Looking at the electricity bill is pointless, as with solar we would run air conditioners all day everyday, something we don't do now .

We could turn on all the air conditioners (and everything else) from 9am to 5pm and measure the numbers at the meter then divide by 8 to get the average Kwh that we need the solar to produce and feed us with . Would this provide an accurate number for the Kw solar system we would need ?

There are also clamp meters, and Wifi Clamp Meters .

Tuya แคลมป์มิเตอร์ Wi-Fi (รุ่น PJ) วัดพลังงานไฟฟ้าได้ 2 ท...

Tuya แคลมป์มิเตอร์ Wi-Fi รุ่น PJ วัดพลังงานไฟฟ้าได้ 2 ทิศทาง ขนาด 80A ดูค่าและประวัติผ่านแอป-Clamp Meter

Is it a case of only clamping this around the 25mm government electrical cable that runs to the house and electrical mains, at the entrance point to the house, or does it need to physically be attached to the electrical mains with the live wires running through it?

It's as simple as clamping this onto the PEA 25mmsqm cable that powers the house, and then reading the data off the APP ? And that then will give us the information about what size solar system we need ?

Ideally you need it to log and graph the energy usage throughout the day.

You can get a good idea by reading your meter at 8AM and 5PM (more often if you like) so you can graph your day/night usage.

Lots of day = loads of panels, lots of night = mucho battery.

2 minutes ago, Crossy said:

Lots of day = loads of panels, lots of night = mucho battery.

The plan is to get the panels first, then the battery at a later date. It is to power 2 to 3 aircons from sun up to sun down, as well as normal household appliances .

2 minutes ago, Crossy said:

Ideally you need it to log and graph the energy usage throughout the day.

Does a WiFi clamp meter, that apparently simply clamps around the PEA wire providing the house's electricity do that ?

The clamp measures current, the beast also needs mains power so it can also measure energy.

You need to verify what the associated App actually does.

Do you have actual links to the devices you are looking at?

1 hour ago, Crossy said:

The clamp measures current, the beast also needs mains power so it can also measure energy.

You need to verify what the associated App actually does.

Do you have actual links to the devices you are looking at?

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I am not fully aware of just how they should be installed, I believe the non-intrusive is the term for not having to attach it to live wires within the home's electrical system.

If there is a device that just clamps around the PEA electrical cable where it enters the house, that is what I'm looking for.

This is the approach I took for whole house energy monitoring.

53 minutes ago, Bandersnatch said:

This is the approach I took for whole house energy monitoring.

That's great , thank you.