Given that both companies are aiming for the same well-off, eco-conscious audience, it makes plenty of sense for them to merge. Tesla CEO Elon Musk helped start Solar City with his cousins, Peter and Lyndon Rive, and also served as chairman. Musk originally positioned the combined firm as an "end-to-end clean energy" solution, and later noted that SolarCity would add $1 billion to Tesla's revenues next year. Naturally, Tesla expects the merger to also lead to savings in marketing, R&D and overhead costs.