FR-2 Power

I realize that power has been discussed here many times but I'm not
getting good leads on my problem from old posts.

My kit is of the small, over-the-shoulder variety and is for low budget
production as well as sound effects recording. I have no sound cart,
big mixer or monitor to power, just my FR-2, and I'd love something
portable if possible. Secondary concerns would be expandability and
solar recharging, but portability is the prime concern. Many thanks.

Arnold