Fuse replacement in Xantrex solar charge controller
I'm pretty sure you don't want to substitute that fuse.

First off, the original fuse was rated for 1 A, while the new one is rated for 2 A. You'll have twice the current allowed in your system before the fuse goes.
Second, the power (wattage) permitted to pass through the second fuse is 67% greater than the original fuse would allow.

Grainger has an equivalent fuse for about $12, if you've got a store around where you live or if you can wait for it to ship. Just make sure the physical dimensions match as well.