You can use the sun's rays to heat up water to its boiling point, then when the water boils off, you need to capture/contain the vapour, and let it or force it to condense.
I want to desalinate this water.
Desalination (to desalinate) means to take out the salt. If you boil salt water, the water turns to gas and leaves the salt behind.
desalinate sea water
Either you melt ice, or you desalinate sea water.
The price is different for each plant.
because it has less rain
You cant filter it out. you desalinate water through evaporating the water out of the salt.
As yet is seems that it is not possible to do so. This does not mean that it can not be done.
No. You can melt ice or desalinate sea water to obtain sufficient drinking water.
The excess salt is excreted via the gills.
For the desalination by distillation - the boiling point of water. For other methods the temperature is not so important.
None: You can desalinate it, distill it, but you cannot drink seawater.