The only relationship between the number of solar panels installed and the battery capacity is that the charging current cannot exceed 10% of the battery capacity expressed in C10.
- For example, a charging current of 60A would be the maximum allowable value for a 600Ah battery in a C100.
1.The number of solar panels required.
The power of the photovoltaic field is designed to cover the daily consumption in the worst conditions of solar radiation. That is, if the solar kit usage is year-round, we will design the power of the PV field to cover the daily consumption of one day in December. If the solar kit will be used for vacations and weekends at other times of the year, we will design the power of the PV field to meet an average day in September or October.
The capacity of the battery indicates how autonomous the solar kit will be. Since we don’t want the battery to have more than 50% depth of discharge, we multiply the daily consumption by X2 so that the battery has twice the capacity of the day’s consumption. (This would mean 1 day of autonomy). After that, we multiply by the desired number of days of autonomy to get the total capacity of the battery.
Typically, batteries are designed to have 3-4 days of autonomy. This means we have to multiply our daily consumption by 6. (Multiply by 2 at 50% battery, 3 for 3 days of autonomy; 6 in total).
Example: Consumption 2000 watts/day x6 = 12,000 watts/day
If the battery is 12V: 12,000Wh / 12V = 1000Ah battery at 12V. (1 battery of 12V and 1000Ah; or 2 batteries of 6V and 1000Ah in series; or 6 batteries of 2V and 1000Ah in series)
If the battery is 24V: 12,000Wh/24V = 500Ah battery at 24V.( 2 batteries 12V and 500Ah batteries in series; or 4 6V and 500Ah batteries in series; or 12 2V and 500Ah batteries in series)
If the battery is 48v: 12,000Wh/48V=250Ah battery at 48V (consisting of the following. 4 batteries of 12V and 250Ah connected in series; or 8 batteries of 6V and 250Ah connected in series; or 24 batteries of 2V and 250Ah connected in series batteries connected in series)
* All batteries in the previous examples have the same power.
3. Power and working voltage of the inverter
For systems with necessary power less than 1000W, we can do solar installation at 12V.
For systems with necessary power between 1000W and 3000W, we will do solar installations at 24V.
For systems with necessary power greater than 3000W, we will do solar installations at 48V.