I often get the question if you can connect a PWM or MPPT charge controller directly to an inverter.
Unfortunately, the answer is no.
Why can’t you connect an MPPT directly to an inverter?
A charge controller, whether it be a PWM or MPPT charges the battery based on internal resistance.
If a battery is depleted, the internal resistance is low. When a battery is full, the internal resistance is high.
If you connect a charge controller directly to an inverter, the internal resistance would be at its highest, meaning that it senses that the battery is full. Thus it will not deliver power to the inverter.
What is the correct way to connect an MPPT to an inverter?
You need three things:
- Charge controller
- Battery
- Inverter
First, you need to connect the battery to the charge controller. This is essential to set up the charge controller. You will most likely have a charge controller that detects the voltage of the battery automatically. Next, you need to set the type of battery. Read my articles about the best PWM and the best MPPT charge controller to see which charge controllers are compatible with lithium.
Next, you need to wire from the battery terminals or busbar to the inverter. Don’t forget to add a fuse. Read my article on how to calculate a fuse. Next, decide the gauge of your wire. This is going to be the thickest wire in your system so keep it as short as possible. Read my article about how to select wire gauge.
After that, you can connect your solar panels to the charge controller.
If you want to read more in-depth about this method of connecting the solar panels to an inverter, read my article here: how to connect a solar panel to a battery
Conclusion
You cannot connect a PWM or MPPT directly to an inverter. You need a battery in between these two in order for it to work. You can have a small battery as well just as a reference. If your load is small, you can get away with a small battery. Watch my video about c-rate here to find which capacity you need.
I guarantee this guide will save you $100s on buying the right components by having a good design and sizing.
You can get the book for a reasonable price on amazon
I’m an off-grid enthusiast. I created this website to give clear and straight-to-the-point advice about solar power. I’m also the author of the book ‘Off-grid solar power simplified‘. Read more about me on my about page, check out my Youtube channel, or send me a message.
Thanks nick. kindly can I connect my two 12v 75ah to get 24v 150ah. Leonard.
Yes, connect them in series. Make sure they are fully charged or discharged before connecting.
2x 12v 75Ah batteries in series = 24v @75Ah
2x 12v 75Ah batteries in paral = 12v @ 150Ah
I thought connecting battery’s in series increased the voltage but the current stays the same. Conversely connecting in parallel the current increases but the voltage stays constant.
Correct me if I’m wrong.
Correct. But you are confusing current with capacity. The capacity stays the same in parallel, not the current.
Hi!
I have currently connected the inverter to my MPPT using the Load terminal. The MPPT can output 20A and I’m planning to only use around 150w from the 220v output of the inverter. Is this safe ?
I don’t recommend that. You better wire the inverter straight to the battery. If the inverter is larger than 150W, then it’s ok. if it’s a 1,000W inverter, then it can draw inrush current and the output on the MPPT can get damaged.
i want to connect a 585 watt 2 solar panels and MPPT controller to 110 battery and a mini inverter 1500 watt can i run a air cooler of 350 watt and 4 ceiling fans
Take a look at my solar system design video.