500 watt Solar System | What Charge Controller, No. of batteries, Inverter size to Use?

Perhaps you considering a power solution for your RV, boar or off grid cabin, a 500 watt solar system can be a good and effective way to start keep your appliances running.

With the available 1,500 – 2,500 Wh of daily energy possible, depending on your location and how many sunshine hours it receives, the 500 watt solar panel can supply several hours of power to appropriately selected connected appliances.

If the system does not come in a kit form then you’ll need to figure out what size of solar charge controller, capacity and number of batteries, and inverter rating.

Sizing the components correctly helps to get your appliances to run for many hours without worrying about your system running out of power or your system failing prematurely.

So, read on for guidance on what size of the charge controller to use, how many batteries to connect, inverter size to use, and what appliances you can connect to a 500 watt solar system

Charge Controller Size for a 500 Watt Solar System

You can use a 40A PWM or MMPT (preferably) controller for your 500 watt solar system. If you plan to increase the size of the solar system, then go for ( 60A+ charge controller).

Always confirm that the charge controller can handle the total voltage of connected solar panels to prevent damage.

Portable Solar Panel
Portable Solar Panel

Using a higher current rated charge controller though advantageous if you plan to increase the size of your system has the potential downside of not using the full capacity of your charge controller which costs higher if you have no plans to scale the solar system.

How Many Amps Does a 500 watt Solar System produce?

A 500 watt solar system can supply a maximum charging current of about 30 amps.

The actual current generated depends on how the solar panels are connected.

Related Posts: How many watts of solar can a 40A charge controller handle?

500 Watt Solar System: How Many Batteries Should you Use (Suggested Battery size Combinations)?

Note: This is an approximation, it is possible to use other battery combinations. This assumes about 3 hours of sunshine for your location.

If you receive more than 3 hours of sunshine at your location, you can use a larger battery bank.

You can use 2 pcs of 150 Ah or 200 Ah AGM or GEL batteries in parallel (12V) or 2 pcs of 75 Ah or 100 Ah Lithium batteries in parallel for a 12V battery bank.

This assumes a 250 Ah battery bank for a 12V system.

For a 24V battery system, you can use 4 pcs of 150 Ah AGM or GEL batteries (2 strings of 2 batteries in parallel) or 4 pcs of 75 Ah Lithium batteries (2 strings of 2 batteries in parallel).

This assumes a 125 Ah battery bank for this 24V system.

This is based on an estimated daily energy production of 1.5 kWh (about 3 – 4 hours of sunshine).


Battery capacity (Ah) = Average daily energy production (Ah) / (battery bank voltage x battery depth of discharge).

For a GEL or AGM, recommended depth of discharge is 50%, therefore battery capacity is 250Ah at 12V from1,500wh /(12V x 50%) and 125Ah at 24V.

Using smaller battery banks

If you use smaller battery capacities like a 50Ah, you underutilize the system because you are not able to store all of the electrical energy generated by the solar panels

Using larger battery banks

If you use considerably more batteries (larger battery capacity), there is a good chance that the generated power will not be enough to fully charge the drained batteries which affects their lifespan.

Related posts: How much energy does a 200 watt solar panel produce?

What Size of Inverter to Use with a 500 watt Solar System?

The inverter size largely depends on the combined capacity (w) of the appliances you plan to connect to.

That said it is common to find 500 watt solar system kits packaged with inverter sizes of capacities ranging from 1,000 – 3000 watts.

Smaller inverter sizes may be used but the size and number of appliances you can use with the available energy in the batteries is limited by their low maximum power handling capacity.

What Will an 500 Watt Solar System Run?

Some examples of common appliances that you can connect to a 500 watt solar system are shown in the table below.

Note: The list is not exhaustive and it is quite likely that there are appliances not on the list that can be used on a 500 watt solar system.

mini Fridge or freezer50 watt LED TV
Laptops or Desktop computerLED lighting
small pumpssmall power tools

How long the appliances run for depends on the state of charge of the battery, the battery capacity, and the total power consumption of connected appliances.

If the 500 watt solar panel system on a given day generates 1,500 Wh generated by the solar panels, you can comfortably run as an example:

  • Laptop: 40w laptop for 4 hours =160 wh
  • Lights: 5pcs each 10w for 6 hours = 300 wh
  • Fridge: 250W fridge for 4 hours =1,000 wh

Total 1,460 watt-hours which is within the available 1,500wh (assuming 3 hours of sunshine daily) supplied by the solar panels and stored in the batteries.

Final Word

A 500 watt solar system typically generates between 1,500 – 2,500 Wh of energy daily depending on the amount of sunshine available.

To store the generated energy, you can use 2 pcs of 150 Ah or 200 Ah AGM or GEL batteries in parallel (12V) or 2 pcs of 75 Ah or 100 Ah Lithium batteries in parallel for a 12V battery bank.

To control the charging process can use a 40A, 60 A, or higher current rated charge controller with the solar system if you plan to increase the size of the system.

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