
Your products will appear in Google Shopping if they have product ratings. This is one of the most common ways for shoppers to search online for products. You can give searchers a rating to help them decide if your products are worth their time.
Star rating on Google Shopping listings allows searchers to quickly compare different options. This makes it more likely that your Google Shopping ads will get a high click rate. You should note, however, that ratings can only be displayed on your Google Shopping Listings if you've met all requirements.
For Product Ratings to appear on your listings, you need to submit a review feed in the Google Merchant Center. The reviews feed consists a XML-file that includes information about the products and reviews. You will need to update your feed monthly in order to keep it valid.
Also, make sure that all your reviews are in line with these quality guidelines.

The best reviews will be informed by in-depth research, real subject-matter experience, and should reflect this. This will allow your reviews to stand out from others and help you attract more customers.
This is a great place to start because it's an easy, free way to build a strong online reputation for your business. You can even use it as a way to gather testimonials from your most loyal customers.
To get started, create a Google account. It may take up to a few weeks before you can get started, so be patient.
After you've created your account, you can create a Google Shopping ad campaign with the goal to drive traffic to your store or convert sales. The ad must include your reviews and the average star rating you have for your products.
These ratings can be displayed in your Product Listing Ads and Catalog. This can increase conversions from customers searching for specific products on Google. This feature is available for all countries in which Google Shopping is currently active.

A good reputation is essential for any eCommerce company. Google's product reviews program can help boost sales and improve customer satisfaction. It's easy to set-up and only requires at most 50 reviews on all your products.
Yotpo will automatically feed your reviews and display them on your product details page. You can also add user generated photos from your site.
Product Review Program: How it Works
Google's product review program is a free service that helps retailers collect feedback on their products. This program sends emails to customers on the day of their expected purchase and asks them to rate products purchased from you.
After you submit a review, your feedback will be sent to you by email and you can view it in Google Merchant Center. You can also use the feedback for product improvement.