An inexpensive way of collecting power from the sun. (Heart Of Gold)
This one may actually wind up having a basis in reality: http://www.worldchanging.com/archives/002488.html(approve sites)
There is a slight flaw in the use of Solar Sheeting in the Firefly 'verse. The sheeting used on the 'Heart of Gold' is silver which would be great for keeping the sun away and keeping the building cooler inside (Which is the reason houses in tropical climes are usually white-washed), but rather breaks the rules as far as energy absorbtion goes. Joss is renowned (Must have undergone that painfull Nowning process) for great Sci-Fi but he seems to be more comfortable with the Fi than the Sci. In reality, Solar sheeting would be matt black and non reflective to absorb as much of the sun's energy as possible. The energy can be reclaimed in a variety of ways. Seeing as Kaylee recognised Solar Sheeting (Probably a brand name) then it's likely it's a system involving flexible thin-film solar cells converting sunlight into electricity which will be stored in batteries for later use. However a black absorbtive coating would probably also have water piped behind it to absorb the waste heat - this could either be used to supply hot running water for the brothel or it could be ducted away to run a Stirling engine to generate even more electricity.
As far as energy output goes, if we assume 25% efficiency for Solar Sheeting and the visible surface area of the 'Heart of Gold' then a sunny day would give you approximately 30kW of electricity from solar absorbtion alone. In contrast, the average home only requires approximately 10kW.