how can i get summary of both device

Hello.

Use the Arithmetic Operation on the Virtual Value on the Dashboard.

See demo as an example

https://dash.smart-maic.com/demo

Is there any alarm for KWH limit exceeding.

In the WEB settings of the device, you can set the conditions for exceeding instantaneous data: power / current / voltage and receive an email.

On the Dashboard, you can create a simple widget with a single value and add an alert in the widget settings.