Hi Robin2,
Following are the system design inputs,
1. Solar SPV Module - Synergy SRE200 series module, - 5 nos., 200 Wp each, Vmax - 27 Volts, Imax - 7.41 Amp. I intend to use them in series to reduce current rating of connecting conductors.
2. Battery Bank - I have calculated required battery bank capacity to be 24 Volts, 360 AH (rough estimate). We may use 48 Volts, 180/200 AH bank as this is nearer to standard available battery/cell capacity.
I have gone through some standard products in market. Here, modules are connected in parallel to get a 30 Volts max charging system to charge the 24 Volt battery bank where, standard 12 Volts, 180 AH batteries are connected 2in series and 2 in parallel. However as far as I know connecting batteries or cells in parallel is not recommended, as also the module to charger and charger to battery connectors are very thick. Moreover, The charging section, though called PWM charger, does not contain any inductor. I think they are basically simple ON/OFF controller to control the charging current. the Other problem is highly discontinuous battery current during current limit operation which reduces battery life. However, as the MOSFETs mainly operate in DC conduction region, they are highly efficient due to near zero switching loss. I intend to reduce the conductor size, hence the choice of higher module bank voltage, battery bank voltage is higher as I can use standard batteries/ cells in series, and a proper SMPS charger to provide continuous current even at current limit. However, the efficiency must be high to compete with the normal charger available in market. I also think using SMPS charger along with a Microcontroller (which is available at hand to control the Sine wave inverter circuit) can ultimately result into design of a MPPT charger. The control technology can be developed. But the bottom line is the Efficiency of the charger.
Can you help me in any way.