For years I have wanted to cut the wires and be done with the power company. With the ever increasing power rates that are only going to get higher I came to the realization that this was the ideal time to make this happen. I don’t have unlimited resources and thus I needed to do it in the most cost effective way possible and yet not throw the lifestyle of myself or my family back in time to the 1890’s. The system I have come up with would make Dr. Frankenstein proud, but once everything is complete and operating it will be a cheap and effective system. I decided to unplug at this time of year as it gives me the summer to get everything in place and all the bugs worked out before next winter. I decided to go with a 12 volt DC battery bank system and generators to top up the battery banks and provide AC power for critical loads such as laundry and water pumping.
In this series I will try to take you along on this roller coaster of a ride into the offgrid lifestyle. Hopefully you will see that although it’s not all Rainbows and Unicorns the final outcome more than makes up for the problems along the way.
Before going offgrid you need to think of what your ultimate goal is. Do you want to save money long term? Make money selling back to the grid? Be independent? These and more questions need to be asked and answered truthfully before you dive into your offgrid project. For me saving money and being independant were and are my main motivating factors.
Once the decision to go offgrid is made a system design needs to be done. There are four main areas that will need to addressed in the design and we will go into them in detail below but they are : Batteries, Generation, Distribution, and Load.
Batteries are the heart of my system. Without them everything else is moot as they provide the power and storage to make the system work. There are two main kind of 12 volt acid batteries on the market one being the Automotive style surface charge battery and the other being the Deep Cycle battery. The type to use in an offgrid project is the deep cycle battery as they can handle the charging and discharging involved with being offgrid much better than the automotive battery.
Where do you get deep cycle batteries? Well you could go out and buy them new. You can buy Off Grid batteries from many sources including many of the big box hardware chain. You can also buy and use Deep cycle marine, Golf cart Batteries, Industrial Batteries, etc. If you plan to buy your batteries new be prepared to put out hundreds and possibly thousands of dollars depending on your storage requirements. I have over 800 amp hour of battery storage which cost me less than $200 dollar. How did I accomplish this? Buy locating dead batteries at the dump and at yard sales and rebuilding them. Even maintenance free batteries can be repair as long as the cells of the battery are ok. I won’t go into the process of rebuilding a battery as I intend to dedicate a whole article and possibly a video to this subject.
Once you decide on your course of action for battery sourcing, you will need to decide on how much storage capacity you will need. When I was figuring this out I discovered it isn’t a cut and dry answer. I decided that I would consider 2 days of storage acceptable. What this means is that I can go at least 2 days with no charge being added to the system before the charge level drops to an unusable level. Calculating this isn’t straight forward and involves a fair amount of estimating and straight out guessing but if you over calculate and end up with more than needed it is better than under calculating and sitting in the dark. The calculations aren’t overly difficult to do and there are sites on the internet that can do a better job than I can at explaining how to do this.
Once you have your battery bank you’ll want some way to charge your batteries up. There are many different ways to accomplish this from Solar to wind to dedicated engine ran chargers. In my system I have decided on 2 primary ways and 1 secondary method of ensuring my batteries remain as full as possible. My first primary method of recharging my battery banks is with regular ac>dc plug in chargers. These chargers range from 6 amp to 40 amp and charge whenever my generator is on. The second method is actually not up and running yet, but will be a dedicated engine ran battery charger built from an old riding lawnmower engine and a 130 amp Delco Alternator. Once it is up and running I will do an article on it so you can easily create one yourself. By using this dedicated battery charger I will be able to keep my banks charged without having to use the generators except for the heavy loads. The secondary system I have in place is a 15 watt solar array that helps keep the batteries topped up on a sunny day.
Getting the power from your batteries to all your loads may seem pretty straight forward, however if you are used to working with ac power there are several big differences you need to consider. With ac power it gathers a a central Breaker or fuse panel and is distributed out to loads from there. Even if the loads are in remote building power still comes from that central point. With dc power you need to keep your loads as close to your batteries as possible or increase the size of your wire the farther you get from the source. The reason for this is that dc power is noted for what is called line loss which means it loses power the further you get from the source. The way I have dealt with this issue is to place a battery bank in each building on the farm. There are two ways to increase the size of dc wiring. The first way is to increase the physical size of the wire bundle as in the gauge of the wire and the second is to increase the number of wires within that bundle. Standard household ac wiring is 14 gauge solid core wire which is perfect for ac as it travels through the core of the wire, but dc travels along the outside of the wire which means that standard 14 gauge housing wire is very inefficient and possibly even unsafe for the distribution of dc power. If you look at the wiring in most rv’s you will notice that it is 14 gauge multi strand wire that is used. For heavier loads such as inverters they will use 10 gauge multi strand. The more strands the better as this give more surface area for the power to flow on which equals less line lossage. Each circuit you create needs a minimum of 1 fuse in the line and should be sized according to the line size and the load on that line. On 14 gauge wire the maximum fuze size should be 20 amp and on 10 gauge maximum should be 35 amp. There are exceptions to this like if a load is within a couple feet of the source you could probably get away with a 30 amp on 14 gauge wire, but why risk it. If you need that many amps either run another line or increase the size of the wire.
Loads are the devices you are running on your system and can range from lighting to HVAC to kitchen appliances. Many people think that 12 volt lighting means they will have dim lights and be squinting to read like in older rvs, but lighting has come a long ways in the last few years and if you visit a company like glenergy.ca you’ll find 12 volt dc bulbs that allow you to repurpose your exsisting ac fixtures In my system I have replaced all the desktop computers with laptops which are powers by laptop car chargers like these I found at Bestbuy.ca . You can install a 12 volt operated propane furnace available from an rv dealer and while there you find many other 12 volt appliances from blenders to water heaters. You can also convert many ac devices to dc by removing the ac motor and replacing it with a dc motor of the same specifications. I will cover converting from ac>dc in another more indepth article sometime in the hopefully near future.
There you have it a basic off grid 12 volt system. I hope I was able to take some of the mystique about off grid life away and hopefully some of you may decide to join the movement. In the next installment I will go into batteries and the rebuilding of them in more detail.