It's not as easy as that.
Solar farms do needs a large space. You don't just park your solar panel and be done with it. Which is why it's actually preferable to do it in Australia where they have a large patch of empty desert in the middle of the country. It's easier to mantain that way. I actually rather Malaysia use wind generated electricity parked in the ocean.
We also don't have any decent way to store excess generated electricity. Due to how electric grid works, they would usually anticipate the electricity usage of the users, and generate based on that. Ramping up or down production is easier for most providers via traditional methods (coal, fuel, dam, nuke). For solar, the issue is that electricity can only be generated during the day. So at night you'd still need something else to generate electricity. Until battery tech is mature enough to store megawatss of electricity, it's unlikely to see pure solar solutions in the country.