How to choose PV Battery for BSP300 Base

How to choose PV & Battery for BSP-300? Base on optimal assumption!

Outline u Assumption of usage in optimal case u Factors in the PV and Battery installation

Assumption u System Requirement & Assumption ü BSP-300 system: 8 Watts ü 1 x 25 W AT Camera: 25 Watts ü 1 x 802. 11 a/n AP: 7 Watts => Total: 40 Watt/hr u Environment Factor (Optimal Case) ü 8 hr sunshine at daytime ü 16 hr power consuming from battery at nighttime • We got 40 w x 16 hr (640 Watts) per night consumed • The minimal battery capacity required should be 640 watts – 640 W/24 V = 26 Ah (i. e. 12 VDC Battery 26 Ah x 2 required) • Also, that is 80 watt/hr (640 w / 8 hr) need to be reserved for charging

Get the first PV required u How it calculated ü PV power up the system & device ü The rest power budget then be used for charging PV X watts X – (Y+Z) = N N then is the budget for Charging So in optimal case: X = Y+Z+N = 120 W That is base on the 120 W / hr Battery N watts 80 W / hr For charging assumption 120 W PV required. BSP-300 Y watts Device Z watts 40 W / hr to power device

Factors in the Battery Installation u Environment Factors ü Duration of Sunshine • How long for PV to power the system and also charge the batteries ü Battery Efficiency • There are discharge efficiency that effect the capacity of battery ü Temperature • Temperature will effect the efficiency of batteries for discharge and charge

Factors in the Battery installation u Duration of sunshine ü Need to check the Weather Bureau for average hours per day locally ü Need to check the cloudy day duration (say, the cloudy day will lasting for how many days) Battery Not only sustain for Day at 1 night Discharge Charging Sunny Discharge Cloudy Day 2 Charging Cloudy Battery need to sustain for upcoming days’ insufficient charging Discharge Sunny Cloudy Sunny

Factors in the Battery installation u Battery Efficiency ü Different Battery will have different discharge efficiency • Lead-acid, for example, 70% ~ 80% Charge 100% IN Discharge 70% OUT

Battery Capacity Formula u Assuming the battery capacity formula ü C: Capacity (Ah) ü W: The system load (W) ü T: Discharge hours (h) ü Bf: Battery Discharge Efficiency ü Vs: BSP-300 cut-off voltage (to protect battery over discharged) ü Dc: Cloudy days of the area C= Wx. T Bf x V s x (1 + Dc) u So previously, we have 26 Ah Battery ü u C = 40 W x 16 h / 24 V Then the one close to the real environment will be ü C = [(40 W x 16 h) / (22 V x 0. 7) ] x (1+Dc) =42 Ah ü We got 42 Ah (assuming no cloudy days) ü And if with 1 cloudy days ü C= [(40 W x 24 h) / (22 V x 0. 7) ] x (1+1) ≈ 120 Ah

Factors in PV u The PV is also with Efficiency ü Say for example: 80% ü So the new PV required will be: • N = (640 W (sunny day 1) + 960 W ) / 8 = 200 Watt • PV = (200 Watt + 40 Watt) / 80% = 300 Watts (cloudy day 2) u To apply to your system, please check the Excel work sheet below.

Factor in Temperature u The Temperature also will effect the efficiency of battery the battery should installed in a shelter to provide stable and reliable power for BSP-300 system.