It depends on the size of your sales pipeline; if small or just starting out, a senior/lead should be able to do sales as well but not everyone is good at it. I've done each & both together. Solution design and pre-sales work aren't always compatible due to different turnaround times so prioritisation if being done as a combined role can be challenging.
Too little detail. What is your product? How technical is it? What stage of development is it in? How big is this team (sales/eng)? What happened for this question to arise?