Adding a Harbor Freight 45 Watt Solar Panel to My Storage Building




Earlier this year we bought a 10' X 20" storage building and had it delivered to the backyard. The storage building is great - I'm slowly moving things from my garage to the building, I'm doing this slowly because at the end of the day I don't want everything thrown in the building - I want some organization.

One problem with the building is long before it gets completely dark outside it's so dark inside that I can't see anything. It's cost prohibitive to run power to the building so I decided to do the next best thing - solar powered lighting. For an application like this you really don't need a lot - you need to collect enough solar energy to turn on the lights maybe 15 minutes when you need them? But you also need enough energy to carry over cloudy days.

Also, my direct view of the sun is limited from the roof of my storage building by trees so I figure I'll get an hour or two of good strong sunlight a day. This meant that I probably could not get away with a small 15 watt solar panel.

I ended up buying a Harbor Freight 45 Watt solar panel kit and you can find my full write-up of this kit in this instructable.

Step 1: Install the Solar Panels

Installing the solar panels is pretty straight foreword. Because of the type of roof on my building I could just mount the panels with some outdoor rated screws. I was careful to mount one side of the panel through one of the ridges of the roofing and this placed the other side of the panel just inside a ridge.

Before anyone comments about the mounting angle I already know that these are not mounted at the ideal mounting angle for solar energy. But I'm not concerned about harvesting the maximum energy from the sun, I'm just using solar energy to light the inside of my storage building.

Step 2: Getting Power Inside the Building

To get power inside the building I drilled a couple of holes under the eaves then I fished the wires through. I'll pick up some silicone calk for the holes the next time I'm at LOWES.

Step 3: Hanging the Lights

This kit came with a couple of nice 5 Watt florescent lights, each with its own 16 foot power cable and switch. I'll wire both to a switch near the door but for now I'll use the in-line switches that came with the lights to turn them on & off.

I mounted one in each end of my building.

I used plastic staples to hang the wiring, available just about anywhere that carries minimal wiring supplies - I bought this pack at Wally-World for less than $2.00.

Step 4: Final Wiring

For final wiring I cleared off some shelf space for the controller and battery then I ran all the wiring to the controller.

I could have placed the battery on the shelf behind the controller but I wanted the battery out front so that I could easily remove the cell caps and check the electrolyte (water) levels.

In the last picture you can see the two black switches for the two florescent lights.

Step 5: End Result

You can see the solar cells mounted to the roof of my building.I'll know tomorrow after a full day's charging how well the lights work. But I suspect that my old marine battery is too far gone and I'll need to replace it.

If I decided to get really crazy with solar power I could mount 10 more panels to this side of my roof for a total of 195 watts!!! But what would I use it for?

You can find my full write-up of the solar panel kit I installed in this instructable.

Step 6: 09/09/2014 Update

I took a few pictures tonight. The lights are not as bright as my cellphone camera makes them out to be but there is plenty of light from the two florescent lights to see everything inside the storage building.

Also, I looked up the amount of sun available in North Alabama and the average sun hours / day here is 4.43. This number means that throughout the year the sun is shining bright for an average of 4.43 hours a day. This is an important number because it tells you how much sunlight you have to work with.

For example, an average of 4.43 hours a day X 45 watts = an average of about 199 Watt hours a day (4.43 X 45 = 199.35). But that's what the solar panels can produce, then you loose some charging the batteries, etc., and that total loss is probably 30%. This means that long term I can count on 139 watt hours a day (199 Watt hours X 70%).

The two lights together consume 10 watts and "in theory" I could run them almost 14 hours a day off solar power (139 watt hours / 10 watt load).




    • Trash to Treasure

      Trash to Treasure
    • Tape Contest

      Tape Contest
    • Gardening Contest

      Gardening Contest

    50 Discussions


    2 years ago

    I bought the same system to light three outbuildings and charge their batteries - as well as trickle-charging my generator battery. Worked great for about 4 years in AZ sun, then stopped charging. I learned that these amorphous-type cells only last about 3 or 4 years.

    Moseley JasperT

    3 years ago

    I have had these for a year now. One set is the only power needed for my driveway gate well the battery to lol. I just used a marine 12v battery there. There is one powering two lights under the carport with 2 6v golf cart batteries from advanced auto, and about to do the same setup for outside Christmas lights on my home. Well worth it. A lot lf freedom with'em just do NOT plug in anything that does not have a three prong plug unless you buy a sign wave

    3 replies
    freebird1963Moseley JasperT

    Reply 2 years ago


    Just getting into solar and wondering why the 3 prong is a no no and why you'd need a sine wave and what you mean by that. Thanks

    Tom HargraveMoseley JasperT

    Reply 3 years ago

    Thanks for the comment. Other uses since I've installed my solar panel:

    I'm using my existing setup to float charge my lawnmower battery over the winter.

    I'm planning to add a small decorative pond and will use solar power to run the pump during the day.


    3 years ago

    I think that we should all try our best to make a difference on our power consumption and installing a solar panel is a wonderful way to do our part!


    3 years ago on Introduction

    Great project !

    Do not try to use more power out of your battery than 20%, that will extent the battery life, and not leave you in the dark if you have some bad weather over a few days, remember for every watt you take out 1.5watt has to go in.



    4 years ago on Introduction

    I use a Harbor Freight 45-watt kit for my shed as well. It works really well. A couple of times I left the lights on. Even with the lights on all night, the battery still kept charged. Two modifications I'm planning on: 1) My kit didn't come with a switch for lights. I have to rig one somehow. 2) My shed gets hot. I do have a screened window but it doesn't help that much. My plan is to get a 12 volt 120MM computer case fan and rig it up as an exhaust fan. You can pick those up fairly cheap.

    1 reply
    Tom HargraveJasonO1

    Reply 4 years ago on Introduction

    A 12VDC PC cooling fan is a great idea! You could even control it with a cheap mechanical home A/C thermostat, the type with contact springs. You could set the thermostat to turn power to the fan on once the inside temperature crosses a predetermined point, something like 95F.

    LOVE this building and I live in Middle TN, so I can make the trip to Fayetteville. I've been thinking of adding a shed behind the house for my craft room, but had the same problem as you (didn't want to run electricity AND live on a wooded lot with limited light). This was great info for me! Thanks for the post.

    One thing I learned already is my old marine battery is too far gone but I thought it might be. The battery won't hold a decent charge overnight even after being charged by a good 15 Amp plug-in charger. I bought a small garden tractor battery and I'll put it in Monday morning.

    I also know from watching the voltmeter on the charge controller that once the sun goes behind the trees the battery charges very little. But I intended this project to provide light when I'm in the shed in
    the evening getting stuff and putting stuff up and I won't have the lights
    on very long.

    You may find that, depending on how much direct sunlight you have and how long you want to run the lights, you need to add solar cells to provide the light you need.


    4 years ago

    cool projects I'm in N Alabama Too

    uncle frogy

    4 years ago on Introduction

    I being a little paranoid about things like leaks and strength I would have attached the panels to a metal or wooden cleat that was attached to the roof on the top of the roofing's ridges. great project

    uncle frogy

    1 reply

    That appears how all the other solar panels are mounted. They have an
    aluminum frame that takes a fastener from the rear. These panels have a
    plastic frame, or at least a plastic cover, that makes mounting from
    the front easy.

    If these panels were going on a house or another
    building with a water tight roof I would mount them the same way. As
    they are mounted the top 2 screws are protected bu the top roof section
    overhang and if I see any signs of leaking past the bottom screws I can
    reach in & seal them with RTV without removing the panels.


    4 years ago on Introduction

    re: "But even with 13 total solar cells I'm only looking at 195 watts total, and that's at peak charge."

    That would depend upon your storage, the 195 watts total is your output of your solar panels. If you had ten batteries you would have more wattage capacity.

    You could use up your storage and the panels might take a couple of days to recharge the batteries to full capacity but if you are not using the charge constantly through the day it should work.

    It would not work for a constant load like a freezer but you could power your lights and some power tools.