I'm not always where I will have power readily available so I do what I can to mitigate this. Presently, I use a small battery pack made for charging a mobile device but it's not hefty enough to power a laptop. What I have is a durably-constructed, well-designed backpack with ample storage space for hydration bladders. What I want is an integrated charge controller / inverter and sealed lead acid battery. Basically, when I get home, I would plug the backpack in and let it charge. When I leave for the day, I would have power to last 12 hours.