Alternative electric source

Here are the realities in a nut shell. Some of your desired devices like chick brooder heater are power hungry. They would need a LOT of reserve battery power. The water warmer could get by with low to medium power usage. The light can be a solar powered unit that works for free.
So the light easily solved, the option for a water warmer would be a Deep cycle Marine Battery with an appropriate power inverter to run an aquarium heater. You would have to determine the size by the size of water container to heat, and the size of aquarium heater needed to do such. The temperature of the winters where you live being a big factor. You would need to bring your battery into your facility to recharge as needed. Maybe on a weekly basis??? .. Your brooder heat can be achieved, but with more batteries, at which point may be more effort than the value.
Some of this setup can run into Extended ca$h,,, with the solar light being the cheapest option. Batteries would be $100 plus , each. Power inverter $100 to $200 depending on capacity. A battery charger, about $50. some are available for less, but slower charging time. The next thing to consider is a place to keep all these item protected from the outside weather. If your coop is large, then inside a dry place and separated from chickens jumping on all the equipment would be fine.
WISHING YOU BEST ...

 

I have a little solar panel on the roof of the coop to provide an interior light. It's very dim (on purpose) and casts a soft glow since I only need a little bit of light inside for about 15 minutes each evening. I know there are beefier solar set-ups that might be suitable for your purpose, but all I needed was some light so I didn't investigate the other options. If I'm broodering chicks, I run an extension cord to the coop for the heating pad since it's a temporary situation and my coop is close enough to electricity to do that. A bigger solar panel with a battery might work for your situation. If you brooder with a heating pad instead of using that ancient torture device called a brooder lamp, your electricity needs won't be as great.

 

How far will the coop be from the nearest source? Anything that generates heat is going to draw a good bit of power. Any kind of system to supply much more than a few bulbs is going to be pretty expensive. A solar/LED light setup wouldn't be too bad though. Would it be worth running an extension cord for the "short" periods when you need the electric?
Best of luck to you!

PapaBear
No Clucking Around

 

There are many solar power systems out there, they can get complicated and expensive if you need more than just a bit of light.
Most are not just 'plug and play', there may be several components you will need
.
What is your climate/location?
Are you sure a good long heavy duty extension cord might not work for you in winter?
I just use a headlight for headcounts and simple chores in the dark.

Might start to learn about solar options by reading thru these threads:
Advanced search>titles only>solar power