Saving the environment can start with cleaner water-heating devices. Many different water heating systems exist, including tankless solar powered systems. These devices may be installed in any sunny location, even on your roof.
This is a simple Joule Thief like circuit that works as a solar night light.
Minimize the upfront costs of solar panels by considering a lease instead of a purchase. This spreads the payments over a long-term period into monthly installments, so you could actually start saving money immediately. Still, consider how long you will be in that building, as the long-term periods usually run a decade.