My Simple Solar System

I have done it. I have stepped into the world of solar power. Not in a big way mind you – just a baby step.

I just picked up a Harbor Freight 45 watt solar panel kit. After doing some research I decided to start out with this kit. It is not the cheapest dollar per watt kit out there – but was not bad at all. I paid $136.00 for the whole kit – and now I will add an inverter, batteries, and auxiliary equipment.

45 Watt solar power kit

I am no expert when it comes to solar stuff. I know you need the panels, a voltage regulator/controller, an inverter, and batteries. To summarize – the panels convert energy from the sun into electrical energy and the controller regulates the current charging the battery.

The battery? Stores the energy that the sun provided. The inverter converts the energy stored in the battery from DC to AC current to power…..whatever.

off grid battery and inverter

Well – my solar panels are on the roof, wires run, charge controller running and inverter installed. Just one problem – the system will not fill the role I originally intended. I am usually pretty good at math – but in this particular situation I failed to recognize the results of a simple math equation right in front of me.

three 45-watt solar panels on rooftop

First off – my plan was to use the solar panels to charge couple of marine batteries which would then power a very small refrigerator. The fridge is needed for my sons insulin in the event that the grid fails. Here is the problem:

Solar panels produce 45 watts of power for every hour of good sunlight (approx 8)

Refrigerator consumes 140 watts of power per hour 24/7.

Power needed = 3,360 watts daily

Maximum power supplied from solar panels = 360 watts daily

Obviously I am way shy of getting the power that is needed. I just did not so the math at the beginning. In order to make this successful – I need a total of 10 of these systems. That is not going to work.

To accomplish what I have set out to do – I will have to rethink this project. I need more power – so a larger system is needed. I also need to source a lower power consumption refrigerator.

Another option is to seek alternate types of refrigerators to start with which consume little to no power.

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14 thoughts on “My Simple Solar System”

  1. That’s not a bad kit at all Rourke. You got it for a good price too. We put one of those on my BILs garage last summer. It works well to keep one or two batteries topped off with an occasional heavy draw. We mounted
    it permanently on the roof. That was a good purchase!

  2. Rourke,
    I made the exact same purchase at Harbor Freight. Couldn’t believe the price, so I had to get two.
    Like you, not exactly sure how to apply the solar panels to every day life, so I’m very interested in your progress and what applications you come up with
    My thoughts / suggestions are the following:
    1 Power for an outbuilding on my property.
    2 Power for my well pump for emergency situations but it runs 220 volts, so that would require multiple batteries and a 220 inverter.
    3 Emergency bug-out power
    Look forward to your future posts on this topic.

  3. Rourke,
    I’ve done something like this, a small step into the solar world with a DIY solar cart. Currently I’m running a 15w panel, but I’d like a 40w or (2) 40w panels. I’ve built 2 Deep Cycle batteries on constant charge/maintenance while the sun is shining.

    If you can manage, two 6v gold cart batteries (wired in parallel) will make a DAMN fine energy bank without shelling out cash for the “designated” solar batteries.

  4. The Harbor frieght 45 watt panels are an excellent buy especially when they are on sale. I installed this on my motor home two years ago and it works great. Every evening I get 2-4 hours of laptop time from the system. I could probably get twice as much time but I’m real careful to not draw down on the batteries too much. The first thing I did was making a solid frame to hold the panels. My frame secures all three panels together and even has a handle on it (since I needed to put it on the roof I had to have something to hold onto). The second thing I learned was don’t skimp on the wiring. With 12 volts you need heavier guage wire and shorter runs. And last; don’t forget to fuse your load. Batteries have the ability to put out 400 amps or more. If you short circuit your system you can start a fire before you can disconnect the battery.

  5. I highly recommend “Solar Power Your Home for Dummies”, it has provided some excellent guidance on solar power, as well as making your home more energy efficient.

    I haven’t gotten the wife to approve my solar project yet, but hope to now that I’ve got a new job and a little more income. I’m going to take an old camping trailer, fix it up, and make it solar powered.

    A few tips from what I’ve read in my research…

    You should consider getting a charge controller if you don’t already have one (it looks like the kit included one), to make sure you don’t overcharge the battery. Also, make sure the battery and inverter are well ventilated, as the battery will emit small amounts of hazardous gas, and the inverter will produce a large amount of heat.

    As far as batteries go, from my reading it sounds like a Marine or Golf Cart battery is ideal, and for optimal battery life should never be discharged beyond 50% of capacity. So it may be a good idea to get a battery charge monitor, and possibly a second battery.

  6. rourke,
    hey did the same thing myself! picked up a 1000 watt invertor and two 160 amp hour batteries at bj’s club i did get two of the panel systems going to tie them together and see how they work. please keep us updated on your system

  7. I am planning on picking up the same system from harbor freight myself. I think it is a very good deal for the money. I am planning on getting a inverter and three batteries to finish of the system. It is just the right size for my apartment and my land lord is willing to let me put it up on the roof of the building so no one can mess with it.

  8. You got a really good price on your system. I too am coming at solar from an RV perspective as mentioned in another comment. I currently have purchased three of the HFT kits, but have not yet installed them. I have the batteries from my RV that I will use initially until I can get more.

    A resource you might want to check out is He is VERY opinionated, but also very practical and knowledgeable. Another great blog on different alternative energy is then make a donation and go to the member section. His articles on UPS’s as invertors is really useful. The invertor in a UPS is a True Sine Wave invertor but they are available cheaper than many MSW invertors.

    Hope you and your readers find this useful.

  9. You did get a good deal; it’s now $180 on sale. I am just getting in to solar myself and the hard part for me is figuring out how many batteries I need to power things. For example want to power 2 fans and the Frig over night. Anyone got any ideas on the best way to figure those types of things?

    • HunterTX –

      I am not not the best at these things – but with solar you basically have to figure out the output capabilities of the panels, the capacity of the batteries, capability of the inverter – and the daily requirements of the devices you are wanting to power. If the solar panels produce less power than your daily consumption – then your batteries will eventually run empty. This is fine for short term situations.

      To get more specifics – just Google “How to determine solar power needs” and go from there.


  10. Well done for starting the first steps with solar power. Our fossil fuel supply is running low and we need to look at alternatives. Green energy is the way to go, it just takes time to catch on.

    Camping trips are now changing to include solar panels to charge our accessories, such as mobile phones, ipods and computers… we can’t do without them anymore. Solar panels are also being used to produce our evening light. Solar panels give us the flexibility to camp where we like and still have the power we require.

  11. Harbor freight panels are ok But you need a good air gap between them & the roof.. keeps them cooler .bigger panels need up to 4″ gap.


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