Assembling My Harbor Freight 45 Watt Solar Panel Kit - No Tools Needed!




Introduction: Assembling My Harbor Freight 45 Watt Solar Panel Kit - No Tools Needed!

I originally wanted to design my own solar panel controller then buy the "best deal" in solar panels out there I could find. While doing my research I kept coming back to the Harbor Freight 45 Watt solar panel kit because it looked like for less than $200 (at the time) the kit would do everything I wanted to do with solar power.

I found a lot of bashing on-line about these kits so I read through the BS and the three major complaints were:

The controller is simple and does not use PWM to charge the battery.

But it's a 45 watt system for less than $200. What do you expect for less than $200????

It's only 45 watts.

This is OK for me, I'm planning to just run a couple of lights and maybe a fan and none of these will be on for very long.

The controller that comes with this kit does not include a low voltage cut-off needed to protect the battery.

This is absolutely not true and I found the schematic on-line to prove it's not true. Then I took the cover off the controller to analyze the circuit myself to verify the schematic is correct. This controller does include a low voltage cut-off to protect your battery from over discharge.

The positive points were the kit seemed to have everything I need except for a battery and maybe a power inverter! Also, everything appeared simple to hook-up.

I wrote this instructable as a review of Harbor Freight's kit, but the real reason I bought the kit was to install solar lighting in my storage building. You can see the full install in this instructable.

Step 1: I Bought and Unpacked the Harbor Freight Kit

I finally had about $200 to spare and I bought the Harbor Freight kit. My first surprise was how heavy this kit was - it's almost 60 lbs!

Next I unpacked the solar panels - each solar panel was protected by a pair of styrofoam panels. I also discovered why the box weights so much. The solar panels are very heavy for their size.

The next surprise came when I unpacked the tubes that assemble into a frame. I expected some cheap thin PVC tubing. What was in the box was still plastic but the plastic was very heavy. Also, everything was clearly labeled.

The other major parts - the controller and light were packed in a box inside the main box and the interconnect wiring was in with the plastic frame parts.

Step 2: Assembling the Frame

The kit comes with two sets of screws & wing nuts. The shorter screws are used to assemble the frame. Everything goes together like the picture on the outside of box and like this instructable title says - no tools needed. You just drop the screws through the holes then tighten the wing nuts. A philips (cross tip) screw driver won't hurt if you want to snug everything down tight, but it's not absolutely necessary.

Step 3: The Working Parts of the Kit

Like the box says - everything's included except the battery and a power inverter (assuming you need one), but I don't need one because I'll be using the two 12VDC florescent lights included with the kit.

Step 4: Solar Panel Assembly

The solar panels themselves attach to the frame with the same style screws and wing nuts that are used to assemble the frame, only they are longer and include a small flat washer. The panels each attached with four screws, 2 on the top and 2 on the bottom.

The frame itself has two swing out legs and you set their angle with two of the screws left over from assembly. This makes it easy to set-up the panel, then take it down when not in use. If you like camping it would be easy to stow this somewhere in your Vanagon or camper then drag it out and set it up in just a few minutes. A philips (cross tip) screw driver won't hurt if you want to snug everything down tight, but it's not absolutely necessary.

Step 5: Wiring It All Up

Wiring is simple - it's all "plug and play".

The three solar panel cords plug into the 3 way adapter that comes with the kit and you can't plug the wires in reversed. Then the main cable plugs into the other side of the adapter.

The ring terminal end of the cable attaches to the solar panel side of the charge controller back panel. Everything's color coded and just like the first part there's "no tools required".

The battery charge cable attaches the same way.

I was concerned about cable length so I stretched the solar panel main cable down my driveway and measured the length. The longest tape measure I have is 25' but based on the length left over, it looks like the overall stretched-out length is 30'. This means you can park your camper or Vanagon in the shade and drag your solar panels out into the sunshine. Or if you are setting your solar panel up for emergency lights there is a good chance you can set the panel far enough away from the house to catch some light.

The two florescent light cords are pretty long too - 16 feet per my measuring tape.

Step 6: Connecting the Battery and Lights

The final step is connecting the battery. I went ahead and connected to a marine battery I had laying around and before I turned the controller on I disconnected the solar panel just to see what the voltage was. It's pretty low - 9.8 volts but it's also a very discharged battery

Next I connected the solar panel back up and the battery reached 12.8 volts pretty fast. This is a good sign for the solar cells - they are producing power. But it looks like I'll be replacing this battery because the voltage should not have come up this fast!

Once I had charged the battery for about an hour I tried the lights. They seem to work well.

Step 7: Technical Stuff - for Anyone Who Cares

I chased down the schematic for the Harbor Freight charger and it's pretty impressive for what it is.

The charger uses a comparator circuit and a reference voltage to switch the solar cells on and off. This is important because you don't want to over charge your battery.

The charger uses a second comparator circuit and the same voltage reference to disconnect your loads when the battery gets too low. This is just as important because discharging your battery too much will destroy your battery.

Step 8: Conclusion

It seems to me that this kit would be a great addition to anyone's camping gear. You should be able to run lights and maybe a small exhaust fan inside your camper.

You could also set one up for emergency lighting in case of a power loss. This happened to us a few years ago in North Alabama and I was fortunate enough to have a couple of gas lamps to light up the house.

But this Harbor Freight kit has some limitations. You won't be able to run a A/C unit or small refrigerator or freezer. These appliances need a power source much larger than this kit will provide.

So, what do you need to run a "typical" freezer in an emergency?

Per my deep freeze data plate it need 5 Amps and 5 Amps X 120 Volts is 600 Watts. Run this freezer for an hour a day and it will consume 600 Watt/Hours of power. I'm quoting an hour because I discovered that, at least with my freezer, an hour a day was enough to keep my food frozen and safe.

Assuming the Harbor Freight kit charged at full power for 10 hours / day, and it won't unless you live someplace like Arizona, it will only charge 450 Watt/Hours of power a day. This is far short of what I would need to run my deep freeze an hour a day. Your situation would be a little different based on the freezer you own, regardless this kit won't work.

So, what do you really need to keep your frozen food frozen in an emergency? I figure about a 300 - 400 Watt solar panel, a charge controller rated for your solar panel's wattage and enough batteries to store that energy will do. A "off grid" solar panel kit from Home Depot will cost you about $1400 and you have not bought the batteries yet. A generator is cheaper.

I wrote this instructable as a review of Harbor Freight's kit, but the real reason I bought the kit was to install solar lighting in my storage building. You can see the full install in this instructable.



  • Creative Misuse Contest

    Creative Misuse Contest
  • Metalworking Contest

    Metalworking Contest
  • Water Contest

    Water Contest

20 Discussions

I am looking for a power source for a couple overhead bulbs (intermittant), and garden lights (on timer). My front yard doesnt get much light to charge individual solar lamps. Would you recommend this kit? Anyone recommend something else?

1 reply

Yes, if you can place the panels where they will receive a decent amount of light. Also, HFT's latest version of this kit is rated at 100 Watts - that's quite an improvement over the kit I based this article on! Tom

Thanks so much for making this Instructable. I bought this same kit and an inverter from Harbor Freight to take camping. Your Instructable not only helps with the setup, it does a good job of putting everything into perspective, giving me an idea of what I can expect to get from this kit.

I'd like to take advantage of your knowledge, since it seems you know a lot about this topic and ask you some questions: Could I use a multi-battery setup with this kit for longer lasting power? If so, how many batteries do you think this kit could support? I've seen were people have used multiple batteries to power their house and I am considering doing something like this possibly someday and am curious if this kit could be used toward the start of doing something like this.

Thank you in advance for any help or information you can provide!

2 replies

You should be able to use a larger battery for one of these solar panel kits, but "how large" I don't know. This is because the real limitation is the total amount the solar panels can charge your battery between uses and how much energy you use between charges. But even if you pull more from your battery than you charge, a larger battery might still be to your advantage. For example, you could leave home with a fully charged marine battery and bump the charge every day with the solar panels, extending you usage a couple of days. Tom

single 100 watt panel 5 amps $120 home depot vs 45 watt 1.9 amp for $200

1 reply

You are absolutely correct for a permanent install, but the HF kit is portable and would be great for camping or as temporary lighting and as a cell phone charge station during a power outage.

Thanks for the review. I just bought a Lifetime plastic shed and this harbor Frieght solar kit would be perfect for my needs.

Excellent write up on this Tom! I recently bought one for $139 with the coupon. Looking forward to trying it out.

2 replies

Recent coupon from Harbor Freight was for $139. I subscribe to them and get emails with the latest sales and coupons.

I like harbor freight soon course I think this is cool. Great work!

If you bought one of the "extra" panels from harbor freight to go along with this kit, how would it hook up? Can you simply add panels to this controller? Or, would I even need to? Would I only need to add panels if I had more batteries to charge?

1 reply

The adapter cable is setup to take only three solar panels but you can use one if these to add more.

But you have to be careful - the controller is rated for 3 Amps which is in theory what the three panels are rated at. This means that if you add the 4th panel and they really do put out 100%, or 4 amps, then the thermal fuse on the back of the charge controller will disconnect the panel then reconnect them over & over again. You can replace the thermal fuse with a higher rated one and add another diode if you know how to solder.

Or if you don't know how to solder you need one of these in addition to the 8 panel box.

There does not appear to be a low battery voltage disconnect. I find this to be a real issue with this system. Any idea on the prices on individual panels?

2 replies

The controller has an internal low voltage battery disconnect built-in and I mentioned this in step 7 of the instructable. Harbor Freight sells the individual panels for about $70 each. It's cheaper to buy the kit I bought if you want three panels.

I looked at the schematic on a computer instead of a phone - I see the battery disconnect is via Q6, disconnecting the ground to the battery.

Thanks for the instructable! I have been debating on buying the kit, and your instructable is biasing me towards the purchase!

I liked that you added the additional info regarding the pros and cons of the set. Great info.

I'm curious about storability and portability of this kit, how heavy would you say it is? there are twenty dollar briefcase solar panels at bi-mart sometimes, 5 watts each I think. would you recommend saving up for this, or buying them individually when I have the money to do so? I don't know if they have charge controllers.

1 reply

The three panels attached to the frame probably weigh 45 - 50 pounds. I don't have an issue with the weight but you might depending on what you can carry. If weight is an issue then you can disassemble the solar panels from the frame and put them up separately, it will just take longer to set back up.

5 watt solar panels are a waste of time for anything but a charger to keep a battery charged. Even a modern cell phone will take more than 5 watts of power to charge.