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You really should get a whole house monitor and get ready for an eye opener on how much power draw all those little " trivial " devices can have. Believe me, they do add up quickly. Also great for showing your significant other why you don't set the thermostat to 75+ in the Winter. My heater pulls 11Kw when running :|

The one I use is called TED ( The Energy Detective ). It's not the current generation model, but it gets the job done. The newer one is more accurate and has a few bells and whistles I don't have. Go read about it here I'm not sure if they make them for overseas customers ( it's US based ) or if you all have similar products available to you.

Once the thing is up and running, the first thought you have is what the hell is drawing all this power ? You then wander around the house turning various things on and off to see what the power draw actually is. My entire entertainment center is now on a power strip that I can kill with a single switch. ( Except for the damn cable box, rebooting those means a 10-15 minute wait while it goes through it's boot process :| )

In the end, I was able to get the power draw down to ~250-280 watts when we're not at home. Some things I simply cannot shut off. ( Bird cage lights, aquarium lights and pumps, alarm, etc. ) The fridge is the only thing that really cycles on / off as we have the hot water heater on a timer of its own.

Very useful little gadget imo.

What resources did you use to model these inputs? PVWatts I can understand for solar, but I'm not aware of any similar tools for wind and micro-hydro. Genuinely interested in what your data sources were.

Not that I'm yet convinced your model is applicable to a regional or national scale grid. Did you account for geographical diversity? Availability of these resources spread out over maybe 200-300 mile radius?

Also, peak demand of 5kW for 3 hours? My home has all electric appliances and I rarely, if ever, hit that... including the 3kW clothes dryer. This observation is neither here nor there, but that just strikes me as a high value.

To put things into perspective, I've been collecting minute-by-minute data for my own home's electrical usage (Got one of these things) and based on incomplete-at-the-time data it was looking like I could get away completely off-grid with a 6-7kW PV system and about 6kWH of storage. Less if I was smarter about how and when I used that power. Maybe your data doesn't have good enough resolution to really optimize the system.
=Smidge=

A kill-a-watt is nice (I got myself one) but it's only good for things you can plug in through it that draw 15A or less.

If you're really serious about finding out where all your power goes, and how much you're using and when, I can suggest a somewhat more expensive Energy Detective system that installs in your main electric panel.
=Smidge=

This app and other rely on a hardware meter such as the TED-5000 (hopefully no relation to the HAL-9000 which can also monitor nascent human rebellions).

Has anybody using one of these found a discrepancy with their utility's "smart-meter" reported energy usage?

Use TED hardware, about $199-$235 these days. Still pricey. http://www.theenergydetective.com/store/ted-5000
Activate with Google PowerMeter for decent charting. It charts 10-minute kW and daily/monthly kWh.

Or, use the TED API yourself to grab power readings (this is a good feature - other similar products don't seem to have.) Chart locally, or send data to a site online, (much like PowerMeter.) Here is some source code to grab power readings and send to custom AppEngine.
http://code.google.com/p/watchmyted/
http://code.google.com/p/myenergyuse/

I use TED. It's right around your price range. It monitors whole-house power usage in real time and has a USB-Serial interface which you can easily suck data out of with Python script. I personally do all the data logging on a Linux box and export it through a web interface.

... I bought one of these, and based on watching my loads over time, 2 kilowatts is no big deal at all. My dryer uses way more power than that. In fact, an electric toaster uses over a kilowatt. So not only could you charge an electric SUV, you could charge an electric freaking train and still have enough capacity to spare.

Not really a direct answer to your question, but I use TED-5000 from http://www.theenergydetective.com/index.html. So far I found a rather precise correlation between data from it and bills from electric company.

Sorry, but this service does not justify that kind of paranoia. Most devices you can use with it are not devices that control power flow; they merely measure it.

Smart power meters like Google is targeting are just that--METERS. For example the TED5000 uses non-invasive current probes that clip onto your power wires and inductively measure the current that is flowing. It then uploads the current data to Google Power Meter where it keeps a trend log you can view from anywhere, which is a legitimate service. The TED5000 itself keeps an internal log, but is not as detailed. It is physically impossible for the TED5000 to interrupt or otherwise impede the flow of electricity into your home--such a device would be large and expensive.

Smart appliances, on the other hand, are IP-enabled refrigerators, air conditioners, etc, that read information from the smart meter and make operating decisions based on it. Google probably wants to encourage smart appliances too, but this app only has to deal with the smart meters at the moment.

So using Google Power Meter with a non-invasive smart meter does not make you vulnerable to control by hackers. The only way you could have a device to shut power off remotely would if it were installed by the utility company or else be a smart appliance you installed yourself.

Sorry to reply to my own comment, but I saw this in another comment on this article: http://www.theenergydetective.com/what/install.html

Much less involved than replacing the utility meter! The TED500 has been added to my shopping list & is compatible w/ Google Power.

Google already partnered with some utilities, and a few device makers (about 7 months ago). Most utilities are slow to provide opt-in to their customers. But anyone can install and watch their whole house power and consumption.

For example, the TED installs at your house main. It happens to send data to Google PowerMeter in the cloud (an App Engine application it seems.)

Right now, it is only one-way. Simply provides monitoring. Nothing can be controlled. You see your 10-minute average power in an iGoogle Gadget. As well as weekly and monthly total consumption, with a couple basic comparisons. In fact, the TED had an API, so anyone can read the second-by-second power readings and build your own charting application, or load a spreadsheet, or use the built-in browser to see gauges of power, etc. So, to make it easier for device manufactures to provide usage data (probably not just electric, but gas and water as well), why not a chip that can be embedded into your device designs.

For those who have not seen Google PowerMeter, tinypic sample here.

I really hope I'm able to access the data from it. If I can get variable pricing based on peak load in the system, then I have a lot of incentive to time my dish washer, clothes washer, etc to do their work in the non-peak times. It saves me money and makes a more efficient load on the system. Everyone wins. Hopefully they don't screw it up.

http://www.theenergydetective.com/store/teds/ted1000.html

You can get this for not much money.

the kill-a-watt only measures what's plugged into it. no, more like this

T.E.D will measure the whole-house usage at the mains.

Not all meters have the spinning dial. I have one on the main house that is pure digital and nothing spins at all. On the rental I live in, I have the dial.

Perhaps something like this http://www.energymonitor.com/ or this http://www.theenergydetective.com/index.html would represent usage accurately enough to accomplish the same things as the poster wants without the hassle of building something of from scratch.

This along with the Computer Interface will be much more reliable. It is sophisticated enough to learn what appliances turn on and for how long and breaks down the usage detail for each.

This does require opening your breaker box and installing a loop around the incoming hot lines. This can kill you if you do not know what you are doing. If you are not familiar with working in hot boxes I recommend having an electrician install it.

My utility provides a box with a smart card that shows real time power usage, balance left on the card and approximate minutes until disconnect. Check with your utility for something similar. I like it much more than the monthly bill.

This along with the Computer Interface will be much more reliable. It is sophisticated enough to learn what appliances turn on and for how long and breaks down the usage detail for each.

This does require opening your breaker box and installing a loop around the incoming hot lines. This can kill you if you do not know what you are doing. If you are not familiar with working in hot boxes I recommend having an electrician install it.

My utility provides a box with a smart card that shows real time power usage, balance left on the card and approximate minutes until disconnect. Check with your utility for something similar. I like it much more than the monthly bill.

The kill-a-watt (mentioned in other replies) is great, but if you have enough toys that they require more than one electrical outlet, as any self respecting geek does, you should get a whole-house monitor like mine. I have one and love it. It doesn't save you energy, but it's a better way to measure consumption than timing your meter revolutions. Now if only I could transfer that data to my computer.

http://www.theenergydetective.com/

Kill-A-Watt monitors electric usage for 1 device or one powerstrip. $30 http://www.thinkgeek.com/gadgets/electronic/7657/

The Energy Detective (TED) monitors the entire house. $140 http://www.theenergydetective.com/

I have both of the above. I use Kill-A-Watt for easy analysis of a device and TED for monitoring the turning on/off of major appliances. I also switch the wiring of TED to my generator to monitor it and make sure I don't go over desired load.

Watt's Up Pro is like Kill-A-Watt is for 1 device or one powerstrip but has additional features similar to TED. $120 http://www.thinkgeek.com/gadgets/electronic/7acf/