A manager at the GreenTech Energy Corporation claimed that the expenses associated with developing new solar panels should be covered by government funding, arguing that the sales of solar panels are expected to be less lucrative than those of other energy products. To support this assertion, the manager pointed out that each solar panel is typically sold once to a customer, while other energy products often require repeated purchases.

Which of the following, if true, most undermines the manager's argument regarding the sales of solar panels?