# 12v 24v solar battery calculation II

- Jan 13, 2019-

Calculate the battery panel:

1. LVD lamp 40W, current: 1.67

2. Discharge time of 10 hours per day (take 7:00 p.m. - 5:00 a.m. as an example)

3. Reserve at least 20% of the batteries.

4. Local effective light is calculated with an average of 4 hours per day.

WP_17.4V=(1.67A*10h*120%) _4 H

WP = 87W

The actual constant current source loss, line loss and other comprehensive losses are about 20%.

Actual demand for battery panels = 87W * 120% = 104W

Actual batteries require 24V/104W, so two 12V batteries are needed: 208W.

Integrated component price: positive battery board 191W, 31 yuan/watt, 6448 yuan

Battery 300AH, 7 yuan/AH: 2100 yuan or so

40W LVD lamp: about 1000 yuan

Controller (only) about 150 yuan

About 700 yuan for 6m lamp pole

The total cost of this set of components is about 10398 yuan.

II. 40 W Option Configuration II (with regulated power)

1. LVD lamp, single channel, 40W, 24V system.

2. Effective illumination on local day is calculated in 4 hours.

3. The daily discharge time is 10 hours (take 7:00 p.m. - 5:00 a.m. as an example) through the controller at night.

The power of LVD lamp can be adjusted in different periods to reduce the total power consumption. The actual discharge time is 7 hours per day.

Example 1: 100% power from 7 p.m. to 11 p.m. and 50% power from 11 p.m. to 5 a.m. Total: 7h)

(Example 2: 7:00-10:30 is 100%, 10:30-4:30 is 50%, 4:30-5:00 is 100%)

4. Satisfy 5 consecutive rainy days (plus 6 days of electricity used overnight before rainy days).

Current = 40W_24V

= 1.67 A

Calculated accumulator = 1.67A*7h*5+1 day

=1.67A*42h

= 70 AH

Reserve 20% capacity for battery charging and discharging, and the actual current of street lamp is over 2A (plus 20%).

Losses, including constant current sources, line losses, etc.

Actual battery demand = 70AH plus 20% reserved capacity plus 20% loss

70AH_80%*120%=105AH

The actual battery is 24V/105AH, which requires two groups of 12V batteries totally: 210AH.

Calculating the Battery Plate

1. LVD lamp 40W, current: 1.67A

2. Discharge time is 10 hours per day. After power regulation, the actual calculation is based on 7 hours (power regulation is the same as storage battery).

3. Reserve at least 20% of the batteries.

4. Local effective light is calculated with an average of 4 hours per day.

WP_17.4V=(1.67A*7h*120%) _4 H

WP = 61W

The actual constant current source loss, line loss and other comprehensive losses are about 20%.

Actual demand for battery panels = 61W * 120% = 73W

Actual batteries require 24V/73W, so two 12V batteries are needed: 146W.

Simple and practical: Solar street lamp configuration calculation method:

1:

Module power = load power * working time /(local sunshine coefficient * 0.85 * 0.8 * 0.8)

0.85: Redundancy factor of components 0.8: efficiency factor of storage battery 0.8: working efficiency of the whole system

The above coefficients can fluctuate slightly according to environmental conditions (dust, temperature, etc.) and product quality.

It can also be simplified as: component power = (load power * working time) / (local sunshine coefficient * 0.544)

Light source: 14W working hours 8 hours, rainy days 4 days, assuming local sunshine coefficient: 5 (hours)

System Voltage: 12V

(14*8)/(5*0.544)=41W module power available: 40W

2:

Battery capacity = working current * working time * (rainy days + 1)} / 0.8

+1: Add the previous night's number of days, 0.8: battery utilization factor

Working current: 14/12 = 1.2A

Battery capacity={1.2*8*(4+1)}/0.8=(1.2*8*5)/0.8=48/0.8=60ah

Battery capacity: 12V60ah

3:

Controller has limitation of working current: so it is enough to exceed the working current of the system.

Controller: 12V5A

However, the price of 5A and 10A of the controller is similar, but 10A is slightly more efficient, usually 12V10A.