From Earth River Geothermal
Located in Annapolis and serving Central Maryland, Earth River Geothermal is your locally-owned, full-service geothermal heating and cooling systems provider. If your personal priority is saving money, creating a more comfortable home or saving energy, Geothermal is the way to go! In fact, there has never been a better time to use a geothermal heating and cooling system to more efficiently heat and cool your home Historic federal, state and local geothermal incentives are in place that can significantly offset the cost of installing a geothermal heating and cooling system. Ground source geothermal heating and air conditioning systems are "the most energy-efficient, environmentally clean and cost-effective conditioning systems available".
Facebook: 5/5 
BBB: A+
Make that 4+. We got three bids and Earth River gave us the best deal and the best feeling about overall competence and responsiveness. They underbid the others by over 10%. Also, when county issues came up with sewer setbacks, Mark Schultz adeptly found the way through it. He and Terry Bair coached us on every aspect of the job and it turned out great. The system is well designed, made from high quality components, and works beautifully. Our only complaint is a chronic one for construction jobs. Everything takes longer than estimated or hoped. When the interior work began, however, things moved quickly and on schedule, which is important for work on an occupied home. For what it's worth, we suggest using an Ecobee thermostat rather than a Nest (which was our previous thermostat).
I thought Earth River Geothermal did an excellent job! We had a vertical heat pump put in by them replaces a two heat pump system in our house. They were professional and efficient in getting the job done, and everything has been working great. They also were very helpful in getting all the paper work done for the grants/tax rebates.