Solar panel arrays can be seen everywhere these days. Just outside my office workers are finishing the installation of a large solar array on top of a new parking garage here at Analog Devices’ Wilmington campus. In my neighborhood I see several homes upon which solar panels have been installed in just the past few years. I’ll bet there are a few in your neighborhood, too. The only problem with solar panels is they need sunlight to generate electricity, rendering them non-producing at night and on cloudy days. That is why the output from most solar arrays are used to charge banks of batteries.
The 100 kW solar array being installed at ADI’s Wilmington campus
A circuit is needed between the output of the solar array and the input to the batteries to manage the efficient and safe flow of energy. This is where one could find a new product from Analog Devices, the LT8491 High Voltage Buck-Boost Battery Charge Controller with Maximum Power Point Tracking (MPPT) and I2C Interface. It’s a small part with a long name, but with all its rich features the LT8491 can be an invaluable part of systems for maximizing the efficiency of any size solar array. Let’s look at each of them:
As the efficiency and power output of solar panels continue to improve, there is a growing need for charge controllers supporting higher voltages. Unlike existing solutions (which max out at 30 volts) both the input and output voltage range of the LT8491 is up to 80 volts, providing more flexibility to system designers seeking to maximize array outputs.
Buck-Boost Battery Charge Controller
Let’s say you are using your solar panels to charge numerous 12-volt batteries (a lot of folks do this because automobile batteries are easy to get and not expensive). It is a sunny day and your panels are doing their job creating electricity when the sun dips behind a few cirrus clouds, not quite cutting off all the light but reducing it, and the output of the array drops to 8 volts which is not enough to charge the batteries. This is when the Buck Boost Charge Controller in the LT8491 goes to work, bringing the voltage back up to 12 volts. The opposite is also true. Should voltage from the array in our example rise above 12 volts the LT8491 automatically reduces (or bucks it) back down to 12 volts, preventing damage to the batteries in the bank. Only Analog Devices has both Buck and Boost in a single chip, saving space and power consumption for the system designer.
Maximum Power Point Tracking (MPPT)
Weather changes directly affect the solar panel output power. For example, typical solar panel output power will drop under partial shade conditions when clouds pass over in front of the sun. LT8491 on-chip logic provides automatic true power point tracking (MPPT) for solar powered applications. It performs periodic scans of the solar panel to extract maximum level of power, even under partial shade conditions and deliver it to the battery.
The LT8491 includes a built-in I2C digital interface giving users the ability to monitor real time charger telemetry data, including any fault conditions. It also provides users the ability to change the charge algorithm which allows the charger to support charging of many different battery types, including sealed lead-acid (SLA), flooded, gel and lithium-ion.
With more governments, companies, and homeowners seeking to feed their power needs with solar energy, the LT8491 will enable designers to build arrays producing higher voltages, translating into more reserve power in the batteries. More details on features and performance of the LT8491, as well as even more information how this Buck-Boost controller can maximize the performance of your solar array system are available on its product age here.