At the barn where my horses used to be, there was no electricity either and the BO bought a solar light to put inside the hay barn. (that same one from the link you posted) Still no light outside the barn. Interestingly enough, I have to say, his barn was very VERY dark, no natural light unless a door was opened...if any natural light gets into the barn and you want more light...the solar light doesn't seem to help at all. This solar light worked best in complete darkness.
Anyway, from having NO light, to enough light to see to feed, I'd say it did the job. That being said, you can get as much light, or more by using the LED flash lights, work lights, lanterns...etc.
My hubby bought me a ball cap with an led light in the bill...That was my favorite thing all last winter! It actually had 3 little LED lights in it, and I could click, 1, 2 or all 3 depending on how bright I needed. My hands were free and I could focus the light everywhere I looked.
It's very frustrating to have no barn lights during the winter months, that's for sure and now I'm a little bit spoiled as there is a light in the new barn who knew I' one day consider light in a barn a luxury!
Good Luck in your lighting endeavers.