Tip #8 : Implement metered billing with Google Sheet

Tip #8 : Implement metered billing with Google Sheet

Hello everyone,

We've been sharing a tip every week to address specific business scenarios which can be implemented for your subscription business. Last week, we shared a tip about integrating online form builders with Zoho Subscriptions. This week, we will be looking at how you can implement metered billing in Zoho Subscriptions with Google Sheet.

Business Scenario:
Metered Billing  is the concept of charging your customers based on their usage of a product of service. With Zoho Subscriptions, you can charge your customers for a base plan initially and then charge an additional fee based on their usage using metered billing.

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:
  • store the meter readings;
  • calculate the power consumed for every month; and
  • charge the customers accordingly.
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).




Field
Description
Last Recorded Reading
The meter reading at the end of the previous month.
Closing Reading
The meter reading at the end of the current month.
Status
The field is used to specify whether the invoice for a customer has been updated in Zoho Subscriptions or not.
ID
Unique Ids that are used to map the customers between Google Sheets and Zoho Subscriptions.

Google allows us to access and edit the data in spreadsheet with the help of Google Scripts. Coming back to the scenario, every month a Zylker personnel will record the readings in the Google Sheet. With Zoho Subscriptions, you can configure a custom function to run for the invoices in the Pending status. You must configure the Custom Function in such a way that:
  1. it fetches the meter readings from Google Sheets using Google script;
  2. processes the data and adds an additional charge to the invoice, if needed (based on the consumption);
  3. updates the Status in Google Sheets as Updated; and
  4. updates the Last Recorded Reading with current month's closing reading.
Once the custom function executes successfully, the invoice will be updated with the additional charge. The value in the Status field of the Google sheet will also be updated.

Getting started with Google Apps Scripts:

 Google Apps Scripts provides you with feature-rich APIs that allow you to build you own web applications. For our scenario, we will be using the Spreadsheet APIs to fetch and edit the spreadsheet document. We will create two scripts:
  1. The first script will be used to fetch the last recorded reading and the closing reading of a customer.
  2. The second script for changing the Status field of the customer once the invoice is updated.
To create a script in Google App Scripts:
  1. Go to and click the New Script option on the top-left corner.
  2. Copy the scripts provided above and modify it to suit your needs.
  3. Once you are done, click the Publish option on the top and select the Deploy as web app option.
  4. Provide the project name.
  5. Choose Anyone, even anonymous in the Who has access to the app dropdown.
  6. Click the Deploy button.
  7. Save the Web app URL which will be displayed on the screen for future reference.
Once the Google app scripts are successfully deployed:
  1. Create a new Custom Function in Zoho Subscriptions.
  2. Choose the Module as Invoice and Predefined event as Invoice created.
  3. Copy the Custom function from this GitHub link and modify it as per your requirements.
  4. Save the Custom Function and you are good to go.
Found this useful? Try it out for your subscription business and let us know. If you have any queries, feel free to comment below. We are here to answer them.

Cheers,
Sasidaran K,
The Zoho Subscriptions Team.