Off-Grid Container Houses


Introduction: Energy

So here we are – in the chapter dedicated to “Off-Grid” container houses, where you will find what does it take to stay independent from the municipal grid (electricity, fresh and waste water), but at the same time create warm and comfortable ambience for permanent living.

It’s true that off-grid living creates many challenges. Initially, you may see some of them as insurmountable obstacles, but I hope, that after reading these chapter,  you will find answers to many already “verbalised” questions.  Most likely however, you will also find new, unknown, earlier unsuspected areas of concern, prompting you to formulate more questions.

Customised Containers designed for habitable spaces usually come with external ports (hookups) for connections to municipal services (water, sewer and electricity). If your container house is located on your residential property next to your principal (traditional) house, in most cases you will be able to directly hook-it-up to your existing water/sewer and electrical systems. When the container house is located within the limits of the city as a standalone unit, municipal permits and professional help will be needed (please note that connections to municipal grid and installation of relevant counters can be done only by authorised personnel). In both cases, your main effort will be focused on connecting your container home to the existing municipal services.

In an off-grid location you will have to, not only build your container house (what actually may be the easiest task), but also develop all mentioned services (energy, water and sewer) before even thinking to hook-them up to your house. While a lot of these efforts can be done in DIY approach, you will certainly need Local Authority’s permission (for example for Septic and Well). However, in contrast to the city, you will also have to meet more rigorous requirements driven by Environmental Protection Acts. Electricity (if solar), from a legal point of view will be probably the easiest problem to solve (although by no means cheap). Legal issues related to attractive alternative sources of energy like wind and hydro power may be more complex.

Off-Grid-Shipping Container Home

Picture of an off-grid container house – courtesy of Yamamar (San Francisco, CA, USA).

One of the most important advantages of Off-Grid living is the serenity of the surrounding unspoiled Nature. It’s the gift from still graceful Mother Nature, but as recipients of this priceless gift we should do everything possible to minimise our impact on Her. If it is true that winners take all – here both parties must be on the winning side!

The three most important problems related to off-grid living are: availability of Energy, Fresh Water and disposal of Waste. In this chapter we will focus on energy.

Starting point to any plans is thorough estimation of how much energy is needed (on average per day) for the comfortable off-grid living. Obviously, it will depend on:

1. Family size and habits

The biggest obstacles to “switch” our lifestyle to off-grid conditions are our wasteful habits. Off-grid living will put strong limits on many of our deeply rooted rituals. For example, instead of daily bath in a full tub of warm water you will have to settle for a short shower.  Similarly, you will have to start paying attention to often “freely” running tap water (washing dishes, fruits, brushing teeth etc…), avoid “excessive” heating or cooling (in other words keep interior temperatures at reasonable levels, turning lights off when not needed, dimming when suitable, unplugging idling devices (most of us have no idea have wasteful are all these phone and computer chargers when left idling) and so on…

off grid bath

You may have to abandon long sessions in the bath and look for “pleasures” in close contact with nature. Source: This is Money (UK)

When it comes to family, for most adults, moving to off-grid area is a conscious decision, but it may not be so for children used to enjoy all sorts of “water games” in the bath ?.

2. Appliances

Modern, energy-efficient appliances are a must in off-grid environment (look for Energy-Star compliant models and compare their power ratings (expressed in Watts or kW) before buying. Whenever possible, verify if it may be beneficial to buy 2 (or even 3-way appliances), so they can be directly supplied from 12Vdc batteries (eventually 24Vdc or 48Vdc) or even run on LPG gas (fridge and water-heaters).

Note, that such solutions are very popular in RV industry, so there is no reason to dismiss them, although such decisions must be taken on the “case-by-case” basis. RVs are sort of “Temporarily Off-Grid Houses”, usually only for very limited time when out of the campground. Your off-grid container house is rather a long-time solution.

  • a. Solar panels generate DC voltage (usually compatible with standard batteries (so 12Vdc or 24Vdc). Any DC-to- 110Vac converter has limited efficiency (in other words, some electrical energy will be lost during conversion and dissipated in the form of heat). Not much can be done about that when it comes to power-hungry AC appliances like stove, microwave, washing machine, dishwasher, heat pump as well as majority of small kitchen appliances. They almost “by definition” operate on 110Vac (those more power hungry on 220Vac). In contrast, all electronics (TV, Stereo, computers, phones… you name it…) internally run on low DC voltages so when powered from 110Vac, they use one more level of conversion – in this case back from 110Vac-to-12Vdc. Most of phone, laptop, tablet chargers are hot when in use (to make it worse, they also consume energy when idling). It then makes sense to keep 12Vdc interior installation, use 12V run devices (TV, Stereo….) and (whenever possible) larger appliances.
  • b.When it comes to AC/DC/LPG run appliances a good example will be fridge. Most likely between 3-way models you won’t find units with highest electrical-efficiency. However, 110Vac/LPG model still may have an advantage if (for whatever reasons) you will run-out of electrical power (several consecutive rainy or cloudy days, or simply failure the system).

Note you may also find that the high efficiency 110Vac fridge may still be the best solution if you plan to have an “emergency” diesel generator. Far from being eco-friendly, it will keep your fridge alive for quite limited time. However, if you plan to use large supply of LPG gas for space and water heating, 2-way fridge may be a better solution.

Off grid-Fridge-Sunstar-01

Well, recently you can find on the market large, DC compressor-based refrigerators operating at 12 or 24Vdc.

The manufacturer (C4P Inc. uses innovative, an energy-efficient technology that eliminates initial burst of power characteristic for 110Vac-run compressor each time it turns on (usually 3 to 6 times a day).

These so-called “Solar Refrigerators” are especially designed for off-grid locations.

7.4 cu. Voltray Solar Fridge runs on 12Vdc/24Vdc. Source: Creative for Products (C4P) Inc.

  • c) Fortunately, lights, thanks to LED-technology do not consume too much energy. While most of them are designed to operate at 110Vac to substitute traditional incandescent bulbs, by their nature they operate at low DC voltages so are perfect for any off-grid locations.
    Nevertheless, in an off-grid and presumably eco-conscious environment you will have to get used to the fact that there is no room for waste. Bottom line – turn off lights when not needed or reduce their intensity (dimmers) to conserve energy.

As you can see, important part of planning successful relocation to off-grid environment, is an in-deep analysis of suitability (from the point of view of energy) of any appliance. And while for economic reasons you may initially reuse some of already owned equipment and devices, at least you should plan the electrical installation in your container-based house having in mind predictable technological future.

Container House Advantage-Power-01

Off-grid living in Cargo Shipping Containers house. Note the inclination of solar panels optimizing efficiency of PV conversion. Source: Advantage Power (Australia)

3. Estimated Energy Needs

Assuming the family of 4 and assortment of energy-efficient appliances, good thermal insulation and reasonable use of resources, it is estimated that the single-family off-grid house located in a moderate climate zone will need about 8 -to-12 kWh of energy per day.

Just to put it into perspective – according to recent US EIA reports an average US household with family of 4 needs about 30 kWh of energy per day (Tennessee 42kWh, Hawaii 17kWh) This absolute number may be a bit “intimidating”, but things do not look that bad, once we get into details.

First of all, it is important to know where this energy goes. Statistically, household’s energy consumption falls to the following categories (Source: Visualcapitalist):

a) Heating & Cooling 47%
b) Water heating 14%
c) Washer/Dryer 13%
d) Lighting 12%
e) Refrigeration 4 %
f) Cooking 3-4%
g) Electronics 3%
h) Dishwater 2%

This brings us to the following conclusions:

  • a. Heating and Cooling: Almost half of all consumed energy is used for heating and cooling. In absolute numbers, this energy is determined by house’s total square footage (it is expected that eco-friendly, off-grid container houses will be smaller than traditional residential ones), climate zone (for obvious reasons) and age of the house (new houses with good insulation, dual-pane windows and quality doors will use much less energy). It may be important to mention that cooling usually takes more energy than “equivalent” heating because the efficiency of electrical heating is higher.

Note also, that the use of Thermo-Pump for heating is more economical than traditional electrical heating although as long as the temperature of outdoor medium (air, water or soil) is higher than about 5 degC (40 degF). In other words, pumping 1kWh of thermal energy from exterior into home will require less than 1kWh of electrical energy. At lower temperatures the relation will change.

Location in tropical zones may decrease these numbers (depending on the required level of comfort, you may limit the use of AC), however in areas with temperatures falling below freezing point there will be an increased demand for energy (it wouldn’t be a matter of comfort but rather of survival).


Off-grid two-40ft containers house relies on energy generated by roof-mounted solar panels. Source: Living Big in a Tiny House

  • b) Water heating is the second biggest energy consumer, shortly followed by washing and drying.
    Fortunately, existing technologies based on absorption of solar energy can be used for heating of eventually “pre-heating” the water, what will significantly reduce the cost of keeping the water at a desirable temperature by an extra electrical or gas heater. Another energy saving (at least seasonal) can be achieved by outdoor drying (combined factor of sun & wind). As an extra benefit, you will get “natural freshness” of clothing and linen.The quoted above statistics, seem to be a bit outdated (Report represents traditional housing and is based on pre-2015 data). No wonder, that recent technological progress as well as off-grid environment will change some of the above numbers:c) Lighting: Reported lighting consumption is certainly overestimated as it reflects incandescent bulbs characterized by very low efficiency. The introduction of LED-based lighting drastically reduces consumption of energy to about 2-to-3%!
  • d) Electronics. This segment obviously grew from what was reported a few years ago. More complex and powerful electronics (combining useful devices but also a lot of useless gadgets), larger assortment of devices we consider necessary and in general – our “wasteful” habits contributed to noticeable increase of energy consumption by this segment of household appliances. To be objective, when you decide to move out of the city to some remote off-grid location does not mean that you want to cut contacts with the family, friends and the whole world. You can stay in touch exactly thanks to mentioned electronics. The only difference is that now, you will be able to selectively choose whom you may want to contact, and which of numerous world affairs to follow.
  • e) Cooking: It’s important to realize that most likely in an off-grid environment you wouldn’t find in your “neighborhood” coffee bars, fast-food stores, restaurants, grocery shops…. The kitchen will have to take on many tasks that in the past were “outsourced”. This will certainly increase the energy consumption well above the reported above number. While you may really miss some of these “benefits”, the good news is that you will leave behind “fast” and “industrial-type” food!


Designer’s vision of an Off-grid, container house. Source: CCP Prefab Houses Co. Inc, (Foshan, China)


4. Technical Notes:


  • a. 1kWh (kilo-Watt-hour) is the energy consumed by a 1,000 Watts-rated appliance running for 1 hour. To be more practical – for example a 1kW-rated microwave needs 1,000 Watts of continuous power when turned on, however if it is running only for 6 minutes a day (one tenth of hour), it will use only 0.1kWh of energy. The 2kW heater operating for 5 hours a day will need 10 kWh of energy.

Now in short words:

  • b. To calculate the amount of required energy per day, you have to multiply rated powers (in kW) of every of your appliances by the expected time of use per day (in hours).
  • c. The installed power (solar panels, wind or hydro turbine…) must be able to generate more energy per day than calculated demand due to the efficiency of generation, storing process (batteries) and conversion to 110Vac.
  • d. 1kW of installed solar panels will not provide 24 kWh of energy per day, because PV panels generate electrical energy only during the day so the outcome (generated and stored energy) will depend on the length of the daylight (latitude of your location and season), angle of exposure to sunlight (determined by latitude, daytime and season), weather (clouds, rain), dust (in the air and accumulated on the panels) and degradation of panels’ initial efficiency (wear & tear process) – to name only a few most important factors.
  • e. Given the unpredictability of weather (possible rain, clouds etc…), the size of the installed solar power and the capacity of the battery bank should be “over-designed” to accommodate situations when very little energy will be generated during the day.


This “Octopod” structure emphasizes the importance of roof. It will protect containers from exposure to sun and by that – minimize the need for cooling. Source: Off-Grid-Essentials

Note that, the rated installed power can be generated only in most optimum conditions: direct exposure to sun at and angle of 90 degrees, no clouds, no shade, no dust and obviously new panels.

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