Maybe consider a 280AH 12V Deep Cycle Battery & a 12vDC to 120vAC Inverter. Likely cheaper than a inverter generator that runs on petrol.
Likely easier to find these if there's been a run on generators in your location due to the national disaster.
Charge it up and it'll keep a basking globe running for quite a while ( P (watts) = VI.
Good quality inverters (available off shelf) will have 92% efficiency , there is some loss in electronics.
Deep discharge batteries and inverters are available at any sport and camping goods store, car parts sellers, boat shops, hardware shops, and specialist battery sellers.
So if you are running a 24W T5 tube & a 120W basking globe ==> drawing 144W , I = P/V = 144/120 = 1.2A , the battery will keep you going for eff x (280AH/1.2A) = 0.92 x 233 hrs = 125 hrs , (so good for close to 9 days before the battery needs recharging, recharge can be done from mains , or from a solar panel or if you have a 4x4 with a dual battery charger/controller in the car while driving about).
This is why grey nomads have deep cycle batteries in their campers , caravans , or 4x4s , or in their cabin cruisers.