1. Disclaimer: The subject of solar power is a complex one and this article is only meant to
to be a very basic understanding of how solar works and what you can do with solar power.
2. Parts needed for Solar System.
One or more solar panels
A Charge Controller
12 volt storage batteries
A power inverter to change 12 volts to 120 volts.
Solar Panels. A solar panel collects energy from the sun and converts that energy into
a DC electrical current which is then sent to the Charge Controller.
Charge Controller. This is a device that monitors the output from the solar panel and regulates
how much energy is sent to charge the batteries. It will prevent over charging the batteries.
A PWM is a basic controller and does the job, however,
an MPPT controller makes better use of the incoming energy. Worth the extra cost.
This regulated solar energy is then sent directly to charge the battery or batteries.
The battery or batteries. This is where the energy, created by the solar panels, is stored.
The Inverter is the device that changes the 12 volt battery voltage to 120 volts for appliances.
So let's get started with building a solar system beginning with the heart of the system, the batteries.
Grab a coffee, this might be a long one.
The first thing you need to decide is what you need to run in your house during an emergency.
The more items you need to run the more batteries you'll need and more solar to charge them.
Such things as refrigerators, air conditioning, electric stove are huge resource hogs.
The amount of batteries and solar you need for these is beyond the scope of this article.
The first thing to consider is a deep cyle marine battery with as many amp hours (AH) as you
A typical marine deep cycle battery is 105 AH is the example we'll use.
We'll also plan on two of these hooked
in parallel which will give us 12 volts and 210 amp hours.
Google parallel 12 volt batteries
or simply look at the images at the bottom of this page. It's not that hard to do.
So now we know how much power we have to work with. 210AH (amp hours).
Now we need to know how much power we'll actually need.
The first thing you'll need to determine is how much each of the items, you intend to use, draws in power.
You can get the watts for each item from its data plate or use a simple basic watt meter
Just plug the watt meter into the wall and then plug your appliance into it to get its power use in watts.
Make a list of each item and power in watts to calculate total power you'll need later in this article.
Using the watts information you gathered above, you can plug the numbers in as shown below.
Short Breather. As you can see from the chart above, you can easily get more use out of your
simply limiting the high watt appliances. Do you really need a coffee maker and toaster?
A coffee press takes no energy, as one example, and there's always instant coffee.
Remember, what ever power you take out of the batteries, you going to have to replace
by charging them either via generator or solar. Next up, Inverters.
Inverters basically take the 12 volts from your batteries and convert that to 120 volts for
Many come with multiple outlets and USB outlets for charging cell phones and laptops.
Hook up is simple. Many come with clamp ends that attach to the negative and positive terminals on the batteries.
Larger ones come with terminals to wire direct on both ends.
Inverters come in 2 flavors. Pure Sine Wave and Modified Sign Wave.
The technical details are not as important as how they work.
A modified Sign wave inverter will run chargers such as your laptop and cell phone and
lights with no issues. Same for coffee makers, toasters, hot plates etc etc.
Where a modified sign wave converter fails is when dealing with electonic devices
as some microwaves and televisions.
You might get issues with displays on the devices not working normally,
higher power consumption than normal, or some things just might not work at all.
Should your budget allow it, always go with Pure Sign Wave inverters. 12% more efficient.
Size of Inverter: In the example above, the total watts we need is 1,974 watts
but you don't have to go that big. Size the inverter based on what items are most likely to
be used at the same time.
By regulating what items you use, you also help to preserve the batteries longer.
Real world example: During Hurricane Irma I ran my small tv, laptop, cell phone, a 400 watt
and 2 table lamps with 8 watt LED bulbs for several days on a
Potek 750 watt modified sign wave inverter with no problems.
So now you have the battery or batteries and your inverter hooked to them.
Congratulations, you now have 120 volt power in your home powered by just 12 volts.
Now you need a way to keep the batteries charged. You could just do this with a generator and
but that would kind of defeat the purpose of this article.
Solar Panel Types: The types are, Monocrystalline Solar Panels and Polycrystalline Solar Panels.
In general, Polycrystalline Panels are less efficient when hot but the difference is not that
and they may be cheaper.
For this discussion we'll assume you're going with Monocrystalline but the same
calculations apply to both.
For the purpose of calculations, I'll use this solar calculator based on our needs from above
of 1,974 watts.
Remember, cut the number of watts used and the number of solar panels you need goes down
In this case, 1,974 watts of needed power requires
(6) 100 watt solar panels with 50 Amp MPPT controller.
1,974 Watts equals 164 amp hours times 2 for 330 amp hours or (3) 12 volt batteries in parallel.
This 330 amp hours is doubled to keep the batteries from being discharged more than 50%
This is based on 5 hours of direct sunlight per day.
So, just for fun, let's take my power requirements during Hurricane Irma.
I had (2) LED 8 watt bulbs in my table lamps. (Equivalent of 60 watt bulbs) Total based on 3 hours of 48 watts.
I ran my laptop 2 hours per day for 200 watts.
Ran my rice steamer for 18 minutes or 120 watts.
Cell phone charger 2 hours or 12 watts
Small TV 2 hours or 200 watts.
Total watts = 580 watts times 2 to protect the battery is 1,160 watts
Devide by 12 to get amp hours of 96 amp hours. Well below my 210 amp hour batteries.
By way of the calculator, I'll need (2) 100 watt panels and 30 amp controller which I have.
In closing, the sun doesn't always shine but I found I could top off my batteries with
and battery charger in a very short time.
Yes, you can use a battery charger while the solar is still hooked up.
Just make sure to always keep your batteries outside your home.
For reference this is exactly what I'm using. Solar kit and extra solar panel.
I might add that many people live in restricted communities.
If that's the case, you could rig up a system to
make the solar panels easily portable.
Simply put them outside when you really need them.
If the disaster is still going on, the last person you'll see is someone from the HOA coming to complain.
A brief word on an EMP attack, natural or man made.
The solar panels themselves have been tested and shown to not be effected in most cases.
Where the panels were effected is if they were hooked into your system at the time of the EMP.
The electric surge (EMP) simply follows all wiring it can see.
My panels are just stored away in my metal shed in their original boxes.
The weak link in an EMP event is the solar charge controller and inverter.
My advice is have a spare controller and/or inverter, wrapped in alm foil, inside a faraday cage trash can.
Where I don't use solar or inverter normally, I have just one of each inside my faraday cage trash can.
25. One final word. Stay far away from these "so called" solar generator boxes.
They don't even come with solar panels which are extra.
Some range in price up to $2,400 for what could be easily duplicated and more powerful
for less than $500.
Most come with, at best, a 90 amp hour battery which is nothing considering a common
Marine battery is 105 amp hours.
Look at the diagrams below. I bet you can figure that out for less than $2,400.
My favorite review of a portable solar generator box.
"I love it. I can take it anywhere and re-charges quickly with my generator or back in the garage."
Can you say stupid? Kind of defeats the whole purpose of having one.