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A properly installed 400W solar panel system can fully charge 1 x 200Ah batteries, 2 x 100 Ah batteries or 4 x 50Ah batteries connected in parallel (about 200 Ah total) in about 4-6 hours each day.
The charging time of 4 – 6 hours of a 200Ah battery bank with a 400W solar panel system is based on:
- the battery bank is discharged to only 50% of its capacity. If it is discharged more (bad for AGM batteries), they will take longer to fill
- the solar panels are installed in a location that receives about 5 hours of sunshine.
You will need more hours to charge the battery bank if it is installed in a location with fewer hours of sunshine.
The table below is an indicative guide of the number of batteries that you can connect to a 400W system for a location with 4-6 hours of sunshine.
|No||Battery capacity (Ah)||No. of batteries|
Note: The table above assumes AGM, Flooded, or Gel type batteries that have a recommended depth of discharge of 50%.
A 400W solar panel system can fully charge 1 x 100Ah Lithium battery daily in a system.
Lithium batteries can be discharged up to 80% without damaging them.
Recommended Battery Bank Size for a 400 Watt Solar System
To prevent the harvested energy from going to waste, the recommended battery bank size to use with a system this size should be 200Ah for AGM, Flooded of Gel type batteries.
If you are using lithium batteries, you can use 1 x 100Ah Lithium battery.
When you connect a larger battery bank larger than 200Ah, you run the risk of your solar panel system failing to fully charge it in a day which is bad for your battery bank in the long term.
Examples of Appliances to Connect to a 400 W Solar System
A 400W solar panel system can generate between 1,600-2,400 Wh of energy daily when installed in a location with 4-6 hours of sunshine.
Examples of appliances that a 400W solar system can run are:
- LED lights
- desktop computer(s)
- mini fridge
- microwave (700-900W)
- toaster (700-900W).
With larger appliances or if multiple appliances are connected, the battery run-time will reduce considerably.
Estimated Run-Times for Appliances Using a 400 Watt | 200 Ah Solar System:
- 40W Laptop, 28 hours
- 70W TV, 14 hours
- 130W fridge, 24hours assuming a 33% duty cycle
This assumes a system efficiency of 80% with a battery that has a depth of discharge of 50%.
To run AC appliances an inverter is required.
Inverter Size to Use with a 400 W Solar System
A suitable inverter size to use with this system is the 1,500W or 2,000W inverter. In addition to the solar panels, batteries, and inverters, include fuse protection against overcurrent and short-circuit faults.
Protecting a 400 W System from Faults: Fuse Protection
Typical fuse sizes used to protect against short-circuit and overcurrent faults with this system size are as follows:
- between panels and controller, 30A
- between controller and battery, 30A
- between inverter and battery, 150A
# 1. How Long it Takes a 400 W Solar Panel System to Fully Charge a Battery ?
A 400W solar system can fully charge a 200Ah battery in about 4-6 hours and a 100Ah battery in about 2-3 hours. If using a 50Ah battery (which will be a case of undersizing), the battery can be charged in about 1 hour.
Note: The above estimates assume a location that receives about 4-6 hours of sunshine and that the battery is only discharged to 50% of its capacity.