
Crosse was that it not only calculated the spot cost of energy, but
accumulated data over time and took average readings. So you could set it
to the cost per month, and periodically walk by and see the cost was $23 /
month, for example.
I need to install about 20 of these, and I wouldn't really look forward to
walking around and doing lots of spot measurements and then making my own
calculations. If you have multiple computers attached to one monitor, and
each of those has idle and loaded energy utilizations, it becomes nearly
impossible to correctly calculate the cost of energy consumption as more
than a possible range, since you don't know what percentage of time the
computer is in idle versus loaded states.
The PowerAngel measures kWh and Hours and I think the Kill-A-Watt is
the same (never used one). You'd have to divide to get the average
Since they do measure kWh (and h), it doesn't sound too hard to
figure out the real power usage. Peaks would be pretty simple to
measure also, to get a maximum (all computers going full tilt).
Keepitn track of twenty devices sounds like a lot of work anyway. A
spread sheet would make quick work of any calculations you need.
The Kill A Watt collects and accumulates data as well as tracks time
for as long as the unit is plugged in. Just make sure you get the KW
used and the elapsed time before unplugging it, there is no memory
retention. Works very well for something that only costs $25.00.
A quick web search turns up all sorts of power meters. Here is one
that records and has a USB interface (sounds like you could use it)
I had inquired about something like this a while back.. I have sub-let some
rooms and would like to know the actual power usage of each unit to charge
accordingly. It was suggested that I buy some second-hand refurbished meters
but I thought they were a bit too bulky. Would the total home energy
monitor kit do this effectively?
The problem with the power meter market is that it is really focused on
commercial multi-tenant billing solutions, and the meters are just
expensive, typically $400 to $900 each if you want something that you can
link to a computer by RS-485 or ethernet. Typically such installations are
done one meter per circuit, so if your tenants are each on different
circuits, now you are looking at multiple meters. It's hard to get a
payback on the investment.
The best commercial solution I found was from Satec, and they have an
ingenious product lets you put multiple current readers around specific
circuits, and feed the measurements all to a single device that reads up to
about nine circuits. This collector is then uplinked by RS-485 to
ethernet, and to software on your PC. It's under $1K, and at least it's
flexible to reorganize the groups of circuits you bill for, and consolidates
data collection to one place. The software doesn't look beautiful to be
sure, but I don't find many competitors either.
The open part of the market is the consumer who wants to measure and manage
energy utilization on 10 circuits in order to cut a $500 monthly bill to
$400. It's hard to justify spending $400 * 10 in dedicated monitors on
your fuse panel. It's barely acceptable to spend $1K for the Satec
solution. What would make a lot more sense to me would be some kind of
meter like the Kill-a-watt that has a wireless uplink to a central computer.
But price point for that thing would need to be around $100 / meter,
otherwise you don't pay back the investment fast enough to make it worth
doing out of pocket. I wasn't able to find this product. Everything I
could find was $400+ per meter.
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.