The idea of developing new, innovative, low-cost solar collectors for large solar system design is emphasized towards making this technology feasible. The design principle of new low-cost modular solar collectors made of recycled low-cost polymer materials is presented, and their efficiency factor and overall loss coefficient is estimated for the low thermal conductivity materials involved. Based on derived results and system components assumptions, long-term performance investigations were conducted for typical load and meteorological conditions corresponding to a sunny Mediterranean country. Results from those investigations, combined with the estimated cost of proposed collectors and current costs of conventional collectors, were employed for comparative evaluation of the payback period, which indicates the importance of design innovation for the commitment-based promotion of large solar systems technology.