Depending on whether you have a CT clip sensor or LED sensor this might be for a couple of reasons. Please see both below:
With an LED sensor the Solo II should always match the meter. If it does not you may have the wrong pulse rate set on the display.
To check the pulse rate, search for the rate on the front of the meter. It is usually located near the pulsing light/LED and will look similar to: 1000 imp/kWh. Now on the Solo II display go into the menu (hold the middle button) and choose the Advanced option. Press the middle button a few times until Pulse rate is displayed – this rate should match the one on the front of your meter.
If this does not fix the issue or the pulse rates already matched, there could be a problem with the light from the pulsing light/LED on the meter reaching the sensor. Try reseating the LED sensor on the meter ensuring it sits directly over the light.
CT Clip Sensor
With a Current Transformer Clip your Solo II needs to make a number of assumptions to calculate the kW readings it shows you. If you think the readings are inaccurate you can recalibrate your Solo II from the C-Factor subcategory of the Advanced settings menu.
The C-Factor (calibration factor) is set to 1.00 by default. It can be adjusted in increments of 0.01 from 0.5 (-50%) to 1.5 (+50%).
To work out whether your Solo II is over or under-reading you can run a small test:
1. Take a reading from your electricity meter in the morning at a time when there is not much load on in your house and note down the ‘TODAY’ reading on your Solo II.
eg. Meter reading: 00324.5
Solo II: 1.500kWh
2. Wait at least 10 hours. During this time use your household appliances as normal. Do not run this test over night!
3. Take another reading from your electricity meter when there is not much load on in your house note down the ‘TODAY’ reading on your Solo II.
eg. Meter reading: 00332.5
Solo II: 10.150kWh
4. Work out the difference between your electricity meter readings.
eg. 332.5 – 324.5 = 8
5. Work out the difference between your Solo II ‘TODAY’ readings.
eg. 10.15 – 1.5 = 8.6
6. Compare the two readings and work out the calibration or correction factor.
eg. Meter reading / Solo II reading = Calibration Factor
8 / 8.6 = 0.93023
7. Round up the calibration factor to the nearest 100th and adjust the C-Factor in the settings menu to match.