Harbor Freight 100W Solar Kit. Full Review – Day 1


Introduction to the Harbor Freight 100W Solar Kit

The Harbor Freight 100W solar panel kit was released in late June or early July 2017. I have just unboxed it and laid out all the components. Currently, nothing is permanently mounted or connected. This review captures my first impressions and observations.


Unboxing the Kit

Harbor Freight 100W Solar KitUnder the evening sun in my backyard, I took a closer look at the contents of the box. Here’s what the kit includes:

  • Solar Panel Controller: Manages the input and output of the solar panels.
  • Battery Connector: Hooks the panels to the battery.
  • Proprietary Front Panel Connection: Used for the solar panel input to the controller.
  • Combiner: Combines the inputs from multiple panels.
  • Lights with Switch: Practical lights provided by Harbor Freight.
  • Manual: Guide for setup and operation.
  • Mounting Hardware: Necessary tools and accessories to mount the panels together.


Cable Lengths and Setup

One of the first things I wanted to know was the length of the cables provided. Using a tape measure, I found:

  • Combiner Wire: The main wire for the solar panels measures about 12 feet.
  • Light Bulb Cable: This cable extends to around 15 feet, which is quite convenient for setting up the lights at a distance from the power source.


Panel Details

Each solar panel in the kit has a metal bracket that allows it to stand upright. Additionally, each panel is equipped with a six-foot power cable. The panels are serialized, meaning each one has a unique serial number. I found that all four panels included in the kit had matching serial numbers. Another useful feature is the indicator on each panel that shows when solar energy is being captured.


Comparison with Older Kits

new 100W solar panel kit

The new 100W solar panel kit has several improvements over older versions:

  • Increased Wattage: The old kits had panels rated at 15 watts each, with a total of three panels amounting to 45 watts. The new kit includes four panels, each rated at 25 watts, resulting in a total of 100 watts.
  • Updated Controller: The controller in the new kit is smaller and more modern compared to the older version. It also has more features and is easier to use.


Controller Features

The controller included in the kit has several input and output options:

  • Solar Input: This is where you plug in the solar panels.
  • Battery Connection: This port connects to the battery to charge it.
  • Standard DC Outputs: These outputs are for various DC-powered devices.
  • USB Power Out: This port allows you to charge USB devices, though the amperage is not specified in the documentation.


Initial Testing and Observations

To test the kit, I connected a Harbor Freight 35 amp-hour battery to the charge controller. The controller displayed a reading of 12.8 volts. For comparison, I used a multimeter, which showed a slightly higher reading of 13.08 volts. The kit’s clamps, which connect to the battery, felt somewhat cheap and flimsy. While they are likely sufficient for the job, they do not inspire much confidence.


Voltage Reading Discrepancies

During my initial tests, I noticed a slight discrepancy between the voltage readings from the charge controller and the multimeter. The difference was minor and likely not a significant issue, but it’s something to be aware of.


Evening Solar Panel Performance

Even as the sun was setting and the panels were not directly facing the sun, they still managed to generate some power. The battery voltage increased slightly, indicating that the panels were effectively charging the battery even in less-than-ideal conditions.


Menu Navigation

Navigating the controller’s menu is straightforward, but I need more practice to fully understand each option. The manual provides useful guidance on this, but a bit of hands-on experience will be necessary to become completely comfortable with the system.


All Harbor Freight Setup

For this test, I aimed to use Harbor Freight products exclusively. This included the battery, screwdriver, and multimeter. While the free multimeter from Harbor Freight felt a bit unreliable, the other equipment performed adequately.


Overnight Testing Plan

I plan to leave the panels out overnight to see how they perform over an extended period. In the morning, I will check the charging performance and see how much power the panels have generated.



Overall, my first impressions of the Harbor Freight 100W solar kit are positive. It is a significant upgrade from the older 45W kit, offering better power output and a more modern charge controller. The price of $150, especially with a coupon, makes it a worthwhile investment. I will continue testing and provide further updates based on my observations.


Detailed Review and Testing Process

Setup and Initial Impressions

Upon opening the box, I was greeted with a well-organized set of components. The first task was to lay out all the parts and get a sense of what was included. The solar panel controller looked sleek and modern, a big improvement over the older, bulkier versions.


Connecting the Components

Connecting the various components was straightforward. The connectors and cables all fit together easily. The proprietary front panel connection for the solar panel input to the controller was particularly user-friendly. Once everything was connected, I moved on to testing the system.


Testing the Voltage

Using the Harbor Freight 35 amp-hour battery, I connected it to the charge controller. The initial reading on the controller was 12.8 volts. To verify this, I used a multimeter, which showed a slightly higher reading of 13.08 volts. This discrepancy, while minor, is something to note. The clamps provided in the kit felt a bit flimsy, but they worked well enough for the test.


Solar Panel Performance in Low Light

One of the more impressive aspects of the kit was its performance in low light conditions. Even with the sun setting and the panels not directly facing the sun, they still managed to generate enough power to show an increase in battery voltage. This suggests that the panels are quite efficient.


Understanding the Controller

The solar panel controller has several menus that provide different information. Cycling through these menus was easy, though understanding what each one meant took some time. The manual was helpful in explaining the different options and settings.


Practical Testing

To further test the system, I left the panels connected overnight. The following morning, I checked the battery to see how much it had charged. The results were promising, indicating that the panels could generate a decent amount of power even with limited sunlight.


Future Plans

My next steps will involve mounting the panels permanently and conducting more long-term tests. I am particularly interested in seeing how well the system performs under different weather conditions and with various loads connected to it.


Final Thoughts

The Harbor Freight 100W solar kit is a solid investment for anyone looking to harness solar energy. It offers significant improvements over older models and provides good value for the price. The setup is user-friendly, and the components are generally of good quality. I look forward to further testing and will provide updates as I continue to use the system.