Do keep in mind that while they are "cost effective" - it takes a few years to recoup the initial investment.
A more efficient panel will repay its value sooner, or will require lower initial investment.
Second, the possible applications -
Low efficiency cells will support low power appliances,
Or you'll need more of them / storage for more power hungry applications.
A more efficient cell enables new applications where weight is an issue.
Second, the possible applications - Low efficiency cells will support low power appliances, Or you'll need more of them / storage for more power hungry applications. A more efficient cell enables new applications where weight is an issue.