However, such back-up power increases the overall costs of the systems. Other types of hybrids are also possible, such as photovoltaic-wind hybrid systems, which take advantage of the varying availability of the solar resource and the wind resource, allowing each renewable resource to supplement the other, and increasing the overall capacity factor. This includes, for instance, the introduction of off-grid solar PV products that are much smaller than the traditional 20-50 watt solar PV systems (sometimes called “pico-PV”).