Photovoltaic (pv) power systems less reliable component is their power interface, which usually includes a dc-dc converter due to its low dc output voltage. Therefore, fault-tolerant strategies applied to their power interfaces are mandatory. Redundancy is the most common fault-tolerant strategy, but it increases the system costs without necessarily improve its performance. Therefore, a cost-effective fault-tolerant strategybased on the modularity of interleaved dc-dc convertersis presented. Besides greatly improving the pv power systems reliability, it provides a better performance when compared with conventional dc-dc converters.