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How many solar panels do you need to charge a 48v battery? There are many different options for charging your batteries. Let’s explore the options before you make any decisions about how much power you need!
As a general rule, the number of solar panels needed to charge a 48v battery can be calculated by dividing the watt/hours capacity of the battery by the average hours of sunshine per day and then dividing that number by the solar panel wattage.
For example:
If you have a 3.6 Kw/hour lithium-ion battery and you receive on average 5 hours of sunshine per day:
3.6 kW/hour = 3600 watt/hour
3600 watt/hour divided by 5 hours = 720 watts.
Your solar panels will thus have to produce 720 watts of power in total.
If you plan on installing 250-watt panels, then you will need :
720/250 = 2.88 solar panels.
You will thus need a minimum of three 250 watt panels to charge your 48v battery.
Amount of solar panels needed per battery size
| 250-watt Solar Panels (Nr) | 48v Battery Size |
|---|---|
| 2 | 2.4kWh |
| 3 | 3.5kWh |
| 4 | 4.8kWh |
| 11 | 13.5kWh |
The estimates above are the minimum amount of solar panels needed to charge a 48v battery with 5 hours of sunshine per day. If you are in an area with more sunshine, then you will need fewer solar panels because the wattage needed is lower due to how much sunlight that location receives on average each day.
What if you want to charge the batteries and use power as well?
If you want to charge your batteries and use some solar power, then the calculation above is how many solar panels you need for the battery only. You will need extra solar panels to cover your energy needs if you plan to power some of your appliances with the power produced by your solar panels.
Determine your daily energy usage
The first step will be to determine your power usage by adding up how much energy you use in a day. You will need to calculate how many watts of power are needed for each appliance or device that uses electricity.
For example, how many watts does a refrigerator use? Let’s say it is 700 watts in 24 hours. You will also need to calculate how much power your lights use. It is 100 watts for 6 hours, which will give you 600 watts/hours. You will need to do that for every appliance that you will be using in your home.
In our example:
Refrigerator : 700 watt/hour
Light: 600 watt/hour
Total = 1300 watt/hour = 1.3 kWh
You will thus be using 1.3 kWh of electricity and will need to add extra solar panels if you want to power the appliances.
Determine the extra solar panels needed
Using the same battery as in our example above, our total energy requirement will thus be 3.6KWh + 1.3kWH = 4.9kWh
4900 watt/hours divided by 5 hours = 980 watts = 4 x 250 watt solar panels.
You will basically need one extra solar panel to cover the energy needs in our example.
How long does it take to charge a 48v battery?
Most solar panels take about 10-12 hours to charge your battery, but the exact time will vary depending on the type of battery. Generally, batteries take less than 1 day to charge when there is enough sunlight available fully.
The first factor determining how fast your batteries charge is the amount of sunlight they will be exposed to. A 400W solar panel would produce around 340 watts in an hour during the middle of the day. A 48V, 9.6kWh battery will need 9600 watts to fully charge from 0% SOC (state of charge).
It should be noted that a 200AH lead-acid battery should never be discharged to 0% SOC as it will damage the battery. 50 % would be the maximum, and it will be better for the battery’s longevity to use less.
It would be best never to charge a battery faster than its C rating (200Ah / 5 = 40amps). The C rating is the manufacturer’s recommendation at which rate the battery should be charged or discharged.
This means you cannot try to pump a maximum of 200 amps of charge into the battery in an hour no matter how much sun you have because it will overcharge.
If you charge at 40amps / hour, it will take 5 hours to charge the 200AH battery. A charge controller can help regulate how much power the solar panels are providing and how fast you can charge your battery.
How many solar panels do I need to charge a 48v 200AH battery?
During the middle of the day, a 400W solar panel would generate approximately 340 watts per hour. A 48V, 9.6kWh battery will require 9600 watts to fully charge from 0 percent SOC (state of charge). If you plan on recovering at 50% SOC, it will take 4800W. You need to divide the number of watts required (4800W) by the number of watts available (340W) per solar panel, which equals about 14 panels.
Can you charge a 48v battery with a 12v solar panel?
No. A 12v solar panel can’t generate enough power to fully charge even a small battery. A 48v battery can be charged with a voltage as low as 24 volts. A third option would be to connect three 12v solar panels in series to charge a 48v battery.
