hei. I am currently working on a project about producing electricity using solar energy, heating elements and water, and

[answerhappygod]

hei. I am currently working on a project about producing
electricity using solar energy, heating elements and water, and
need to calculate how many elements I need, to make sure that my
water heater can withstand high amounts of sun rays. assuming that
each heat element can utilize about 3 KW of solar energy
without getting damaged, how can I calculate the proper amount of
heating elements needed in order to warm up 90 000 litres of water
every day from 20 to 70 degrees celcius, while making sure that my
device has enough heating elements to not overheat and get damaged?
are there any other factors i need to take into
consideration?
thanks in advance ^.^