…On solar

…On solar

I had originally written this as a comment to one of the past solar articles, but as is my habit, I got carried away and it became its own Guest Post, an attempt to expand on the knowledge imparted by previous basic posts on solar power….

“There is much to know about solar, but it isn’t as complicated as most might think, at least for the smaller setups like mine”. (Quote from a previous post)


Well yeah…sorry, but it is that complicated.


I have worked many years as an electro/mechanical designer in everything from medical to aerospace and have never run across a discipline that contains so many UNKNOWN variables that must be estimated for worst case scenarios. And it holds true no matter the size (small systems merely reduce the financialf loss of your investment caused by poor planning and research)

It is VERY easy to get a solar system up and running.

Doing so effectively, efficiently, and cheaply without destroying your batteries by overcharging, over depleting, or having electrical and fire problems from mismatching of system components…not so much.


There are many choices to be made in setting up any type of solar system. These should be addressed before you start to “Plug and Play”.


1) What is your projected load to be? (Averaged over a month’s TOTAL electrical use) Once you have determined this you may want to “switch off” certain components to reduce your load usage.

2) What level of sun power (hours per day of sunlight, winter/summer) can you expect from your site? (geographical location, trees and buildings shade blocking panels and seriously reducing output)

3) Are you going to use a MPPT charge controller (more expensive, but will negate other loss percentages) so as to get maximum performance from your panels? Will you use a temperature sensor to monitor your batteries and optimize charging?

4) What input voltage will you run to your batteries. 12V, 24V, 48V? Will your controller accept the output voltage of your panels and match to your battery bank? Does your charge controller provide for equalization (ensuring long battery life?)

5) What size (2V,6V, 12V, 24V) and type (AGM, Gel, Flooded lead acid) of batteries will you use? Smaller voltages are more efficient but require more. How many? Will they properly charge in the sun time available to your area? Will they have enough amp hours to provide for your 24 hour load (and a NO SUN buffer period) without depleting below 50% and shortening your battery life?

5) What wattage inverter will you require matched to your projected load (usage) does it provide for overload protection to protect itself and the system? Have you bought larger than you need and are just wasting money, or too small and your overload will be constantly be popping? How many AC outputs will you need?

6) Cut-offs, breakers, fuses ( Have you provided the proper safety cut-offs to allow you to maintain and service the system without blowing out components, electrocuting yourself or burning down your house.) a very important consideration.

7) Wiring and connectors. You need to use the proper gauge wiring and connectors for the Volt/ Amps you will be running and match to your components. AC wiring is easy…DC not so much, much larger wiring is required to deal with larger DC voltages and long wire runs are problematic.


All of the above components can affect the percentage of LOSS of efficiency on your system (1% here 4% there, it adds up) so as to reduce it by as much as 50% if you have not done your homework. You also risk fire and or the destruction of some VERY expensive to replace components.


Rather than all of the photos shown in solar articles, I would have rather see the spec sheets on all of the featured components. I don’t care what it looks like, how will it perform and integrate with other components?


My real world suggestion for anyone getting into Solar Power:


1) Buy a Harbor Freight 45 Watt system for about $150 and get familiar with the concept and components.

2) Buy “Photovoltaic’s for dummies” from Amazon.com and study it, run your numbers (many times)and  be honest with your data, don’t fudge.

3) Once you have your numbers, begin shopping components for your system. (Asian markets still have very good deals on quality components)

4) Once you understand Solar, the handyman can save quite a bit making his own panels from purchased “Cells”, making his own cables, panel mounts and sighting and assembling the system.


This is the third time that I have commented here on MSO about Solar and I know that it appears that I am critical, but I have been there and it is easy to waste your money and endanger yourself going into this lightly or blindly. I mean no offense to anyone who puts any info out to the prepper community. Thanks to all who contribute, no matter the subject or level of expertise.


I am in the process of assembling a back-up system of 350 watts from really cool 15”x16’ flexible panels that will go into an EMP vault after successful testing. I expect my main 1300 watt system will take a significant hit during an EMP event.

I also use my 45W Harbor Freight unit to run a drill or saw where I have no power. I have a small battery pack of four small deep cycle batteries in an orange ammo type box and 750W inverter that I use with this. This was my learning system and I used it to work the retreat before I had power hook-up.

Regards, D.


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7 thoughts on “…On solar”

  1. Has anyone purchased the Harbor Freight solar panel? Just curious if it is worth the $150 price tag and what you are using it for.

  2. great article!! been wondering about the Harbor freight system myself, Mike, and been trying to get feedback ( other than their website) It sounds like D is ok with it- I notice it is on sale through the end of March. . . opnions, folks?

  3. D nailed it with all the complexities.
    I just had an 11.8 KW system professionally installed and I can assure you that the average person’s head will spin trying to balance all of the variables.
    I was considering the “do it yourself” approach and started pricing out the components. I would say that’s the easy part.
    Once I realized the balancing act in order to optimize the system and not burn the house down, I sought professional help.
    At the very least, you should have a qualified electrician assist in the planning phase.
    Nice article D

  4. OK, let me expand on the Harbor Freight unit a bit more than in the article. I’m pretty sure that I reccomended it for a solar entry level, yes it is worth the money!

    That said, don’t expect too much from this unit. EVERYONE seems to think a couple panels will do all sorts of things. They wont. 45 Watts is not much (think of the wattage of the light bulb in the room you are now in). You can run a drill, skill saw, a floor fan, a laptop, and charge some batteries. But not all at once. One thing at a time! You will also need a small (preferably portable) battery pack with suffecient amp/hours and a fair sized inverter with this unit. Please re-read the recommendations. I have seen set-ups that slave several Habor Freight kits together to power very small off grid cabins, but you still need to know your load numbers to do this right. Regards, D.

  5. An additional note: Go to Freesunpower.com (thanks to TED from previous post comments) for a ton of diagrams, tools, and work sheets, etc. regarding solar. These will explain in detail all of the above components and issues. Some info may be dated as they refer to MPP as new. It is now pretty common and increases efficiency by about 40%. Regards, D.


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