Solar Power for the Home with Acceptable Levels of Power (Part One and Part Two), by BePrepared

Part One

I am a Gen X Nerd. I can talk Apollo Mission minutia as detailed as any S.A.D. Hams can about their custom antenna. And one thing that struck me as a small child is that while Voyager I and II had used “miniaturized nuclear reactors” (which are still working to this day) NASA used a large solar array to power the World’s First Orbiting Laboratory, Skylab. If you go to the Space and Rocket Center in Huntsville AL, you can see a 1:1 scale representation of the solar array used for the missions, it’s not small. I recall once at Space Camp (told you I was a Nerd) asking an engineer once about the efficiency of the solar cells on Skylab. “Oh about 20%” he replied. “Why so low?” I asked. “Well the technology is new and we hope to get to 50% by 1990.”

Fast forward to the last two decades. The Chinese have FLOODED the solar panel market (this is another Rabbit Hole) with cheap(ish) small solar panels. The dreams of many Survivalists, (with a Capital S… they were doing it since the Fall of Saigon) is off-grid, non-moving parts power. Solar was promised to us in the late 70s/early 80s as a way to “stick it to the man” and “get off the government tit”. (Sound familiar?) Yet the cost was INSANE for solar, a unit to provide what a 2k gas gen set would do cost $9k (in 1983 dollars, some $30k today) you can see why I have been skeptical.

And don’t get me started on wind power, Kalifornia has had that wind farm in the pass for DECADES… I don’t see it as a shining example of “economical” Wind Farms. “But if it’s too cloudy for solar, it’s going to storm and a windmill will pick up the load.” No, just no. I can have DAYS of cloudy weather before significant wind to make power with a small windmill… and that is in hurricane country. No… I even live on a “mountain” and no I don’t use Wind power. (Unless I can successfully kidnap a Politician running for re-election, then a windmill MIGHT work.)

Can solar be something a prepper can use? Certainly, I have on recent trainings with Mr. Dolio and at the G-Camp. In fact the G-camp went so well I never had to charge radios, tablets or phones in the classroom the entire week.

What I have learned is that solar has over promised, and we wanted to believe.

When I say “solar power” to you (I will assume you know nothing about it, as all good articles do) you might think it is this miracle of God/science (pick your side) to provide us power with no downsides. Well yes and no. Humanity has it’s ways of using solar energy to warm ourselves and feel better, cause we have a long history of using the Sun’s rays to help us. It’s only recently someone thought of making electricity, and even more recently someone thought to use the Sun to make it.

I won’t bore you with the science. Basically the Sun’s rays strike a surface and the electrons interact to make a voltage. This voltage is in excess of the surface’s ability to hold electricity so it passes the electrons off. Combine ALOT of the surfaces… you get a measurable amount of electricity. Now multiply that by THOUSANDS (go take a good look at a solar panel) and you get a small (but steady under constant sunlight) voltage, than you can then use.

This is solar power. Not a huge voltage that will be available all the time and not enough to run your home by itself. You need other solar “boxes” to run a full system. The power from your panels needs to be moderated, my panels can run from 20w to 196w in a matter of minutes because of clouds. So you need a solar controller. This is the link between your panels and your “working load”. Now you can cheap out and buy the cheapest thing around but I’ll warn you, Chinese cheap gets HOT. (Ask me how I know.) You can get a $30 solar controller or you can be an adult and buy what luxury RV builders use for solar controllers. (Hint: they cost more than $100). Now you COULD run something on just solar panels (there are custom freezers cough about the size of a cooler cough) that will run on just a 100w panel, but again. Clouds are a thing.

Best bet is to add a battery to this set up. It allows you to have a power bank to pull from for your power demands. No not your average car battery (although you can use them) you want something that can do some very deep draws down (to 11.5vDC or less, many many times) and not be damaged. Something at least 100ah (Amp Hours) to start. I have run limited appliances with some 100 watt panels, a good MPPT solar controller and a Yellow Top Optima battery (55aH).

It’s not a solid science, it’s a science we can afford. I’m currently running two experiments, household power and partisan power. Both are l o w power by your normal standards but successful so far.

Part Two

In my last post, Solar Power and You, I described the (VERY) basics of how solar worked. About how it seems to have over promised but under delivered (IMO).

I had long wanted to develop some “alternative” power for some aspects of my house, I had no illusion of running my house on some DIY setup I designed (running the AC in summer in the Deep South? Laughable.) but what if I had different solar powered “mains” that could power some essential systems? Like say… a full size freezer? And if that worked how about a freezer and a fridge? How much would it take to run the fridge, freezer and some DC powered rope lights in some rooms? Year round with winter’s short days? And what would it take to have this reliable 24/7 without breaking the bank on components? And could I wire it?
I come from a different electrical background, I worked in Marines Corps Aviation Avionics on KC-130s for eight years and was an Instructor on the subject. We used AC and DC power throughout the air frame and I have a healthy respect for those energies. Do NOT use any of this as a basis for your own electrical “experiments” or DIY without having a proper education in Electrical energies. You Have Been Warned.

In this article I want to go a bit deeper into some DIY experiments I did with COTS (Commercial Off The Shelf) components and the uses I found for them. Like how cheap can I go with reliable power. And so like anyone wanting to save a buck, I started with Amazon and Harbor Freight, specifically a Chinese Solar Controller ($30 on Amazon) and three 100 watts Thunderbolt solar panels (from HF). I also added a panel “connector” to save me the trouble of wiring the three panels together (also HF). To this I added various cables and wires to connect from the connector to the solar controller (you HAVE the Box Of Various Cables, right?) and I had voltage.
I disconnected this (to avoid shocks) and wired in a (long disused) Optima Yellow Top to the set up, reconnected the wiring and I was charging the battery. (YES!) I let this sit for a few hours and decided to stress test the ‘dead’ battery. To my surprise it showed residual voltage and amperage (despite not being charged for some three years). I reconnected the setup the next day and left it for 24 hours.
It took several days to get the battery back to “fighting voltage” so to speak. During this time I became worried of the heat building up the the cheap solar controller. (I was afraid it would melt/catch fire) so I went looking for a good replacement. I settled on a Vectron Connect MPPT controller because they were highly recommended for DIY RV setups. I could not be happier, in fact I bought a smaller model for another project (that I’ll write about later.)
Now I had a working setup, so I mounted it all on a board in a corner in my garage and added some 30A circuit breakers between the controller and the battery. I also added some 15A circuit breakers from the panels to the controller. I then added a 750 watt modified sine-wave AC inverter, with 30A circuit breakers between it and the battery.

NERD ALERT

Now a note about inverters, they take 12v Direct Current (think a flat line) and turn it into a wavy up and down line that is 115v Alternating Current (alternating because it goes up and down). There is modified sine-wave and pure sine-wave and the difference is cost and longevity of the equipment being powered. A sine-wave is the sweep of power from negative 115v to positive 115v that looks like a wave in the ocean. A generator rotating makes the sine-wave naturally. The modified sine-wave, or step inverter does not make a smooth wave of power, it steps the power up and down.
For example (in AC) it can start at 0v, step up to 15v, then 30v then, 45v etc till it hits a peak of +115vAC. It then starts to step down, to 100v, to 85v etc etc till it passes 0v and starts to step down to -115vAC. Positive 115 to negative 115 to positive 115. But in steps.
This works great for some items, not so great for others. You see AC motors that like the constant wave of AC don’t like to be “stepped” it makes them work harder and get hotter, even incrementally. This shortens the life of your motor.
Pure sine-wave inverters step the voltage so incrementally that AC motors can not tell the difference, so the motors last longer and run cooler. The difference is cost, pure sine-wave inverters are sometimes 2x the cost of modified wave inverters.

Back to the Experiment

Now I had a 750w modified wave inverter connected to my battery (via CBs) and what to power as an experiment? Well this was the summer… why not cool the dogs? So for 4 months this system powered a 20” box fan to cool my dogs in the garage. I monitored it a good bit to watch charge rates and battery draw down. I would turn on the inverter in the morning and run the fan all day off solar. Occasionally I ran the fan FAR into the evening to see how far the 55aH battery would last. In my unofficial testing, I could run a 20” box fan from 6am till 10pm at night, as long as the summer suns did their thing. Success in Phase One. A $1000 investment would pay for itself in 200 days cooling dogs in the summer sun.
But what about when I up the power demands? And winter months when the Sun is lower in the sky?

Phase Two

So, can 300 watts of Solar power keep a smaller upright freezer cold? Yes. Kind of.

First you need to have a larger battery, the 55aH of the Optima was not going to get it. So I opted for a 200aH AGM battery. (AGM is the same battery technology as the Optima’s) I wanted AGM batteries as opposed to LiPO4 due to the temperature limitations of LiPO4. (I cover this more in the next article.) I also added a Jupiter 1k pure-sine wave inverter (from HF) for the new load. This added more cost, but I could make more savings soon.
With the lowering Sun, I have limited time to make power however for about 12 hrs a da