Thursday, September 21, 2023


Solar controllers vs. solar inverters

Solar charge controllers (solar regulators) were once the only option for off-grid power systems and are used to create what is known as a DC-coupled system. DC-coupled systems use solar controllers to charge a battery directly from the panels, which is extremely efficient, while a battery inverter supplies AC power to home appliances.

AC (alternating current) coupled solar

AC-coupled systems use a string solar inverter coupled with an advanced multi-mode inverter or inverter/charger to manage the battery and grid/generator. Although relatively simple to set up and very powerful, they are slightly less efficient (90-94%) at charging a battery compared to DC-coupled systems (98%). However, these systems are very efficient at powering high AC loads during the day and some can be expanded with multiple solar inverters to form micro-grids.


  • Higher efficiency when used to power AC appliances during the day such as air-conditioning, pool pumps, and hot water systems (up to 96%)
  • Generally lower installation cost for larger systems above 5kW
  • Can use multiple string solar inverters in multiple locations (AC couple micro-grids)
  • Most string solar inverters above 3kW have dual MPPT inputs, so strings of panels can be installed at different orientations and tilt angles
  • Advanced AC-coupled systems can use a combination of AC and DC coupling. (Note: this is not possible with some lithium batteries.)


  • Lower efficiency when charging a battery system (approx. 92%)
  • Quality solar inverters can be expensive for small systems
  • Lower efficiency when powering direct DC loads during the day

DC (direct current) coupled solar

DC-coupled systems have been used for decades in off-grid solar installations and small-capacity automotive/boating power systems. The most common DC-coupled systems use solar charge controllers (also known as solar regulators) to charge a battery directly from solar, plus a battery inverter to supply AC power to household appliances.


  • Very high efficiency
  • Great low-cost setup for smaller-scale off-grid systems up to 5kW
  • Ideal for small systems requiring only 1-2 solar panels
  • Modular (additional panels and controllers can be easily added, if required)
  • Very efficient for powering DC appliances and loads
  • If an electricity service provider restricts or limits the capacity of grid-tie solar allowed, additional solar may be added by DC-coupling a battery system


  • More complex to set up systems above 5kW, as often multiple strings are required in parallel, plus string fusing
  • Can become expensive for systems above 5kW as multiple higher voltage solar charge controllers are required
  • Slightly lower efficiency in powering large AC loads during the day due to the conversion from DC(PV) to DC(batt) to AC
  • Many solar controllers are not compatible with managed lithium battery systems such as the LG Chem RESU or BYD B-Box

RV Electricity Converter vs Inverter



Dustin Simpson
Dustin Simpson
I have worn many hats in the RV industry through the years. From an RV Technician, Warranty Administrator, Parts Administrator, Parts Manager, Service Manager and now Business Owner. I have even been deemed an RV Expert by the California court system, working on behalf of the customers, dealers, and manufacturers. My repair facility has been servicing customers at the same location since 2003. What sets us apart from the dealerships is we are here to fix and maintain what you have, and not sell you a new one. Whether you own a million-dollar unit or an entry level, my message to you will be the same, it needs to be maintained.



Please enter your comment!
Please enter your name here

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Sign up for the

RVtravel Newsletter

Sign up and receive 3 FREE RV Checklists: Set-Up, Take-Down and Packing List.