If you need to power your home appliances or other appliances while on the go – in the boat or RV then depending on the combined power draw of these appliances and how many hours of sunshine your location receives, a 500-watt solar system may just be what you need!
Using it to its full potential though requires that you select the right component sizes – the right number and capacity of batteries, charge controller, and even connect the solar panels the right way.
So, in the case of a 500-watt solar panel system, how many batteries should you connect? What about their capacities?
Read on for the optimum number and capacity of batteries to use with the 500-watt solar, and what size of charge controller and inverter to connect.
How Many Batteries to Use (Suggested Battery Combinations)?
Well, there is no one right number of batteries to connect to your system.
The right number of batteries mainly depends on:
- the power consumption of connected appliances, – larger draw appliances require more capacity and potentially more batteries
- which battery types (LiFeP04/AGM) you plan to use, (AGM batteries have a lower usable capacity of ~50% and so you need more of them), and
- the duration for which you plan to run the appliances – longer runtimes require more capacity and can potentially result in more batteries
As a guide though, for a 12V system, you may connect 2 x 100Ah LiFeP04 batteries connected in parallel, or 2 x 200Ah AGM/Gel batteries connected in parallel.
For a 24V system, you may connect 2 x 100Ah LiFeP04 batteries in series, or 2 x 200Ah AGM/Gel batteries in series.
**This assumes a minimum of 4 hours of sunshine daily at the installation location and that the batteries are regularly discharged to their recommended depths of discharge – 50% for AGM and 80% for LiFeP04.**
Note: These battery selections are only intended as a guide.
What Size of Charge Controller (amps) to Use?
You can use a 40 amp MPPT (preferably) controller or larger a 500-watt solar system.
Unlike a PWM controller, an MPPT controller has more efficiency and stores more of the available energy in the battery.
How Many Amps from a 500-watt Solar System?
The estimated amps from a 500-watt solar panel system at peak is about 27.5 amps.
The number of amps depends on the rating of the solar panels and whether the solar panels are connected in series or parallel.
Connecting 5 x 100w solar panels in parallel, assuming each solar panel has an amp rating of 5.5 amps results in about 27.5 amps (5.5 amps x 5) at peak.
Why this Matters
Make sure you do not exceed the maximum amp rating of the charge controller to avoid damaging it!
How Many Volts from a 500-Watt Solar Panel System?
The estimated voltage from a 500-watt solar panel system at peak is about 90 volts.
The number of volts depends on the rating of the solar panels and whether the solar panels are connected in series or parallel.
Connecting 5 x 100w solar panels in parallel, assuming each solar panel has a voltage rating of 18 volts results in about 90 volts (18 volts x 5) at peak.
For an MPPT controller, aim to connect the solar panels in series within the maximum voltage the charge controller can handle for it to operate as efficiently as possible.
Why this Matters
Make sure your charge controller can handle the peak voltage rating of 90 volts to avoid damaging it!
Related Posts: How many watts of solar can a 40A charge controller handle?
What Size of Inverter to Use?
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.
Make sure its voltage rating (12V or 24V matches that of the battery bank) to avoid damage.
For example, connecting a 12V/2000-watt inverter to a 24V battery bank will damage it!
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 Appliances can you Run?
You can see examples of appliances that you can connect to a 500-watt solar system below. Note: The list is not exhaustive.
| mini Fridge or freezer | 50-watt LED TV |
| Laptops or Desktop computer | LED lighting |
| small pumps | small power tools |
How long the appliances run 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 2,000 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 2,000wh (assuming 4 hours of sunshine daily) supplied by the solar panels and stored in the batteries.
Final Word
A 500-watt solar system typically generates about 2,000 Wh of energy daily depending on the amount of sunshine available.
To store the generated energy, as a guide though, for a 12V system, you may connect 2 x 100Ah LiFeP04 batteries connected in parallel, or 2 x 200Ah AGM/Gel batteries connected in parallel.
For a 24V system, you may connect 2 x 100Ah LiFeP04 batteries in series, or 2 x 200Ah AGM/Gel batteries in series.
Use a 40A MPPT charge controller or larger with the solar system.
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