Requirements for Hot Water

When choosing a solar system for hot water, we must first determine our need for hot
water, in quantity as well as in preferred temperature. The typical temperature used for calculation is 45°C, but the required quantity must be calculated according to specific daily  needs.

Hot water usage calculation

Residences

In family residences, the needs for hot water remain stable during the whole year. An indication for the needs is given by the number of individuals living in the building (or apartment). Usually, the per capita daily consumption of hot water at 45°C is calculated taking into consideration of the following:
Low consumption: 35 liters per capita / day
Medium consumption: 60 liters per capita / day
High consumption: 80 liters per capita / day

In the case where we want to connect the solar installation to the washing machine and
the dishwasher, we would have to increase the calculated daily needs of consumption as follows:
Washing Machine: 20 liters / day (1 wash per day)
Dishwasher:      20 liters / day (1 wash per day)

Example:
A family of 4 needs around 240 liters of hot water daily in order to have a medium daily consumption. (60 liters per capita x 4 persons) If we include a washing machine and a dishwasher, then we must calculate a consumption of 280 liters per day.

Hotels - Hostels

In buildings such as hotels, hostels, etc..., the needs for hot water are related to the
number of guests. In this case, the daily consumption is calculated by the average
occupancy of the rooms, from the period of May until August. Using this basis, the size
of the proposed installation is determined. Here below we indicate the per capita daily
need for hot water at 45°C.
Hostels with shared bath: 35 liters / person / day
Hotels: 40 liters / person / day
2 Star Hotels: 50 liters / person / day
3 Star Hotels: 80 liters / person / day
4 Star Hotels: 100 liters / person / day
Camping: 60 liters / person / day