So you have made the decision to power your tiny home with the sun? Congratulations! Solar power is now the cheapest most abundant energy source in the world. It is cleaner than traditional power sources, and does not contribute to environmental degradation.
There are, however, several important considerations, to ensure your solar power system suits your needs, and provides you with the best performance for the longest period of time. Thorough decision making and prudent investment at the beginning of your tiny home solar project will save you time and money later on.
Quick guide to components
PANELS – these harvest the power of the sun, in the form of watts. They come in different sizes which equate to their capacity for harvest ie. small panels can catch a small amount. Panels can be connected and added to easily.
BATTERIES – these store the power in the form of ampere hours – usually 12, 24 or 48 volt options. The size of the batteries determines how much power you can store and access. Ampere hours or kilowatt hours is the measurement of the storage capacity of a battery. These guys are the most expensive part of your system, and also will contribute the most weight.
INVERTER – this takes the stored battery power from low voltage (DC) to 230 volts (AC) allowing you to use the same appliances as you would in a regular grid connected house. The process of changing the voltage does have an associated efficiency loss, and the inverter itself requires power to run. The size of the inverter (ie 3kW) determines the types of appliances you use, based on the power draw (in watts) these appliances require. For example, a small inverter may not provide the power needed to run a blender, which requires a large power draw, and a water pump, and charge your computer all simultaneously. The larger the inverter, the more appliances it will support, however, the more power the inverter itself will require to run and the larger the battery bank required to store the power.
Tiny homes can be run on only 12V (or 24V) DC, negating the need for an inverter and maximising the amount of energy available from the batteries, however you need special 12V appliances, as the plug size is different and won't fit in a 'normal' 230V AC outlet. While it will be cheaper in the short term to choose a 12V system, the appliances you require are more expensive, and 12V systems are extremely difficult and expensive to upgrade.
Considerations for solar power
Weight of panels
Traditionally, residential solar panels are mounted on the roof, maximising solar exposure and utilising unused space. This mounting method is simple and cost effective, however it may not be the most suitable for the tiny house dweller. Mounting on the roof will add weight, and also impact where you park your tiny home. Solar panels should be placed in an area of high solar exposure, with consideration to the aspect (ie. north east), maximising the hours of sun exposure each day. Parked in full sun may not be what you consider the ideal placement for your tiny house.
Another popular option is the solar trailer. A trailer is perfectly suited to many tiny home projects as it allows for the solar panels to be placed at a distance from the tiny house, in an area of maximum sun exposure. Additionally, the weight of the panels does not impact on the weight of the tiny home. An added advantage is the accessibility of trailer mounted solar panels. Should your panels require maintenance they are easily accessible and you are not required to clamber about on the roof.
Solar panel arrays can also be ground mounted, but this option is not as portable as roof or trailer mounted, as you will be required to prepare the ground and build a sturdy (roof-like) structure to support the weight of your panels. As such, this array will be harder to move around, should you wish to try a different placement, or it's time to move your tiny home to another location.
Whether you choose ground or trailer mounting for your solar panels, you will have greater control over sun exposure, meaning you can park your tiny house in a cool and shady spot in the summer while your panels bake out in the sun, harvesting the good stuff for your consumption.
Weight of batteries
You will choose batteries for your tiny home based on the capacity of your solar panels to harvest power, and the amount of power you need access to, based on your household energy consumption. The greater your power consumption, the more stored power you need and therefore the larger batteries required. It is important to factor in the weight of the batteries and the need for secure storage, safe from rodents and the weather.
Household energy consumption
If you are going tiny after having lived in a standard size, grid connected home, you may need to consider your power consumption, your habits, and your lifestyle. For most people living with residential solar, kettles and toaster are relics of a past life. Any appliance which generates high heat generally requires a high input of power, and is therefore not really suitable to solar or, indeed, your new tiny house. The same can be said for air conditioning.
Living with solar requires you to change the way you think about and consume power. What is a need and what is a luxury? Most of us will nominate a fridge, good lighting, phones and computers as required tools for our existence. Thankfully, a well-chosen power system will facilitate the use of these, and other appliances, ensuring we can live comfortably and not feel we are missing out.
Mobile phones and tablets actually only require a very small power input to charge, so you may consider running a small amount of 12V cable to a dedicated 12V charging point – just like the one you have in your car. This is a good way to maximise the efficiency of your power consumption.
Look for appliances (fridge, washing machine) with a high energy star rating, switch to a laptop, and think about what you can run with gas – ie kettle, stove top, oven, grill, hot water system. Think about lighting and make clever choices – LED lights are much more power efficient than standard globes.
The greatest fear for many looking to change to solar is enduring endless days of rain and power restrictions. It is important to understand that we do live with unpredictable weather patterns in Australia, and also that the sun spends less time in the sky during winter and has a lower trajectory. Thankfully, your tiny home gives you the edge over permanent stand-alone solar dwellings. An affordable and simple way to ensure back up power for your tiny house is to go hybrid by installing an option to plug in to mains power, much like a regular motorhome or caravan. This allows you to sit out long periods of inclement weather, by moving to a caravan park or camp site, or accessing the grid through friends or family. Alternatively, you may consider a small generator and battery charger for back-up. A generator is also useful for those times of increased power requirements, such as for running a vacuum cleaner or electric tools.