Tiny home cabin in the woods

Image by Ben Chun via Flickr

Renewable battery storage for off-grid homes: Tiny House

About TinyHouse Movement

TinyHouse Movement originated in the United States post a series of events including the Katrina hurricane leading to the collapse of housing infrastructure. This led to people building their own homes, especially on wheels. Eventually, more people start to experience and realize the beauty of simple, minimal, and self-sufficient lifestyles.

Alternative Sources of Energy

The advances in renewable energy technologies have reached a stage where they can be afforded at an individual level. Due to this, a new era of self-sufficient (replacing energy from the grid with self-produced energy), sustainable, and decentralized households is emerging. TinyHouse Movement is one of the major outcomes of such an era. People can now build and live in a house of their choosing with minimum environmental impact and be completely self-sufficient. Some of the biggest advantages include energy independence (freedom), smaller environmental footprint, and zero external influence on the amount or price of energy consumption.

One of the goals pursued by individuals embracing TinyHouse living is minimizing environmental footprint. The use of locally available energy sources such as sun, wind, and biomass is one way to reduce environmental footprint. The current way TinyHouses are completely off-grid is by a combination of propane/wood, solar/wind energy, and battery and/or generator. For off-grid applications, generators can be fuelled with diesel fuel, gasoline or propane. Propane/wood fuel can be used for cooking, space heating, and hot water while all the other electrical appliances can be powered using solar/wind energy.

A renewable energy source, such as the sun, is virtually unlimited but not available 24/7. Thus, it is crucial to optimise such energy sources by storing energy with a battery for later use at night or other days (Why do we need energy storage?). Especially for TinyHouses, where the energy system is off-grid, energy storage ensures reliable continuity of crucial appliances at times of no generation i.e. during the night or dark days (winter).

Off-grid Living with TerraBattery

TerraBattery is a solution for TinyHouse residents that desire energy independence and/or are committed to eco-friendly living. By storing excess renewable energy and dispatch when needed with a non-toxic and completely recyclable system, energy demand can be met per our (your) environmental values.

The battery system is safe and non-explosive, lives up to 20 years, and perfectly-suited for daily cycling. The cost of the system is lowered by its long lifetime, and the size of the system is compensated by its outdoor endurance and resistance to all weather. This allows you to make the most out of your solar panels and be well-equipped for cloudy days.

Figure showing a comparative study of TerraBattery against lead-acid battery, lithium battery and propane

Figure 1. Comparative scores for selected features. Terms: Affordability = Operational and capital cost over lifetime; Safety = Explosion due to failure or accident; Sustainability = Environmental friendliness and recyclability; Simplicity = User control and interface; Size footprint = Physical size and weight.

A System for Anyone and Everyone

As energy requirements vary from person to person, TerraBattery systems are built to be modular and scalable.  

Module Normal capacity Boost capacity[1] Continuous power[2]
TBTH-1 1 kWh 2 kWh 0.2 / 0.5 kW
TBTH-2.5 2.5 kWh 5 kWh 0.5 / 1 kW
TBTH-5 5 kWh 10 kWh 1.25 / 2 kW
TBTH-11 11 kWh 22 kWh 2.75 / 5 kW

[1] Up to 7 complete cycles a year.
[2] Peak power is twice as much but only for a few minutes.

Propane vs. Lead-acid vs. Lithium-ion vs. TerraBattery: Cost Comparison

We performed a case study from a cost point of view for each of the technology as compared to TerraBattery.

The most commonly used technologies to go off-grid are batteries or generators. As for generators, people are commonly using propane-powered systems, which are cleaner than diesel. While there are two main types of batteries: lead-acid type and lithium type.

A propane-powered system consists mainly of two components: the generator and fuel tank. The capital expenditure in this case includes the generator, tanks, and related components while the operational expenditure is the propane fuel including its transportation on site.

A comparable battery-powered system consists mainly of solar panels/wind turbines coupled with a battery. The capital expenditure in this case is the generation systems (solar/wind), battery, and related electronics. The operational expenditure is rather minimal with no transportation or refueling requirement.

Energy system Expected lifetime Real price per kWh (EUR/kWh)

End price over lifetime (EUR/kWh/cycle)

Propane 10 years 950 0.26
Lead-acid (AGM) 3 years (1000 cycles) 589 0.59
Lithium-ion (LFP) 14 years (5000 cycles) 681 0.14
Lithium-ion  (NMC) 5 years (2000 cycles) 910 0.46
TerraBattery 21 years (7500 cycles) 789 0.11

The following are assumptions for the price comparison:

  • Propane system includes generator cost
  • Cost of batteries only
  • Battery system cost is for nominal usable capacity of each technology

An example case for end-user:

  • 11.4 kWh (5kW) TerraBattery + 4kWp solar panel
  • Total system price for off-grid setup: €17,999
  • Final end price of energy for the user: €0.21/kWh

The levelized cost of lithium-ion, TerraBattery, and propane-powered systems are quite close. While as seen in figure one, TerraBattery is the most sustainable option as you can use renewable energy on-site w/o need for fuel transportation all the while having a battery that is 100% recyclable and safe.

If you’d like to know more about TerraBattery,  you can download our brochure here.

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