Andrew Jennings is a wonderfully sharing fellow and long-time reader.  He’s been designing and installing solar projects for more than 12 years.  So when he offered to do a details looking at home solar for both the prepper and economically minded, it didn’t take but a second to accept.  Here’s what he sent in:

Note: George has done an outstanding job laying out the benefits and some of the specifics of using solar energy over the years. The goal of understanding and planning a system can seem daunting. With a little research and familiarity with tools, anyone can do it. In an attempt to simplify and bring some perspective to the Solar options for most people, I offer the following notes for those interested in the topic.

Lesson 101: Energy, Solar Electric Systems, Economics


This is it, the thing we all need and live on. I don’t just mean the electricity available in a home’s outlet that runs all the Necessities of Life, I also mean the energy that we use as we move through our day. Just try a couple nights without sleep and then try to move a mountain, it just isn’t going to happen. It seems much of the world is in an energy struggle, whether it’s the gas at the pump or the amount of education and drive needed to succeed to the top of the heap. If you’ve never experienced an energy disruption or power outage, it can be more than unsettling.

I’ll shed light on using solar to collect energy from out most abundant energy source, the sun.

Solar: Power

Bet no one ever told you that there is enough light striking a small area of the Southern California desert to power the entire country?

When Bell labs made the first useful solar panel in the 50’s, commonly referred to as a “Sun Battery” or “Sun Generator” the technology was quickly put to work and has now become a world-wide powerhouse of economics and usefulness.

Solar Power Uses for the Public: 3 types:

Grid-Tied Solar Systems:

The world “Solar” as is used in our marketplace and on the news, is about producing power mainly in the goal of saving money from Electricity bills, or going ‘green.’ The basic premise is that instead of buy power from a utility company, a person instead produces power for their own use. These types of systems, the most common, make electricity available to the home, synchronizing power with the Utility, and any excess power beyond the home’s use flows back to the utility for the next closest home. This reduces the amount of power a utility has to provide to their customers. During the evening, when the sun is down, the residence uses power from the utility. The measurement between the amount of power a solar system puts into the utility grid compared to the amount it pulls back out, is what’s termed “Net Energy Metering.” Basically, think of the utility as an Energy Storage Account. During the day you make deposits, during the evening take credits. The little round meter on your electric service records the difference and the company bills or offers you a credit depending on that difference. These types of systems will not function when there is no Utility power, by law.


Off-Grid Solar Systems:

This is where the slogan “Off the Grid” comes from. These systems were the first use of Solar panels. This type of system is what powers satellites in space, remote cell phone towers, weather stations, and anywhere there is no option for Utility power (or for those who want to ‘unplug’). Most off-grider’s start with a generator as their power source, but after burning costly fuel just to power a light or appliance, the maintenance of the generator, and the annoying and inconvenient sound of them, people quickly look for the better, although more expensive alternative of Solar, with batteries.

Whereas these systems can be used with or without solar as the primary power source, they’re all the same in that there has to be some sort of energy storage – Batteries. These systems vary greatly in their components and capabilities and comprise less than 1% of the solar market. There are many additional parts and equipment needed for these systems and very quickly even the best electricians run with their tails between their legs when they face one of these; solely because they don’t understand how they work. After a bit of digesting the basics, they’re actually quite simple.

Perhaps the biggest difference between Off-Grid systems and On-grid ones, are the type of inverter they use. Any local automotive store sells an inverter that can be connected to the cigarette lighter of your car or it’s battery to produce our US standard 110V Alternating Current. However, there are much fancier and robust versions of these Inverters in the solar market. Specifically, the inverters for the solar market also have battery chargers built in so that they can both produce useful power from the batteries, and also charge them from an AC power source like a generator, or DC power like that produced by Solar panels. As batteries produce electricity from Chemical Reactions of metals and are sensitive and expensive by nature, steps must be taken to not over fill charged by solar panels, another piece of equipment is necessary – a charge controller. Off Grid systems for homes function best when they lots of battery storage as our culture is used to running lots of various and large appliances. For fun, learn to read your electric meter on your Utility-connected home, and you will learn how much power you use even when you think, “I’ve only got a couple lights on.” Depending on your desired goal for off-grid systems, the cost of batteries can add up quickly. There are many who’ve ‘unplugged’ but the cost of the battery bank alone cost $40k. There are others who can do with very little energy usage, and only spent $1k. When it comes to Energy storage and power requirements, ‘load calculation worksheets’ are a must as without them, most find they are sitting in the dark, wondering what happened. Many systems have the ability to start a generator automatically when the battery power gets low, and for these clients, there is little to no difference between living on the grid or off it.


Hybrid Solar Systems: Utility Powered and Off-the-Grid, The Best of All Worlds

Hybrid systems are ones that interface with the Utility company for Net-Metering/bill savings, but also seamlessly and instantaneously provide power to the home when the Utility power shuts off. These back-up systems sit idle most of the time, with the power from the solar panels going to the home or going into the Grid for credits, but the moment the utility is absent, they provide power solely for the home from energy stored in the batteries, and from what the solar panels can provide. These systems can use a generator as a source of power when the batteries are depleted or when the solar panels are not able to provide adequate power. And like off-grid systems, the Inverter/ Charger will use power from a generator to recharge batteries if desired.



When’s the best time to go solar?

As a solar professional, I’ve talked to countless people about the industry, the equipment, the financial paybacks, and solar’s future over the years. Generally, people know little about solar other than a scientific news blip about “Nano” this or “Efficiency” that. Remember that recent rover, comet lander and satellite mission from the news? How do they get their power to operate, what does NASA trust for power? The Sun.

Where I live in California, I’ve paid as much as 44 cents for a unit of electricity provided by our For-Profit utility company. Elsewhere in the US, some people are still paying as little as 8 cents for the exact same Kilowatt of power. Have you ever wondered if our country is immune from the prices of energy going up or the purchase power of our currency going down? Perhaps you should become a Peoplenomics subscriber if you need some clarity.

I’m not into predicting the future but history has shown it’s hand, the truth is that the cost of electric energy will go up, and there are not any new hot alternatives coming to the forefront anytime soon. Remember all those new US solar companies coming online a couple years ago… well, they’re in pieces laying on the ground. Right now, according to some of my contacts, it costs less to purchase a solar panel right now than it costs to manufacture them. Combine that recognition with the reality that any purchase that includes at least 1 new solar collector (module, panel) stands to receive a 30% Federal Tax Credit (TARP funds at work) off the entire system and installation – and it’s what I call a ‘no-brainer.’ Note, this credit expires after 2016 and I’m not a tax professional. There are people out there putting new roofs on their homes, because that was part of the solar cost – because the equipment is guaranteed for 25 years, and their roof wouldn’t last that long, so it’s included in the tax credit. When I show my prospective clients the highly detailed and precise financial analysis and payback numbers I’ve calculated for them given their precise circumstances, those with moderate 10 year paybacks (when the system has paid for itself), with Return on Investment numbers well over 10%, often decline going solar – I find it funny that I usually see a new car in their driveway the next time I pass by their neighborhood. I’ve seen solar pay off as fast as 5 years for some, with ROI and IRR number at nearly 20%, it all depends on your specific circumstances, and any reputable company will charge you nothing for you to find out.

So when was the best time to go solar?

Yesterday. When the power is out or the bills are too high, Last year.

But while the lights are on, and people listen to the news that our world circumstances are improving and the challenges are fading away, I’m fine adding another couple solar panels to my roof, and saving for a larger battery bank.

Even if a set of solar panels and an inverter aren’t in your future, remember the Sun can do so many fun things for us. Perhaps get a Solar rechargeable flashlight that sets in your window and read with it at night, buy a solar sun oven and make a meal in your office’s parking lot… learn how to use the sun, for some sort of energy or another, you’ll like it.

In general, the residential solar provider are now owned by banks, with lots of schemes like their a ‘zero down lease.’ And while that makes a lot of sense from the fast-talking mouths of salesmen, don’t forget why a bank would offer such an option, because it makes them money, when instead, that security could be in your pocket.

Very General and Helpful Electric Stuff

Volts X Amps = Watts, or V=W/A, or A=V/W

Amp Hours (Ah) = The amount of energy storage at a given voltage


6Volt Battery with 100Ah has 600Watts of Power, energy storage


1500Watt Hairdryer plugged into the 110V socket in my bathroom uses 13.6 Amp 1500W / 110V = 13.6A

Voltage is Additive in Series,
Amperage is Additive in Parallel


DC wires, breakers, and disconnects should be rated 156% of their predicted/measured values

AC wires, breaker, and disconnect should be rated 125% of their predicted/measured values.

Most solar equipment will have it’s input, output, or capacities on a sticker somewhere on the product

Only expect to get 70% of the power out of any one part of your system to account for efficiency losses and de-ratings of equipment.

Helpful Google design searches:

-Voltage Drop Calculator (try to be less than 3%)

-Ampacity charts

-Wire size calculator

Simple Sample Math Problems:

Question: what size wire do I need from my batteries to my inverter, given they’re very close together, just a couple feet away. What size breaker/fuse should I have protecting that bit of wire?

2400 Watt Inverter running off a 48Volt Battery Bank
2400W / 48V = 50 Amps of current

Multiply 52 Amps x 1.56 (as noted above) = 78 Amps.

The appliance I want to run uses 550 Watts from my 110 AC outlet. How long will my 400Ah battery bank power that, knowing I should only use 50% of the battery power to help preserve their life.

550W / 110V = 5A

Answer, you should be looking for a breaker/fuse that disconnects at around 80Amps, and wires that are rated for 80A. Now go ask google for a wire size calculator, and head down to the hardware store once it tells you the answer

The appliance I want to run uses 550 Watts from my 110 AC outlet. How long will my 400Ah battery bank power that, knowing I should only use 50% of the battery power to help preserve their life.


In the field electric observations worth noting

– 12, 24, or 48 Volt Systems

Higher voltage means cheaper wire and increased power handling

Higher voltage make more efficient use of various components, like Charge Controllers

Higher voltage requires more batteries to create the 48 Volts

Lower voltage systems are more common and used in RV’s and similar.

12 appliances and electric parts are common and readily available


Lead Acid batteries need maintenance, water levels maintained, occasional de-sulfating

by running higher-voltage equalization charges.

Lead Acid batteries can be dangerous due to battery acid and explosive venting gas

Gel and Sealed batteries are expensive and have a shorter life span than Lead Acid

All batteries have specific charging parameters that differ between the various types

Solar Charge Controllers

PWM (pulse width modulated) chargers need matching and often rare solar panels to be connected to them. PWM chargers often need large wires installed from the panels due to low voltage input MPPT (Maximum Power Point Tracking) charge controller are very expensive, but efficient.

MPPT charge controller often need to be programmed

MPPT charge controllers handle higher voltage inputs for reduced wire size and more options for panel selection

– Panels (a single solar collector is properly named a ‘Module’)

Most have 25 year output guarantees

Most are made in China, Taiwan, or off-shore

Are 1/4 the price they were 7 years ago

Often come in the 30+ Voltage range

Haven’t changed much in many years, they only get bigger in physical size

– Generators

1800 RPM versions work most efficiently for battery charging but cost a lot

Propane version run clean and can have a massive fuel tank located close by

Auto start features, and push button starting are extremely helpful

Have short life expectancies as they’re only meant for occasional use, not ‘prime power’

– Mounting

It’s best to mount equipment like solar panels with industry known and engineered


Times were once brighter for solar installers like Andrew…there was not a lot of knowledge online and knowing what to get – and where to get and at what price really meantr something.  But today, online retails are undercutting the serious installers who used to make some of the money on equipment mark-up.

He also passed along this, which is important:

If things like rolling black outs, EMP’s, Depressions, Coastal events…. take place, I’d suggest a $400ish dollar investment in a ‘solar generator’ could save lives, and provide comfort. There are options already available in the 400-1800 range, but anyone handy could make one themselves.

I don’t make as big a deal about the solar power system I designed and installed here are Uretopia, because I don’t like to brag (!).  But unlike 99.5% of “prepping” websites, we really do live out in the “toolies” and we really have a pretty good solar system – and yes, it is fair to say that UrbanSurvival really is solar-powered.


Ure’s custom-designed solar system comprised of T-post verticals, 5/8” rebar for the rails, electrical conduit for the top “hinges” and 3/4” schedule 40 PVC pipe for summer high sun angles.

The whole system (when new) set me back about $22,000 in parts alone, including stacked grid-interactive inverters and big 60 Amp MMPT controllers. There is about $2,500 in batteries, involved. 

Today, you could clone my system for likely have that price due to the falling price of panels.  And it is one of the best investments (other than marrying Elaine) that I’ve done.

My sincere thanks to Andrew Jennings for contributing to a “gown-up” discussion of the one thing everyone can so at some level to reduce dependence of foreign oil.

On that note, have a great weekend…enjoy Peoplenomics tomorrow, and see you Monday.

Write when you get rich,