Sizing an Opticube

Four steps:

The selection of the right Opticube implies four steps : 
Step 1 : identify your zone geographically
Step 2 : determine your energy needs
Step 3 : identify the solar surface based on the cost reduction target
Step 4 : select the Opticube based on the surface and check the dimensions


Step 1 : identify your zone geographically

You have to spot the geographical area of your project, so that you can approximately determine the available quantity of solar energy per annum.  The different areas are stated in the following graphs and allow you to have an idea over the energy that the sun can bring to you on 1 m² during one year.


Step 2 : determine your energy needs

The energy needs is another key element in the choice of the Opticube.
If you know your daily hot water consumption, or the yearly number of kWh (or MWh) that you need, you can use your own data directly in the graphs.
Otherwise, there are some techniques commonly used to calculate your consumption.
Then, the results are brought on the x-axis of the graph which corresponds to your zone.
Daily hot water consumption (60°c) :
- Shower : 35 l/shower
- Bath : 80 l/bath
- Hotel room with shower : 75 l/overnight stay
- Business restaurant : 4 l/tableware
- Sanatorium : 30 l/bed
- Hospital : 55 l/bed
- Camping : 12 l/shower
- Pool (showers) : 15 l/swimmer
- Pool (water renewal) : 10 l/swimmer


Conversion in kWh based on gas or fuel consumption :
(Those formulas take into account the average effectiveness of boilers)
Fuel :  Consumption [kWh] = numbers of consumed liters x 8
Gas :  Consumption [kWh] = number of invoiced kWh x 0.8
1000 kWh = 1 MWh

Step 3 :  identify the solar surface based on the cost reduction target (percentage of economy you wish to obtain)

Now that you are able to quantify your consumption, and thus the number of kWh (or MWh), you can use the graph of your zone to define the right surface of collectors:

Example: In Paris, an hotel with 130 rooms and a 80% occupation rate wants to generate 55% of cost reductions on the hygienic hot water. Consumption= 130 x 0.8 x 75L= 8 000L/Day. With 300 m², it will save 55%.

Example: Near Genève, a food processing industry consumes 37.500 l of fuel per year and wish to generate 60% of cost reduction thanks to the solar system. Energy need = 37 500 x 8 = 300 000 kWh (300 MWh). With 250 m², 60% of cost reduction will be generated

Example: Yearly, in the south of Spain, an hospital consumes 500 000 kWh of gas for hot water. The target is to find a system that would be able to produce 4/5 of its needs for the next 20 years. Energy need = 500 000 x 0,8 = 400 000 kWh (400 MWh). With 400 m², it will reduce massively his gas consumption (-80%).

Step 4: select the Opticube based on the surface and check the dimensions