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Solar inverter smart meters

A 'smart meter' or energy meter is probably the most useful and valuable 'optional' component you can buy for your solar installation.


Let's be clear. We are NOT talking about your Synergy/Western Power meter, which is also often called a 'smart meter'.


Inverter smart meters looks like this (Huawei single and three phase to the left, Fronius three phase to the right). About 60% of all current inverters have optional smart meters.


Smart meters are installed in your switchboard


A "comms" data cable is run back to the solar inverter
CT clamps (below) are installed around the main input cable(s)



Installation usually costs $170 to $250.
Single phase smart meters with 1 CT cost $150 to $200.
Three phase smart meters with 3 CTs cost $250 to $450.


Now... what does it DO?


When I write "it shows" in the examples below, what I mean is that the reporting software, smartphone app, web browser, shows the information, usually as an easy to understand graph.


It's hot , so you turn on your airconditioning.
It shows how much power the AC is using.


The pool pump starts up.
It shows how much power the pool pump is using.


Cooking the evening meal?
It shows what the electric oven is using.


It shows ALL the power you are using in your home, 24 hours a day (usually)
It shows the power you are buying from Synergy.

It shows all the solar power you are using in your home.
It shows all the solar power you are storing in your battery (if you have one).

It shows all the solar power you are exporting back to Synergy for a credit.


With a smart meter installed you will soon know how long your home aircon takes to reach the thermostat temperature, and how much electricity it used getting there. Then it will show you how much power your AC uses when the temperature has been reached and it drops down to fan only. (See pictures below)


Ditto your hot tub, your pool pump, oven, bore, tumble dryer, washing machine, dishwasher and any high current draw devices you use. You will also see what your 'base load' is. This is the power a house uses through the night and most of the day when the high current draw devices are off. For most houses that's just running fridges, freezers, lights, computers and is typically about 0.5kW per hour. Even so, 0.5kWh for 24 hours means 12kWh per day just keeping the house running.


If you don't install a smart meter then you only know three things.

You will know how much power your solar produces hour by hour, day to day, and every two months you will know how much electricity, in total, you bought from Synergy, and how much solar power, in total, you exported back to them for a credit. That's it. If you are prepared to do some maths, then you can also work out how much of your solar you consumed by taking the total production for those two months of each Synergy bill, deducting the credits Synergy paid you, and the difference is what your house used. Clumsy, but it does give you an idea.


Another huge advantage of a smart meter is all about battery storage.

For a start, you HAVE to have a smart meter installed when you connect a battery to your inverter, otherwise the inverter won't know when to store or release battery power. The second thing is that, before you buy a battery you can see all your data and work out (or we can do it for you), exactly how much battery storage will be right for you. You certainly don't want to buy too much battery storage because they are very expensive.


Export limiting - that's when you HAVE to install a smart meter.
We don't have it yet in WA, but over East many people have to limit the amount of power they export back out into the grid. The smart meter informs the inverter what the loads in the house are and the inverter knows what the export limit is, so it then throttles back the solar power production so that Loads + Export limit = Panel production. It has to be that way, although it dismays many to see their solar production 'under-performing' because if the household loads are low, and there is a bottle-neck of how much power can be exported, then the choice is to either throttle back production or else, deal with the problem of trying to get rid of a lot of surplus solar power, perhaps expelled as heat energy. So throttling back is what happens.


Picture gallery

Below is what you see in your reporting without a smart meter.
Solar production only.


Below is with a smart meter showing what the 'self-consumption of solar is.
What the house used from the solar production (lower blue line)

The hot tub heater went on between 10am and 11.55am.


Below shows what was bought from Synergy (red line)
Note jump in power consumption midnight to 1.20am, perhaps teenagers cooking meat pies in the oven, or someone using an electric blanket.


Below, the house air con was turned on between 12.10pm and 1.10pm

It draws 8.5kW while it is dropping the temperature down to what the thermostat is set to. The solar covered about half of that, and the other half (in red), was bought from Synergy.


Below, the air con has reached thermostatic temperature at 1.10pm, and has switched from cooling to 'fan only'.
The AC power consumption drops from 8.5kW per hour to 0.8kWh and then the power use spikes a couple more times after that as the cooling mode kicks in again for a short while.