Enteroendocrine cells of the intestine are the most numerous endocrine cells of the body. In a sense they are known to act as chemoreceptors, initiating digestive actions and detecting harmful substances and initiating protective responses.
The typical manufacturer's warranty on a solar panel is 25 to 30 years, but panels can last up to 40 years with care and attention.
They specifically delved into what's known as payback: how many years of operation does it take for a solar panel to generate as much energy as was used in its manufacture? They found that depending on the technology used, it takes between one and four years for solar panels to earn out on their energy debt.