1. Summary Thermotecnical part (Valerio) Electronic part (Matteo 2nd)
Renewable energies
Solar panels
Astronomical calculations
Electronic part (Matteo 2nd)
Temperature sensors
PLC and control tecniques
Actuators

2. Our project
One of the subjects of Comenius Project is to use renewable energy sources applied to domotica
Therefore we thought to project a solar panel plant for sanitary warm water

3. The main components of the plant are
solar panels
pipes
a pump and valves
a solar boiler
The system will be electronically controlled in order to save energy

4. The solar panel
A typical flat-plate solar panel is a metal box with a glass or plastic cover (called glazing) on the top and a dark coloured absorber plate
Sunlight passes through the glazing and the energy changing by solar into heat energy

5. … but it is possible create a solar panel also with…

6. Bottles…..

7. Captation system
A solution (water and nanti-freeze) flowing in the circuit is heated by the sun and transfers heat to the water contained in a storage tank
A pump lets the water to circulate in the system. If the water-no frost solution temperature is lower than setup value, the pump is stopped and the heating is guaranted by hot water heated by gas or electric boyler

8. Solar panel position (slope and orientation)
Solar radiation catched by fixed solar panel, especially in north regions, is unsufficient to guarantee enough hot water production
We thought to project a rotating panel able to follow the sun in order to maximize the solar radiation

9. Panel slope
The panel should be located perpendicular to sun direction when it is at its peak
Sun direction changes during the year. Therefore in winter the panel should be almost vertical, in summer almost horizontal
But in winter the radiation is weak, in summer is excessive, so we prefer to maximize radiation in spring and autumn times. In this case the angle of the sun is equal to the latitude. The slope of our panel in Modena is 44°

10. Chief parameters
Latitude Φ: angle from the equator line to our place location:
Modena 44,23° N
Beckescaba 46,69° N
Pilsen 49,74° N
Genk 50,97° N
Recklinghausen 51,57° N
Kokemaki 61,26° N Φ

11. Panel orientation
The fraction of solar radiation catched by panel depends from sun position from sun raise to sunset
We calculated the angle covered by sun for each month. It depends from the solar declination, the latitude, the daylight

12. Solar declination
δ: angle between the sun direction when it is at peak and the equator line. It is variable during the year, on 21 March and 21 September the sun is perpendicular to equator line and his value is 0; on June and December 21 it is perpendicular to Cancer and Capricorn tropic and the angle is +/ - 23°

13. The sun position
The sun position when it is at peak changes during the year according to δ and the latitude: relation is 90° - (Φ – δ)
Today february 5, the sun position on the horizont and the day light are:
Modena 29,5°
Kokemaki 12,3°
Beckescsaba 26,9°
Pilsen 23,8°
Recklinghausen 22°
Genk 22,6°

14. Calculation of each hour radiation
The data of radiation for the whole day have been taken on
thanks to this graph we calculated the radiation each hour and the fraction catched by panel

15. Panel efficiency
The efficiency of the solar panel is the ratio between the energy transferred to the fluid vector and the catched radiation. Infact a part of the radiation is reflected, a part is lost due to the environment. Therefore the efficiency is variable and depends upon the external temperature, the radiation, and the fluid temperature

16. Jan 62 55 Feb 75 66 March 96 79 Apr 123 101 May 127 108 june 144 104
Results: the moving panel tansmits to the fluid 25% more energy. A family of 4 persons needs 200 kwh in one month for sanitary water. Using 2 m2 panel we are self sufficient from march to september
Kwh/m2 per month
Transmitted by moving panel
Transmitted by fixed panel
Jan 62 55
Feb 75 66
March 96 79
Apr
123
101
May
127
108
june
144
104
July
160
114
Aug
129 92
Sept
118 98
Oct 84 77
Nov 63 56
dec 46 41

17. How does the system work?
Each sensor converts a temperature in a proportional voltage
solution
tank water

18. Resistance Termal Devices (RTD) Thermoresistors
Temperature sensors
Thermocouples
Termistors
Resistance Termal Devices (RTD) Thermoresistors
Integrated sensors

19. Temperature sensor: LM335
The LM35 series are precision integrated-circuit temperature
sensors, whose output voltage is linearly proportional to the
Celsius (Centigrade) temperature.
LM335 used
enviroment temperature
heating system temperature

20. How does the system work?
PLC controls the temperature of the water using PID regulation

21. PID
PID regulation is a mathematic calculation that allows to control a process or a system, changing the value of a signal to achieve the set point value.
This calculation uses proportional, integrative and derivative functions to maintain this value in time

22. Electronic part This device is the brain of the system
The project is controlled by a PLC (programmable logic controller) Siemens S7-200
This device is the brain of the system

23. How does the system work?
Actuator can be activated by the PLC to generate heat

24. Heating system regolation
Methods to control the heating system:
ON-OFF: the actuator (the heatresistance) is completly off or completly on at the max power. This control can let oscillate the system and stress hardly the actuator.
PWM (Pulse Width Modulation): it is a regulation technique that controls the power given to the actuator changing the duty cycle and not the frequency of the control signal.

25. What we mean to do in the future
This year:
Project pannel, boiler, pump, pipes and draw a P.& I. scheme
Introduce devices in our boiler
Make the constructive drawning of the rotating pannel
Next year: realize the mechanical structure