How Do Solar Panels And Their Battery Backup Systems Work?
September 14th, 2009
I’m looking at a need of roughly 130w/hour need per 24 hour period. I’ve spent several hours now looking for information on the web and have found plenty of info regarding the panels themselves, but information regarding the batteries backups have been trim. I comprehend that there’s a 5-7 hour “peak” time to collect the energy. I’m looking for information regarding the batteries themselves. How do the batteries work, what size batteries should I look for, and what’s the life expectency for the batteries? Any website links would also be appreciated!
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Solar panels have their own characteristics and generate current depending on the intensity of sunlight falling on them and not on the temperature. Direction of the panel also makes lots of difference. Nowadays very thin panels are available at very high cost. The more area a panel occupies it generates more current.
The current generated by a panel cannot be readily used since the current and voltage varies with the load connected to it. So normally a regulator is used to have constant voltage and constant current to come from the panel. This charges the battery.
You have to calculate the total/normal current from the charger and then find the AH of the battery. When you have calculated the AH of the panel/charger then you can divide the AH of the battery by the AH of the charger/panel and find out the time taken to fully charge the battery. You also have to remember that there is a de-rating factor to be taken into consideration in the battery.
First, you didn’t say the voltage.
Second, 130 W/hour per day.
Third, battery backup capacity in Ah = Ampere hour.
For 12 Volt DC here’s the calculations :
130 w/hour means = 10.83 or rounded 11 Ampere hour.
You know peak time 5-7 hour (let say 6 hour)charging time (collect the sun energy).
11 Ampere hour per day (24 hour), with 20 Ah Battery backup is OK.
And the Solar Panel is 3 Ampere charging capacity minimal = 3 Amp x 6 hour = 18 Amp hour.