The R.C.D. Marshall Clinic is a project of the German Ministry of Economic Cooperation implemented by KfW/WHH/German Agro Action (Welthungerhilfe). For this and further clinics, EnDev/GIZ on behalf of WHH imports, stores and installs 13 t solar systems to provide energy for electricity in different Health Centers and Clinics. The technical design is the same in all clinics and will be described in this article. The depiction below gives a technical overview of the design of these solar systems. The numbers indicate which device belongs to which picture.
The picture shows you the solar system which is installed in all 13 WHH Clinics. You find all the devices except of the grounding bar, the batteries and the Panels in this picture. At the site we attach to every device a short explanation for the staff and all patients who are interested in solar energy.
This solar system has 4 PV Panels (1) on the roof. Each Panel has a power output (or wattage) of 315 Watt. This is the maximum amount of DC (Direct Current) output. The actual power output of the solar panels depends on various factors e.g. sun intensity at the site, clear view, no shade, etc.
The electricity from the PV (panels) goes into the PV Combiner Box (2) which brings the power output of the 4 solar panels together (combines them), so that there is only one strand of electricity.
Unfortunately, the solar Panel on the roof cannot efficiently charge the battery system in the clinic room. Therefore we have the Maximum Power Point Tracking (MPPT) (3) which is one of two Charge Controllers in this system. It transfers the DC power from the panels directly to the battery to charge it. The MPPT converts DC from the panels to lower or higher voltage DC electricity for the batteries, which means from a higher/lower voltage level to a lower/higher level according to the voltage capacity of the battery.
The Victron Inverter-1600W (4), is necessary to convert DC (Direct Current) from the battery into AC (Alternating Current) electricity. The Inverter should be switched on around 10 am and switched off at 14:00 pm if needed and no automatization programmed (like in the R.C.D. Marshall Clinic. Only in this time frame it is possible to use AC electricity for household devices. The priority is to guarantee light supply all night long for the clinic; therefore, we need to secure a certain state of charge of the battery.
The Battery Fuse (5) secures the entire system from short or hazard, it is the main disconnect for the system.
The Low Voltage Disconnect (LVD) (6) is a charge controller to regulate the discharging of the batteries and to prevent them from a deep discharge which damages the batteries over a period of time. The LVD is complimentary to the MPPT (3) Controller as it takes energy from the battery to supply the DC load.
The AC Box (7) secures that the AC (Alternating Current) electricity coming from the inverter can be used for all normal household devices (cell phone, Laptop, TV etc., no Freezer is allowed to be used on the system).
The DC Box (8) distributes the DC electricity and includes the breakers for all DC devices. Breakers cut off current automatically or manually as a protection.
The Grounding Bar (9) is a lightning protector to secure panels, inverter and Charge Controller from getting destroyed during a thunderstorm or lightning
This system consists of 12 interconnected Hoppecke opz Batteries with 2volts@255ah (10) working together as one big battery of 24-volt. A good Battery Bank is essential for the system and the most expensive part. A battery unit can last between 8 to 10 years. It is important to guarantee a certain minimum State of Charge (SOC). So it is necessary to avoid under loading as well as overloading to ensure that the battery lasts as long as possible. This is ensured by the MPPT and the LVD as the two charge controllers.
