# Forum Home Renovation Solar Electrical Systems  Monitoring Electricity Use

## Bill108

I'm considering getting solar, but only if the $$$ make sense. Going to solar will mean my metering will change to the new time of day metering, so I'm keenly interested in knowing how much electricity I use on average for every hour. 
I think the easiest way to do this would be to get a mains based monitor and hook it into my PC. Something along the lines of - Current Cost EnviR « Steplight: sustainability programs and education And then use something like this - http://www.techtoniq.com/shop/ to make sense of the stats. 
In essence, what I want to be able to do is know that on average for any particular hour for any particular day I'm using x KWh.
This will help me determine if the projected savings from solar will cover the rather large tariff increase by moving to time of day metering. 
Has any one else done this? 
Recommendations on hardware / software? 
Anything to look out for or consider?

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## SilentButDeadly

I wouldn't bother if its to figure out whether GC solar is good for you.  Look at your total use and potential capacity to produce solar power. 
How much power do you use in an average day? How much power could your roof area be reasonably expected to produce? Can you afford to maximise the system to take advantage of roof area? 
We use about 8 to 12 Kwh per day and our 2.2 Kwh system takes up all of the 11.5 sqm section of available roof with adequate year round solar access....and produces between 12 and 14 Kwh of power per day at this time of year.  Cost without rebates but after RECS was $7.2K. 
If your roof & wallet can't produce enough power to cover your total power consumption.....then spend the money on reducing consumption rather producing more.

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## lazydays

In QLD we get one of these Clipsal CENT-A-METER Energy Monitoring Device [CM113-CMR113] : Solar power : - Energy Matters Australia http://www.energymatters.com.au/imag...3%20manual.pdf
For $50 we get an electrician out
Change all lightglobes to Energy Efficient ones (put your old incandescent ones back in before they come)
They go through all household appliances and draw up an efficiency plan
Monitor the plan with regular email back -ups and surveys.
Install one of the above devices which is wireless and you are free to take it from house to house. (It even tells the time and temp)
Change your showerhead to a higher rating
4 standby eliminators
ALL FOR $50............Anna Can do  ClimateSmart Home Service | What you get

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## Bill108

> I wouldn't bother if its to figure out whether GC solar is good for you. Look at your total use and potential capacity to produce solar power.

  There is no point in makinging the switch to solar power if its going to cost me more than it saves. 
Looking at my total use in isolation hinders more than helps as I will be paying different rates for different time of use.   

> If your roof & wallet can't produce enough power to cover your total power consumption.....then spend the money on reducing consumption rather producing more.

  I know my average consumption. I also know the average generation capacities of various sized systems in when installed in this area. 
I can get something that will generate more than my average consumption, however the issue is that net power is sold into the network at 8c per KWh, but my main usage time is after dark when I will be generating nothing.  

> In QLD we get one of these Clipsal CENT-A-METER Energy Monitoring Device [CM113-CMR113] : Solar power : - Energy Matters Australia http://www.energymatters.com.au/imag...113 manual.pdf
> For $50 we get an electrician out
> Change all lightglobes to Energy Efficient ones (put your old incandescent ones back in before they come)
> They go through all household appliances and draw up an efficiency plan
> Monitor the plan with regular email back -ups and surveys.
> Install one of the above devices which is wireless and you are free to take it from house to house. (It even tells the time and temp)
> Change your showerhead to a higher rating
> 4 standby eliminators
> ALL FOR $50............Anna Can do  ClimateSmart Home Service | What you get

  That looks like it would do the job.
Pity I'm not in QLD, its a nice price  :Smilie:

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## SilentButDeadly

I still think you are over thinking it....you'll have net metering Bad advice from solar companies in NSW: clarification on what Net Metering means | Solar Questions and http://solarquestions.com.au/wp-cont...explained1.pdf 
So all you'd really need to do is read your meter in the morning (say 8am) and evening (say 6pm) every day for a couple of weeks....

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## chrisp

> I still think you are over thinking it....you'll have net metering Bad advice from solar companies in NSW: clarification on what Net Metering means | Solar Questions and http://solarquestions.com.au/wp-cont...explained1.pdf

  Isn't it amazing that a document issued to clear up the confusion can't get the units right!  Have a look at the *power usage* graphs on page 4 - they use "kW hours used".  kWh is a unit of energy, not power.  The correct unit is kW so the y-axis should be labelled  "kW used".

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## SilentButDeadly

> Isn't it amazing that a document issued to clear up the confusion can't get the units right!

  Sadly....it isn't that amazing.  I suspect that the correct y-axis labelling should have been 'total kW used per hour'.  The real question is would it have been any less confusing?  :Biggrin:

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## chrisp

> I suspect that the correct y-axis labelling should have been 'total kW used per hour'.  The real question is would it have been any less confusing?

  Nah, that expands to "total kilojoules per second used per hour".  That's acceleration of energy! (i.e. mathematically it is a derivative rather than integral) 
 The confusion comes from using cumbersome units with have a time unit in the numerator to cancel out the time unit in the denominator. 
eg Joule is a unit of energy.  Watt is a unit of power = 1 Joule per second (i.e. power is a rate of energy). 
We talk of power in kilowatts (kW) and energy in kW.h.  kW.h is a product: power multiplied by duration 
Expanding kW.h = (kilojoule / second) x hour.  The times cancel to leave a (scaled) unit of energy (i.e. kWh = kilojoule x 3600 seconds / 1 second or 3.6 MJ). 
Clear as mud.  :Smilie:

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## Bloss

Guys - get off the argument on kW vs kWh vs kilojoules - just not relevant for a home owner. You buy your electricity at a kWh rate and you will be selling it at that rate. The electricity retailer doesn't know or care what you call it - energy, power, watt, work - it just doesn't matter. What matters is what you pay for and what you get paid. 
If the utility are putting you onto time of use charging then they should be putting you on a time of production payment for your power - else the utility is making a windfall profit from any power you produce. Utilities mostly charge out at flat rates, but buy at a spot rate in 30min increments (that's  simplification I know, but it's close enough). 
They like time of use charging because that allows them to closer match the price the charge you with the demand price on the spot market. It allows you to decide, for example, not switch on your A/C or use another electricity hog between 5.30pm and 8.30pm as that will save you heaps (but you might be a bit hotter or have to use a fan etc!). 
If they pay you a variable time of production rate then you would orient panels the west north west at the angle of your latitude (Bathurst =33 degrees) to maximise the value of your revenue for power generated. If you are getting a flat rate for your power then you orient as close to due north to maximise the total kWhs you produce each year as that would give you the greatest total volume. 
But you can save more than enough to help pay off a PV system by a few common sense actions which will make almost no difference to your lifestyle - often none at all. Every utility will have a web page or three telling you what they are! But clearly electricity is still cheap - or else many more people would be acting to reduce their use of it.  :Redface:

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