Efficiency isn't quite the important thing for solar as it is for fuel burning engines since all the sunlight is used up at the same rate no matter how much pow

Efficiency isn't quite the important thing for solar as it is for fuel burning engines since all the sunlight is used up at the same rate no matter how much power you capture from it. We could get much cheaper panels with no better efficiency and that would still be excellent. More important than energy efficiency is price per unit energy. You could have an inefficient but cheap solar cell that's more economical than an expensive efficient one (eg. active tracker vs fixed - the less efficient option is usually more economical). Though when installation costs dominate, then you really do want smaller panels so you can spend fewer man-hours nailing them up.