home power system

Home Power System – published on July 31, 2021

Outfit your offgrid basecamp

We are going to look at a remote bugout location that has a cabin, shed, or pole barn with no electrical service. In order to have comfort and safety, we need to generate and store electricity onsite.

Not just your bugout location basecamp

This article is also for anyone who wants to make their home more resilient to interruptions in utilities. We all have a steady stream of food, water, and energy coming into our home. Without a functioning electrical grid, everything breaks down. There are shortages of food, water, and fuel. Without fuel, there will be shortages of everything. This article is an introduction to putting together an independent home power system that you can install in any structure. We will lay out the equipment required to install a stand-alone backup electrical system that is not connected to the electrical grid or the internet. Basic tools and wiring connection skills are all that will be required.

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The baseline

Many people have invested in whole house generators that have enough capacity to run everything in their home. They can run on diesel, propane, or natural gas. Their advantages include the ability to use your existing outlets, lights, and appliances. Their disadvantages include high fuel consumption and their static installation on a concrete pad next to your home. Here is an example:

Generac 70432 Home Standby Generator Guardian 22kW/19.5kW Air Cooled with Wi-Fi and Transfer Switch

This generator will put out 20,000 watts (22k surge, 19.5 continuous). This is a lot of power – enough for most homes to run everything including high load 240 volt major appliances like clothes dryers and ovens. But it takes 2.5 gallons of propane per hour at half load. This is 4.6 pounds of propane. The typical 20 pound propane tank you use for your barbeque will run it for just over four hours. So your options to fuel this monster are having a 500 gallon residential propane tank installed next to it or using it with natural gas that is piped into your home.

The total cost of purchasing this generator and having an electrician install it is about $9,000. More if you go with the (better) option of an onsite propane tank.

Another thing to consider if you live in an area that has wildfires, hurricanes, or floods is that an independent home power supply put together from portable components is portable. Be sure and see our article on The Ideal Wildfire Shelter. If you have to evacuate, you can take it with you. We are going to show you how to spend under a third of this nine grand to power your life when the grid goes down.

Power generation

Without the grid, we must generate electricity onsite. Historically, most homes had a 200 amp service from the power grid. At the input 240 volts, this is 48,000watts (48 Kw). Newer homes can have significantly less electrical service, but nothing like the limitations we have when we generate electricity onsite. See the section below on efficiently using your stored power.

The first priority is solar. This is a great foundation for an independent home power system. It’s all about upfront cost and then passively reaping the rewards for years. But the sun is an intermittent fuel source. It’s only available during the day and cloud cover can severely impact how much energy your panels receive. Because of this, having adequate (or abundant) power storage is required. The electricity that the panels generate cannot be used to directly charge the battery bank. A solar charge controller is required. It takes the 24 volt DC power from the panels and steps it down to 13.8 volts for the batteries. Solar charge controllers also feature an integrated smart charger that will maintain the batteries without overcharging them. Both the solar panels and the charge controller have either economy or premium components. The most efficient solar panels are made from monocrystalline silicon and the most efficient charge controllers are Maximum Power Point Tracker (MPPT). Here is a monocrystalline solar panel kit from Amazon that includes a MPPT controller: Renogy 200 Watt 12 Volt Monocrystalline Solar Panel Kit w/ 40A Rover MPPT Charge Controller

Generator – we need the ability to charge the battery at any time. Even though we will lower our electrical requirements with 12 volt appliances, fuel efficiency is the most important factor. We want to run everything off of the battery bank and use solar as our base supply with the generator making up the rest of the power generation.

Because of this, we do not need a large generator, but it would be nice if it could run a major appliance when needed. To do this, we need at least 2,000 watts of power. Inverter generators adjust their engine speed to the electrical load. This allows them to be much more fuel efficient than traditional generators as well as extending their engine life. They also produce extremely clean pure sign wave power. Amazon has this lightweight and quiet 2,000 watt inverter generator that will charge your batteries or run most major appliances with 16 amps of 120 volt AC power: Champion Power Equipment 100692 2000-Watt Portable Inverter Generator

Charging your deep cycle batteries can be accomplished directly from the generator if it has a 2 amp, 12 volt port. But all this does is throw a couple of amps at the batteries and it can overcharge them unless you disconnect it manually. Smart chargers have several cycles that progressively charge batteries to properly top them off – and then it will maintain them at almost full capacity. If you are installing this in a home with grid power, a smart charger will also keep the batteries at full charge (without overcharging them), as long as the grid is up. It’s important to get a battery charger that is designed for the type of batteries you will be using. This one from Amazon covers all the different kinds of sealed deep cycle batteries: NOCO GENIUS10, 10-Amp Fully-Automatic Smart Charger

Power storage

Our onsite electrical generation sources both have issues that having the ability to store power will drastically improve. The solar panels power will trickle in – especially on cloudy days. The generator will burn precious fuel and have a unique noise that can draw attention – especially at night. Since neither power source is optimal for night time illumination, communication, and entertainment we need to generate power during the daytime and store it for use after dark.

There are two primary choices for power storage – lead acid batteries like Adsorbent Glass Matt (AGM) or GEL batteries or Lithium Iron Phosphate (LiFeP04 or just lithium). All of these are sealed batteries that can be wired in parallel to increase the storage capacity while maintaining the same voltage. This will allow us to scale our electrical storage by using a bank of two or more batteries. To do this, wire the batteries positive to positive and negative to negative. Be sure to connect the positive cable from the charge controller on the positive terminal at one end of the line of batteries and the negative cable on the negative terminal of the battery at the other end. This will allow all of the batteries to be charged equally. This video shows how to wire four batteries together in parallel:

Note that lead acid batteries like AGM and GEL should only be taken down to 50% before being recharged. This is to prevent damage to the battery. This is a big hit to the usable storage capacity. Lithium batteries can be taken down to 20%. They also have a longer life with more charge/discharge cycles. To get more storage capacity without having to wire multiple batteries together, you can use a larger battery. Here is a 200 amp-hour deep cycle lithium battery at Amazon that will work well with the solar system and battery chargers above: 12V 200Ah Lithium Iron LiFePO4 Deep Cycle Battery.

We can significantly improve your family’s comfort and safety for about $1,900 (so far). This includes the solar panels with controller, the battery charger, the 200 amp hour battery, and the backup generator:

Efficiently using this stored power

An amp-hour (Ah) is a unit of measure that is one amp of power drawn for one hour. The battery above is rated at 200 amp-hour. That is the total capacity. The useable capacity is 160 amp-hour (200 – 20% = 160). This means it will put out 160 amps in one hour. But we would never want to draw it down that fast. One complete charge/discharge cycle per day is a good benchmark to shoot for. If you have minimal sunlight, you will probably be using the generator every day. You should take the opportunity of the generator run time to charge your devices like phones, computers, and toothbrushes.

All your devices should have a placard on them that shows the power usage. Sometimes it is given in amps and volts and other times it is in watts. Amps x volts = watts. If you have a 12 volt device that is rated at 3 amps, it draws 36 watts (3 x 12 = 36).

A 12 volt light bulb that draws 1 amp will use 1 amp-hour per hour. If you have six of these bulbs on for five hours a day, they will use 30 amp-hours (1 amp-hour per bulb x 6 bulbs x 5 hours = 30 amp-hours).

We have 160 amp hours of usable power and 200 watts of solar panels with an extremely efficient generator as a backup. With this, we can power quite a bit of our life:

1. Illuminate the night with 12 volt lighting.
2. Recharge cell phones, tablets, and laptop computers for a typical family.
3. Run smaller appliances like a coffee grinder, a small television, or a can opener.
4. Keep a 12 volt portable refrigerator/freezer cold.
5. Run a fan or a 12 volt evaporative cooler (but not an air conditioner).

This gives your family light at night, communication, entertainment, cold food and ice, and the ability to maintain core body temperature in hot (but not humid) environments. Evaporative coolers are not very effective in high humidity.

The limitations of our independent home power station

Notably absent on the list above are heaters and air conditioners. Heating and cooling takes the most energy of anything in a modern home. It is possible to scale up your solar and battery capacity to run these devices, but it can get expensive very quickly and is not portable. Anything with an element that heats up like a space heater, a stove, or a crock pot will quickly drain all but the largest (and most expensive) bank of batteries. Air conditioning and heating are beyond what we can do with this system, but we can make your home or bugout location safer and more comfortable.

Connecting everything up

These are two ways to charge your battery:

1. Solar charge connector – always connected to the battery with the ring terminals.
2. Smart charger – clipped onto the battery terminals as needed.

The smart charger can either plugged into a normal 120 volt AC outlet to maintain the battery when the grid is up or the generator 120 volt AC outlet to recharge the battery as needed.

Connecting devices to your battery

To charge our devices, we need to connect QC3.0, USB, and 12 volt DC. We will use a multi-outlet with one QC3.0 port, two standard USB 2.0 ports, one 20 watt USB-C port and three 12 volt cigarette sockets: Quick Charge 3.0 and USB C Charger 20W 3 Socket Car Cigarette Lighter. To connect it to the battery terminals, a 12-Volt Adapter Plug Socket with Eyelet Battery Terminals is used.

Battery voltage equals capacity

Note that this multi-outlet also has a voltage meter. With no load, this will show a full charge of at least 12.7 volts, but the smart charger may take it a little higher. This is because most 12 volt systems will provide a little more voltage to compensate for line voltage drop in the cable run to the device being powered. Lithium batteries can safely be taken down to 20% capacity. The voltage meter will read 11.75 volts at 30% capacity and calling this the minimum voltage will give us a margin of safety. The absolute lowest voltage is 11.5 volts. Go below this, and you will damage the battery. The working range is 11.7 to 12.7 volts. If we put 11.7 at 0% and 12.7 at 100%, then each tenth of a volt is 10% of the battery life. If you check the voltage and it shows 12.5, your battery is at 80%.

Powering 120 volt AC devices with your battery

These can be devices that you use daily like coffee grinders, can openers, and even a microwave. Note that microwaves will draw more than their rating. They use additional power for their electronics, lights, and fans. A typical 700 watt microwave will draw about 1,000 watts. To run these devices, we need to convert the 12 volt DC power to 120 volt AC (standard household current) with a converter like this one: Renogy 1000W 12VDC to 120VAC Pure Sine Wave Inverter with Eco Mode

The USB and 12 volt socket box with the battery terminal socket will add about $30 and the 1,000 watt pure sign wave converter will add about $230 for a running total of $2,160:

The lithium battery terminals are 8 millimeter (5/16”) machine screws that screw down into threaded sockets. The pure sign wave converter, the 12 volt socket, and the solar charge controller all have ring terminals that will fit these bolts. Stack all three positive and all three negative ring terminals together and securely tighten the machine screws. The smart charger will clip onto these machine screws when needed.

Illumination

We are going to use a combination of wired 12 volt work lights and rechargeable work lights. This 12 volt lights will plug into the sockets on the multi-outlet box and the rechargeable lights will be used for bedrooms, bathrooms, and garages:

WF 36W LED Work Light Magnetic Base Mount Portable LED Flood Light

LED Work Light, 2 Pack OTYTY 2 COB 30W 1500LM Rechargeable Work Light, Portable Waterproof LED Flood Lights

Refrigeration – 12 volt cooler fridge/freezers

Chest style refrigerators are much more efficient – especially when the door is opened all of the time. They do suffer from fewer options for organization, but we need to prioritize efficiency. Note that these are not portable coolers. They have a compressor and a thermostat and will maintain a set temperature This one from Amazon features both a larger refrigeration bay and a smaller freezer bay: COSTWAY Refrigerator, 55-Quart Portable Compressor Freezer, -4°F to 50°F, Dual-Zone Electric Cooler

The total cost

Two each of the wired work lights and the rechargeable work lights are going to add about $140. The refrigerator/freezer will add about $350 for a total investment of about $2,650 at the time this article was published. This gives you two ways to generate power onsite, battery storage, lighting, and refrigeration. All of these components work separately from the grid, the internet, and your phone – although the solar controller has an optional Bluetooth module you can get.

Your home power system

Purchasing separate components has advantages and disadvantages. Compared to a whole house generator, these components require setup time and we need to purchase separate 12 volt lights. But we have a home power supply that is portable in case we need to evacuate and it consists of easily replaceable components. Whole house generators are a single point of failure that just gulps down gallons of fuel every day. They are nice to have for intermittent power outages, but they have disadvantages in situations like snowstorms and hurricanes where you have no grid power for days and still don’t know when it will come back on.

Whether it’s your home, an offgrid bugout location, or your in-laws backyard you are camping in after evacuating, setting up an inexpensive home power system will light up your life, keep you comfortable, and keep your tribe alive. Stay safe!

Next article: Prepare For a Power Outage

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