If you are trying to figure out whether or not it makes economic sense to invest in solar energy at your hotel or inn, I recommend checking out several sources available at the American Solar Energy Society website. The first source, an article entitled, "What Does PV Cost?", explains that determining the cost of an electricity-generating photovoltaic system is not a simple process. There are many factors that come into play: worldwide price of silicon, competitive scene in module distribution, local costs for labor and materials, availability of incentives and rebates, etc. The article includes links to an online calculator to help one determine cost.
A second article tackles the issue of determining the financial value of a solar or wind energy system. For example, in areas where electricity costs are higher, solar and wind systems have more value. Of course being able to sell electricity one generates back to the utility is also important. This can be done in 42 states in the United States thanks to net-metering laws. Incentives and tax benefits also should be considered when determining system value.
The website also includes an article that includes a link to a spreadsheet that allows one to calculate the payback time and internal-rate-of-return for a proposed photovoltaic project. A significant amount of preparation is required prior to using the spreadsheet. For example, it asks for the annual energy output of the solar system as well as initial system cost.
Shopping for a solar system can be an intimidating process. Make use of the tools found at the American Solar Energy Society website. And, be sure to pick the brains of knowledgeable vendors. They should be able to answer any questions you may have, especially those in regard to available rebates in your area.