One of the first issues is the orientation of the house. Solar panels do better on the south side. You should research whether your roof needs to support more weight. You will also do well to consider all aspects of solar building --- you can find books available in e-format for this. Go to Amazon and read reviews carefully. Things like roof overhang, kinds of windows, etc, can make a big difference in cooling your house (I'm assuming in India, heating isn't a big issue). For the solar panels, what's available where you are is a starting point. I will note that in sunny countries, like Turkey and Tunisia, I see a lot of solar hot water on roofs, but not so many solar panels.

Search Houzz "Browse Rooms" and look on the left hand side menu for bedrooms, you will find 1,000s of photos to give you ideas. If you can give more details like where the door is and windows, we can perhaps suggest ideal placement. All the best

We are building as well, our ensuite is similar size. We are having double tiled shower, double vanity and toilet. We didn't separate toilet as it was a added cost and didn't see the point in the master

It's a great way to collect photos of images that you like for your house using the "Ideabook" system. If you haven't designed the house yet, you can share these photos with your architect or designer to give them ideas of what you like. If you are at the point of decorating you can put together an ideabook for each room in the house. You can even ask you family members for their input by having them do their own ideabook. If you have a specific question, you can post it in the "discussions" and you will get opinions and answers from all over the world. It's a great way to design your space.