If one of your questions asks for email, you can use that field in the Notifications & data screen to send confirmation.
Let's assume you have a question with the question code Email
First we need to trick the system into wanting to send the confirmation email, so:
1. Go to Settings->Email Templates
2. Click on the tab "Confirmation". Copy the contents of this email to the Basic admin notification tab
3. Save this page
Now we can tell the system to send the basic admin notification to the participants email address:
1. Go to Settings->Notifications & data
2. In the field "Send basic admin notification email to" paste your question code, wrapped in curly brackets. So in my example, if the question code is Email, you would enter {Email} -- note that question codes are case sensitive so be sure to use the correct format.
3. Click Save.
Now, when the survey is submitted, the basic admin notification template will be sent to the participant -- and since you copied the Confirmation email into the basic admin template, this is what the participant will receive.