Whether
it is because you are away from the power grid, or the grid is down
because of emergency conditions, you may face the prospect of making
your own power.
Fortunately,
this is easy to do if you are prepared and do a little research.
Getting power from the sun is a proven technology and has been used
for decades in spacecraft like this GPS satellite.
Your
remote/emergency power needs can be partially or fully met with solar
power by using one or more photovoltaic panels and a battery storage
system.
Solar Power 
Getting power from the sun is a proven technology and has been used
for decades in spacecraft like this GPS satellite.