My SolarEdge Monitoring Doesn't Look Right

If you've got a SolarEdge inverter with consumption monitoring and it is not working properly, i.e. the graphs make no sense, or the graphs are massively overstating your consumption then your problem is that the consumption CT (Current Transformer) has been installed backwards.

This is what the SolarEdge CT looks like. It opens up, and the wire whose current you want to measure simply goes through the square hole:

I recently fixed my friend's Solar Edge monitoring which had never worked properly since it was installed 6 months ago. The installers, Bradford Solar, were stumped, and he was tearing his hair out.

What the monitoring looked like before I fixed it:

Look at the graph above, it is obviously wrong.

The graph claims the house only uses electricity between 7:30am and 5pm. That's a load of rubbish!

And no-one's consumption perfectly matches the shape of their solar generation.

When you see this pattern on your monitoring, then it is almost always due to one of the CTs being the wrong way round.

With single-phase Solar Edge monitoring there is only one CT : the CT that measures the current going to and from the grid. This CT is on backwards!

Why does the CT have to be the correct way round?

If the CT is the wrong way round it will get the direction of the current flow wrong.

Remember that the solar edge CT is installed on the wire that goes out to the grid.

It needs to know when the current is flowing to the grid (exporting) and when it is flowing from the grid (importing). If it gets these the wrong way round the maths doesn't work.

Here's why:

The Solar Edge monitoring needs to tell you what your house consumption is. But the current measuring CT is not installed on the wire going to your house, because there is not one single wire going from the meter to your house - there are dozens!

Instead, the CT is placed on the single wire coming from the grid.

As you can see from the diagram above, working out the house consumption is simple if you look at the arrows in and out of the meter.

HOUSE CONSUMPTION = SOLAR - GRID

For example: if the solar is pumping out 5kW and the 3kW is going to the grid, then the house must be using 2kW. Simples.

But if the GRID CT is the wrong way round then the 'sign' of the grid consumption is wrong.

So when the Solar Edge box does the sum it is:

HOUSE CONSUMPTION = 5kW minus -3kW 

If you paid attention at school you will know that subtracting a negative is the same as adding the absolute.

So the solar edge with the backward CT will think that the house consumption is 8kW!

With my friend's system, I simply unclipped the CT and turned it around and re-clipped it. 

Note that legally, you need a qualified person to do this as you are going into a switchboard with deadly voltages in it. So get your installer to come back and do this for you.

Lo and behold all my friend's monitoring problems are now fixed. You can see that the graphs actually make sense now and he can get on with the job of analysing his consumption and getting his bills down.

Green = Solar

Red = Grid Imports

Blue = self-consumed solar