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Starting a Remote Home Project
Most people start building their remote home with an AC generator to operate power tools. The generator may be one they plan to use later to back up the solar and wind generators, or it may be one of the cheap throw away types that takes up space in the garage later.
Either generator wastes money and, more importantly, the owner bypasses an opportunity to learn about their future energy system in easy stages.
Electricity is a mystery to most people ...it comes out of a wall socket, or a socket on a generator. Living with your own energy system requires a deeper understanding. The time to gain that knowledge is before and during home construction, and some incremental steps getting there will provide that understanding, and ...save a lot of money.
Money will be saved on the generator, the batteries, the solar panels, the inverter, and the surrounding shelter and infrastructure.
The Case for Diesel
A diesel engine costs more than a gasoline or propane, (lpg), engine. That initial cost is offset by a number of advantages.
True, diesel fuel costs more than gasoline or lpg. But it also delivers more power per gallon due to engine efficiency. A gas/lpg engine consumes fuel that is not proportional to the power it produces, especially at low power levels, or very high power levels. With a diesel, fuel consumption is very proportional to the power production. In the end, engine power production translates to kilowatt hours of electricity.
Diesel fuel is safe to transport and store and will keep for years.
Besides all these good arguments, there's one more. Someone in your area, maybe it will be you, will start a bio-diesel cooperative and the cost per gallon/kilo may only be one fifth of the pump price.
Choosing a Diesel
A single cylinder diesel is generally not a good idea for a generator, especially an AC generator where a constant RPM is expected over a wide range of loads.
A DC generator doesn't require a constant RPM, so a smaller, lighter engine can be used, even a single cylinder engine. But a single cylinder engine vibrates more, and is harder to muffle. The added vibration means shorter engine life, so the savings up front will result in higher costs later.
Ample Power Company has sold thousands of single cylinder Kubota engines that have been marinized for small boat application. The addition of the heat exchanger and resultant raw water injection into the exhaust makes sound proofing possible. That same engine with its factory mounted radiator is not so easily muffled.
Sound proofing an engine requires an enclosure. The heat generated by the engine and DC/AC alternator has to be removed from the enclosure. An engine mounted radiator with a pusher fan can be used to remove the heat, but it will also blow a lot of noise from the enclosure.
To minimize noise and extract heat from the sound enclosure a remote radiator can be used, typically with an electric fan. The engine must have a water pump to circulate the coolant through the system.
Some single cylinder engines, such as the Kubota engine don't have an internal water pump. To use a remote radiator with this engine requires adding a DC coolant pump, as well as the fan for the radiator. Such added complexity reduces reliability of the system and drives up the cost.
A smaller engine can be run more hours to produce the same energy as a larger engine, at relatively the same total fuel consumption. The larger engine will last for a longer calendar time based on engine hours of operation.
A larger engine needs enough battery capacity in the system to absorb higher charge rates, and the cost of those batteries and their maintenance will subtract from the wear and tear savings gained from fewer engine hours.
Confused by all the interwoven parameters and conditions?
All that said, choose a multi-cylinder engine with an internal coolant pump. Select from a supplier with a proven engine manufacturing history. For us, that's Kubota.
AC or DC Generator
There are many considerations regarding AC versus DC generators. Some are covered in an atticle about AC Generation.
However, unless you plan on running the AC generator 24/7, you will need batteries and a way to maintain their charge. A DC generator does this directly, whereas an AC generator requires an electronic battery charger to convert AC back to DC.
To run AC appliances and tools from batteries requires an inverter. Why not just start with a DC generator and inverter?
And what capacity should they be?
The Learning System
Starting with a DC generator, batteries and an inverter provides an opportunity to live with a power system during construction and become familiar with managing the system.
Don't invest in a lot of batteries. Buy a minimal number of inexpensive batteries. Golf cart batteries are usually cheap and will be effective long enough to learn how to manage batteries. If, (when), you end up killing them, as is often the case when one is starting out, you can be thankful it wasn't a large set of expensive batteries.
Invest in a small sinewave inverter, big enough to run the power tools you plan to use during construction. A big inverter will be necessary later, but there will always be a future need for the smaller inverter as well.
Start with a fully automatic DC generator that will be used during and after construction. Trying to properly manage a battery bank by manually starting and stopping the generator is possible, but only if you have good instrumentation and are willing to work three shifts and on weekends and holidays.
Don't purchase a DC generator that is too small. We suggest a minimum of 4000 Watts continuous, with a maximum 12,000 Watts. It's easy to be optimistic about the amount of energy that will arrive via the solar panels, and easy to make a low estimate of energy consumption.
Get used to the generator's automation features.
The Ample Power EnerMatic Controller can be programmed to autostart when battery current exceeds a given amount. For instance it could be programmed to start the engine every time you pulled the trigger on a power tool.
Or program it to start the engine when capacity consumed from the battery reaches a specific quantity.
Both of these start conditions can be combined, (along with quite a few more), and will likely be used later. For instance the engine could be automatically started when the big inverter kicks in to run the electric clothes dryer.
Maybe you want to program it so that it always runs at a specific time to heat shower water at the end of a long construction day.
As the system is operated during construction, you'll learn more about the ways it can be programmed, and the cost of operating it. You'll gain insight on how much battery capacity and solar/wind power will be effective. That insight may save a lot of money!
Solar power is easy to add to a system later. Increasing battery capacity is not easy because it is very bad practice to mix batteries with a different number of discharge cycles.
The Sound Enclosure
Building a sound enclosure with plywood and some other relatively inexpensive materials is quite simple.
Details of that construction are the subject of another article, but it's mentioned here because during construction is the time to build the sound enclosure and measure its success.
While a sound enclosure can be very effective, knowing how effective it is helps makes the right decision about its final location that much easier.
The batteries and inverter should be mounted in or close to the house. To minimize wire gauge, the generator should be close to the batteries. The quieter the generator, the closer it can be.
Start with a fully automatic DC generator big enough to be used during construction and after.
Buy a small sine wave inverter big enough to run power tools.
Buy a minimal battery bank consisting of 6V golf cart batteries.
Learn how to operate and manage the system.
Build a sound enclosure and decide where to mount the generator once construction is completed.