My mother would like to install solar panels on her roof but I and my two sisters would like to equally share the purchase with my mother. We would like to share the income produced from the solar panels. How do we correctly write up a legally binding contract to make this happen?
This might be more complicated than you want to handle. Depending on state and incentive structure, you might need to set up a business or partnership between you so that you can share the money flow and the tax credits.
To find out the incentives and tax credits, check out the DSIRE homepage: http://www.dsireusa.org/