Do they at least have access to cold water and/or ice? If not, it's much cheaper to have enough fridges and/or freezers and/or ice makers to keep every student supplied with cold water, ice, cold wet towels, etc. The money it takes to give half the school ACs could give the entire school cold water and ice with money left over to fix the solar panels. The electricity from the solar panels is also more well-used this way because the heat pump compressors are basically focusing on using (thermally dense) water and ice to remove heat straight from the human body instead of (thermally weak) air to remove heat from entire rooms.

It's important to position these things well though. They're not so useful if they're in a closed room with the students, they need to be where the heat can get away from the students. ACs are made to have this figured out for you, just put in window and heat gets pumped out the window. Sufficient AC is also more comfortable, but simply not affordable for as many people.