@Nusrat12
First, as others have mentioned, don't give guests control of the thermostat. Get something you can control from your smartphone. It's cheap, and will enable you to have control. Guests aren't thinking about that when on holiday. Just don't give them the ability to mess with it.
Another smart thing to do is to install supplemental solar power. It's getting really inexpensive now, especially if you have someone - a friend or whatever - who understands electrical installations (it's not complicated), rather than hire a professional who will charge the max they can get. My husband did ours, but he's an engineer. Nonetheless we spent less than 1/3 of what the pros quoted and got much more energy for that money.
You can buy reliable high capacity hybrid charger/inverters for a few hundred bucks nowadays that support grid energy as well. Panels are cheap nowadays too. It's batteries that are expensive - but you don't necessarily need them if you have grid power, although you can always add them when you have the funds available, which will keep you powered when the sun isn't shining, without using expensive grid power.
Most of the new systems are modular, so you can start small, easily add on when funds are available. We started small and added on every year it was easy. Now everything is powered by the sun. A/C, heating, pool, the whole house. No electrical bills at all. And in the 40 degree heat of summer and in 5c winter nights, the house comfortably stays at 22-23c. Guests are very happy with that. Yet they have no thermostat available for them to screw it up.
In any case, you'll start to see a reduction in electricity bills immediately, and as you scale up, the bills will be less and less, until you scale up to a point where they go to zero. Totally solar powered.
Good luck with everything.