

Wattvision (YC W09): Catching the Power Company's Mistakes - savrajsingh
http://blog.wattvision.com/the-case-of-the-improperly-configured-meter

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jws
A standard household ammeter watches the electrons sashay back and forth in
the wires and totals that up. e.g. you get billed for both current you use and
current you produce (since they never imagined that when they built the
meter).

A "net-metering" ammeter determines if the electrons are cycling back and
forth because you pushed them, or because the power company compelled them and
tallies them appropriately.

Does anyone know how they determine "why" the current moved? At a first crack,
I'd check the voltages very carefully on either side of the ammeter and decide
which was bigger, but this is going to be complicated since there will likely
be different answers across the complete cycle.

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mindslight
All power meters work by measuring both voltage and current and multiplying.
Even without local generation, power periodically (60/50Hz) flows back into
the grid (except when the load is purely resistive aka power factor of 1).

<http://en.wikipedia.org/wiki/Power_factor>

The mechanisms in old meters were just designed with the assumption that the
net flow was always into the house (perhaps in response to the various tricks
people would use to artificially slow their meters). A modern digital meter
doesn't have to do anything special to measure the direction for net metering.

~~~
pmjordan
To elaborate on this: assume the sine waves of voltage difference and current
are fully in phase when the house is net-consuming. Multiplying the voltage
and current functions and integrating over time gives you the total energy
consumption.

When the house is net-producing due to solar panels, the current will be 180°
out of phase with voltage, i.e. "negative" AC current. Multiplying and
integrating yields negative energy consumption.

Note that current is directional, so "negative" current isn't anything special
- if you reverse the meter, the sign will be inverted.

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jacquesm
With these stories Wattvision is doing an excellent job of positioning their
device as 'something that pays for itself'.

Really, keep it up, super marketing! Have you considered a 'the device will
pay for itself within a year or your money back' guarantee?

~~~
savrajsingh
Yes, we could have that -- not sure exactly how we'd quantify it though. ;)

~~~
jacquesm
Gather stats about your users electricity consumption by asking them to
participate in an experiment where they get an anonymous ID, then they enter
their old electric bills and the ones after they bought wattvision.

Next you get to do a lot of datamining and analysis to figure out which
reports are outliers. You'll need a control of people that do not use
wattvision.

Once you've done that you can compare the two and figure out how much of the
drop is attributable to the device and how much to other influences (season
and so on).

That should give you an idea based on the current price per KWh how long on
average it takes to earn back the value of the device.

You'll have to add a safety margin. In order to qualify for a refund people
would have to send you their _actual_ before and after stats for a 12 or 24
month period, so scans or PDFs of their electrical bills.

I'm sure there are lots of details to be worked out but that's the approach
that I would take and before making any public claims you'd have to make sure
the whole process can't be gamed in any way.

No point in becoming another cue-cat ;)

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ShabbyDoo
Thematically, I am excited about technologies/businesses which shift the
balance of power between consumer and large corporation. That the man whose
story was reported in the blog entry implicitly was burdened with the
requirement to prove he was being cheated is a fundamental problem in his
relationship with his "business partner" (a term I chose because each party
sells power to the other). How many other common consumer relationships are
like this?

I am angered that almost all consumer-grade laptop providers drop driver
support only a few months after discontinuing a particular model. There's no
easy way to prove that stability issues which crop up later are the result of
interaction effects between, say, a Windows 7 update and a particular revision
of my video driver. How could someone make HP, etc. accountable? This is
merely one example of how consumers are hurt from information asymmetry.

How does one go about auditing his mobile phone bill and ensuring that it
actually adheres to the stipulations in his plan "contract" (quotes because
there often seems to be no official written statement of terms for a
particular plan)?

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plusbryan
I love these stories. Must feel great to have a real impact on real customers.
Keep it up!

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adnanmahmud
This ia a great way to meter energy usage. Definitely need to get my hands one
of their products.

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gridspy
I'm looking forward to hearing similar stories as we deploy Gridspy. Well
done.

