Best 12volt Appliances & Accessories

What Size Solar Panel Kit Do I Need To Live Off-Grid?

  • Date: July 3, 2021
  • Time to read: 10 min.

Solar Panel Kits For Tiny houses, Mobile RV living, and Sustainable Homesteading

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As the sustainable living lifestyle becomes ever-popular, the growing number of eco-aware people are creating small foot-print environments to suit their everyday living needs and generating a sustainable power source in order to manage everyday tasks and lifestyle choices. Let’s look together at what is needed to prepare a tiny home, RV, or homestead, and the products you may need to purchase. Included will be some figures and running costs plus some results after testing to see what size solar panel kit you might need and if that lifestyle is sustainable.

  • How much power will I be using daily?
  • How many solar panels will you need to power your home?
  • Which type of charge controller will you need to manage the charge to your batteries?
  • How many batteries will you need to sustain everyday life and manage daily tasks?
  • What sort of appliances will I be able to run?
  • Are there different types of cables and fittings required for off-grid systems?
  • What type of accessories can you add to the system to make life easier?
  • Are there any backup solutions available in case you don’t generate enough solar?
  • What are the costs involved in setting up an off-grid power system?

All the questions above need to be answered in order to create an off-grid system to suit your mobile rv living needs. Let’s begin with noting down your estimated usage. For example, you may need to use LED lighting 10 hours a day, so to calculate your Watt-hours Per Day, you need to multiply your device wattage by hours estimated daily to give you your consumption. Watt-hours (Wh) per Day.

Example: A 50-watt laptop running six hours a day is: 50 watts x 6 hours = 300 Wh/Day. A 1200 watt hairdryer running two hours a day = 1200 watts x 2 hours = 2400 Wh/Day. The wattage of an appliance can usually be found on a label or tag attached to the device by the manufacturer. Once you have calculated all the devices you need and the time you need to run them daily, combined together will give you your daily power requirement and determine the size of system you need to buy.

If your device usage is calculated by Amps or Volts then there is a simple formula to convert to watts. Volts x Amps = Watts. We have to make an average calculation on devices that pulsate power such as fridges and freezers. These appliances do not run constantly so we have to estimate their daily consumption. For example, if your 30-liter 12 Volt freezer uses on average 60 Watts per hour, then you need to estimate that it will only run the compressor when you open the fridge to use or re-stock, let’s say 6 hours a day therefore you would use 3 hours x 60 Watts = 180Wh/Day. So to conclude this section let us estimate that your daily power requirement from lights and appliances is 800Wh/Day then you are going to need to harvest that amount of power from your solar panels.

12 volt Solar Panels:
The useable solar panel range is from 100w panels to 500w panels, and combinations of all sizes in between. Now we have your power usage, we need to allow for cloudy/rainy days when power generation will be less than others. To this end, we need to add more solar collection power than we need. The general formula is an additional third. So if 800Wh/Day is needed then you install 1200 Watts of solar panels.

12-volt Charge Controllers:
Charge controllers come in many configurations and you need to match your controller to your panels for the most efficient collection of power. The two main types of controller are PWM and MPPT and the latter of the controller types is the most efficient and reliable. Determining which type of controller you need, a Pulse Width Modulation (PWM) or Maximum Power Point Tracking (MPPT) will depend on your budget and consumption requirement.

12 volt Deep Cycle Leisure Batteries:
Now you need to store all the power you need, and the decision on which deep cycle batteries can be just as difficult as selecting the rest of the system. Leisure batteries consume a large part of your solar system budget and you need to choose the right deep cycle battery bank for your needs. The three types of deep cycle leisure batteries that you should consider are Lead Acid, AGM (Absorbed Glass Mat), or Lithium. All three have plus and minus points to them so let’s begin. Based on our consumption calculation of 800WH/Day and your assumption that your day is 8 hours, you will need to times the hours you need to use the power and divide the number of total watts required by the volts to determine the number of batteries needed: 800Wh/Day x 8 Hour day = 6400 ÷ 12 Volts = 533 AHrs of battery storage.

Lead Acid: On the plus side, they are the cheapest of the three battery types to purchase, but on the minus side are the most in-efficient.
AGM: You can store and use inside your living area without a sealed compartment as a plus. A minus point would be that they are still very heavy and not as efficient as Lithium.
Lithium: Plus point would be that you can use the full capacity of your battery and the power is stored more efficiently. On the minus side, you will pay up to three, maybe four times more for Lithium batteries.

Power Inverters:
Both 12 volt and 120/240-volt appliances can be run on 12 battery volt systems with the aid of a power converter. These devices attach directly fused to the 12-volt battery bank and invert the power output to 120/240 volts. There is however an additional power drain when using the inverter as it is not an efficient way to use appliances. The power that an inverter will generate from the 12Volt system will be determined by the power of the 240V appliance that is connected. It is widely acknowledged that appliances running off an inverter will be considerably less efficient than their 12-volt equivalent. In short, it is best to keep inverter appliance usage to a minimum.

Here are some devices which you can use to help monitor your power usage:

List Of 12 volt Appliances You May Consider:

12-volt Compressor Fridges:
Here we are discussing 12Volt compressor fridges, and this is the biggest concern for van dwellers and tiny homeowners. Fridges are one of the biggest power drawing appliances in most 12 volt systems so it is really important that we understand your solar system. The power consumption of the fridge will also depend on the ambient temperature of your van or tiny home, the warmer the inside of your home is, the more power your fridge will use.

12-volt Freezers:
Freezer performance in the past has been known to suffer due to the power draw and leisure battery storage capacity, but in recent times we have seen a vast improvement in compressor technology and battery capability. Freezer units are so much more electrically efficient, and the latest solar charge system and leisure batteries will almost certainly be able to maintain the continued use of your appliance while off-grid.

12-volt LED Lighting:
LED lighting has now become the first choice of van builders as they out-perform old technology halogen lighting in almost every way, delivering better light output at the fraction of the power thanks to its extremely low current draw. LED lighting is now much more efficient (up to 80%), meaning less heat from the light and a longer life span of the light. Led’s can have a usage window of up to 15,000 hours which means they are rapidly becoming the first choice in 12-volt systems. In conclusion, with the decreased demand of power from your leisure battery and the ever-reducing cost of LED’s means that they should be your first choice of lighting for your Diy van build or Tiny home construction.

12-volt Fans:
12-volt fans have become very efficient and quiet due to the latest brushless DC motor technology. They can be installed in roof vents, sidewalls, and cupboards to increase the flow of air when needed. You can even have portable clip-on oscillating fans of all sizes to distribute the air flow.

12-volt Kettles:
Definitely one of the essential appliances needed in any motorhome or tiny house is the kettle, as where would off-grid life be without a cup of tea or coffee? There’s nothing better than a hot brew after exploring, driving, or working all day.

12-volt LED TV:
LED TVs are now widely available and are quite happy to work off 12-volts. Small portable LED TV’s can consume as little as 1.5 Amps from your solar panel kit, so if you run your TV for three hours you will only use 4.5 Amps, (1.5Amps x 3 Hours =4.5Amps). Larger size 12-volt TV’s use more Amps so please check your user manual for specifications.

12-volt Electric Blankets:
This is a good way to keep warm efficiently because 12-volt systems are limited in power storage and delivery. The more modern 12-volt electric blankets are safer and less power-hungry due to the development of built-in timers and over-heat protection, A typical current draw from an electric blanket is around 4 Amps, so only using your blanket for three hours will only use 12Ahours, (3hrs x 4A = 12Ah). Built-in variable heat settings and adjustable timers will also allow you to leave the blanket on longer.

12-volt Microwave Ovens:
Here we have the most power-hungry appliance you might use. Microwave ovens can run directly from a 12-volt system or via your 120/240v power inverter. If we have a current draw of 120Amps @ 12-volts, and you ran your 750w microwave appliance for three minutes, you would take 6Ah out of your leisure battery system, which equates to (3 mins/60 x 120A = 6Ah). Some important points to note are that the microwave that runs through the inverter will use considerably more power than a 12-volt dedicated option.

12-volt Ovens:
There are many types and sizes of 12-volt Portable Travel Ovens, some connect via your vehicle’s cigarette lighter socket, some connect using Anderson connection, but the preferred way is to connect your 12-volt oven is direct to a dedicated fused circuit of your battery system. These 12-volt ovens are useful for cooking meals or to keep your food hot. The portable ovens are great for outdoor cooking and picnics, just plug into a cigarette socket, and away you go. Great for RV’s, cars, trucks, motorhomes, campervans, and marine use.

12-volt CPAP Machines:
Newer models of 12-volt CPAP machines will work directly from your solar power kit. As with most 12-volt devices, they should connect to your vehicle’s leisure battery system via a dedicated fused 12-volt adaptor that plugs into your cigarette lighter socket. Some models will work via your inverter but you will have poor power efficiency connecting this way.

12-volt Water Pumps:
The alternative to hand or foot water pumps are the 12-volt external and submersible water pumps. These are usually operated by an inline pressure switch so as to only engage the pump when water is required. On average a pump will run for a short time and only draw 4-6 Amps and will deliver 5-10 liters-per-minute.

Transfer Pumps For Petrol, Diesel & Water:
Important device especially in an emergency for refilling your fuel or water tanks when empty. Most modern transfer pumps are super fast, efficient, and transportable which is perfect for moving from vehicle to homestead.

12-volt Cables, Terminals, Fuses & Connectors:
Connectors and cables are just as important as the accessories themselves, Incorrect cable and connector selection could result in a power short or even fire. 12-volt cable is measured by the cross-sectional copper conductor diameter, (in mm²) which relates to the electrical current carrying capacity. The thickness of the cable shroud differs from each manufacturer. 12-volt cable sizes differ, so check your manufacturer’s website or user manual for the correct cable size for your device. Cable calculation for your system would be to divide your Watts by 12-volts to give you your Amps and your current = Power/Volts. It is best practice to choose your cable rate greater than required to avoid surges or damage to appliances.

12-volt Accessories Available:
There are many 12-volt accessories available for your RV, off-grid project, tiny house, or Diy campervan conversion. Cable management tubing, 12-volt power sockets, connector junction boxes, vacuum cleaners, personal shavers, toothbrushes, 12-volt kitchen blenders, food warmers, one, two, and, three-way switches, many types of making and connecting tools, various types of LED display lights, LED work lamps, 12-volt external floodlights, 12-volt power winches, & 240V hook-up accessories.

12-volt Alternative Backup Solutions:
Generators, DC-to-DC Charge Controllers & Portable power banks are the recommended solutions for recharging your solar leisure battery bank when there are cloudy or short winter days.

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