# How to calculate the heat input of SPRING panels?

The caloric contribution of the DualSun SPRING panels** on a solar tank or swimming pool is calculated using the formula for the amount of heat**.

The input data are:

- The temperature difference between the inlet and the outlet of the panels
- The volume of fluid transported through the panels
- The heat capacity of this same fluid (i.e. the amount of thermal energy it can transport)

The formula for the amount of heat is as follows Q=mCpT

- Q in J
- m mass of the fluid in kg (i.e.m=Dhuse),
- Cpmass heat capacity of the fluid in J.kg-1.K-1
- T = T°panel output-T°panel entry

Cp 40% glycol water = 3.5 J.kg-1.K-1

Cp salt or chlorinated water = 4 J.kg-1.K-1

To learn more about the actual performance of our panels, you can consult our blog.