Generally, when a business wants to automate the metered billing process, they should have a back-end server that handles the metered billing readings. Once the reading is recorded, the back-end server has to process the difference between the last recorded reading and the current closing reading. If the customer has exceeded the base limit, the back-end server makes an API request to Zoho Subscriptions to update the invoice and charge an additional fee.

Let's consider the following scenario to understand this better. Zylker Electro provides electricity services to residential areas. They have a meter installed in all the houses of the residential area to record the power consumption. Every month, a Zylker personnel visits the houses in the residential area to note down the meter reading. Then, the difference between last month's meter reading and the current month is calculated. If the customer has consumed more than 500 units of power, they will charge the customer an additional 12 cents per unit.

To automate the above process, Zylker has to build a back-end server that will:

Instead of building a back-end server, you can automate the process using the Custom Functions in Zoho Subscriptions and Google Sheets. With the help of Google Sheets, you can note down all the metered readings every month. Later, you can use Google App Scripts to fetch the readings and update the pending invoice using the Custom Functions.

How can you do it?

You can use Google Sheets to note down the readings every month (similar to the image shown below).