Hi Cecilia.
We have a small coworking space in Costa Rica, and our electricity goes out often enough (and rarely do we get any notice!). Sometimes for just a few minutes, sometimes for hours.
We found a small UPS at PriceSmart (like Costco) for under $100. It won’t power up lights or AC or anything major, but we can easily get about 3 hours if it’s just powering the router and wifi. It also provides another level of surge protection, plus, if the electricity goes out, there’s no interruption to internet service (no dropped calls!). But you will also need to determine how the infrastructure affects cable/fiber. Sometimes if you lose electricity you will also lose cable.
Good luck!