Spare solar energy, how to measure?

[geojay]

We have solar PV panels (1.5kw) and I'm curious about fitting an immersion diverter to use any spare solar energy for heating water rather than sending it back to the grid. Before we do that, I'd like to have an idea if we have sufficient spare solar power for this purpose, if not then it's pointless.
However, I can't see how to measure this... We obviously have the main meter which tells us how much power we consume from the grid and the solar meter which tells us how much the panels have produced but this still doesn't let us determine what has been generated but not consumed within the house, i.e. what was surplus to our needs and was exported.

Can anyone suggest a way of ascertaining this?

I'd also be generally interested in getting better visibility of our energy generation and consumption. Our solar inverter is a Fronius IG 20 and while its display gives a power reading, this isn't so useful when it's in the loft. It would be good to have a remote display or someway of viewing it on a computer or app. Is there any reasonably priced way to achieve this?

 

[JohnW2]

... We obviously have the main meter which tells us how much power we consume from the grid and the solar meter which tells us how much the panels have produced but this still doesn't let us determine what has been generated but not consumed within the house, i.e. what was surplus to our needs and was exported. ...

Are you sure that your 'main meter' cannot give you (and/or cannot be configured to give you) the information you want? Although not so-configured (since I don't have any solar generation) my seemingly pretty modest (not even 'smart') electronic meter appears to have countless registers, including ones that can be configured to record & display total kWh import and total kWh export.

Kind Regards, John

 

[ericmark]

Measuring AC current is easy, but measuring the direction is more of a problem. At 1.5 kW seems a bit pointless.

 

[JohnW2]

Measuring AC current is easy, but measuring the direction is more of a problem. ...

True, but the suppliers meters obviously have to be able to do that -and, as I said, my seemingly modest one certainly has the potential ability so to do. In fact, it can do a lot more than just measure total import and export kWh - for example ...

At 1.5 kW seems a bit pointless.

That was also my first reaction. Even at times of peak solar generation, that would not seem to leave enough which is currently being exported to cause one to get particularly excited about diverting it to an immersion!

Kind Regards, John

 

[bsr]

Please post a photo of your main meter.

 

[JohnD]

If you have access to mains gas, the cost of hot water heated by gas is so small that it is not worth investing in one of the devices that divert power to an immersion heater.

I had one myself, and did the calculations.

Some of the later solar inverters can connect to your wifi and show you what they are generating.

I get quite good savings by looking at the weather forecast and scheduling washing days so the tumbledrier will run on days when sun is expected. No other electrical appliance is worth worrying about, unless you have a plug-in electric car

I have a friend who works from home and uses an electric heater in his home office on sunny days if it's cold, but sunny days are usually warm.

P.s.
I use an "Owl" monitor and the house has a background usage around 300Watts, which the solar mostly exceeds during daylight.

 

[JohnW2]

...... <wrote the following (seemingly no easy way of inserting an image into a quote!) > ....

....maybe some unintended juxtaposition?

Kind Regards, John

 

[winston1]

I get quite good savings by looking at the weather forecast and scheduling washing days so the tumbledrier will run on days when sun is expected.

On such days I would never use a tumble dryer. Just hang it out on a clothes line.

 

[JohnD]

View attachment 270036 ....maybe some unintended juxtaposition?

Kind Regards, John

It refers to the person in the picture.

 

[JohnW2]

It refers to the person in the picture.

Believe it or not, I just about worked out that intent - but, as I implied,, that doesn't alter the fact that "Unfit for office" appears adjacent to your name

Kind Regards, John