isaacporras* Days Powered Without Sun: 1 Day @ Max Load | 5 Days @ Min Load
* Typical Recharge Time From Empty to Full: 3 Days of Full Sun
* 24 Foot Trailer * Sleeping Loft * About 248 Square Feet Total
* 7 X 410 Watt Solar Panels | 2872 Max Watts Total
* Can Produce 545 Watts even on a cloudy day
* 44kWh Battery Rack @ 48 Volts
* Max Continuous Load : 15kW @ 120VAC
* Average Hours of Sun Per Day Required for Max Load: 4.6 hours
* RV Water Connection and 8 Gal Point-of-Use Water Heater
* Inductive Stove Top with Range Hood and 4-in-1 microwave/oven
* 32" Shower and Choice of Toilet Style
* Generator/Grid Tie Input: Standard 50 Amp Connection
* Power Output: Standard 50 Amp Socket
Design challenges include supply chain issues, certifications, scaling up production, and cost of materials due to inflation. Plans for deployment include setting up a tiny home factory and maintaining quality control standards.
Interestingly, this value 80kWh per week (4.16MWh per year) for a person living in this tiny home seems to match what a typical person consumes from their existing power company and you can check your electric bill to see if your weekly power consumption is the same. Simply take the average monthly electric consumption and divide it by 4 weeks then divide by the number of adults living in the household. This is very close to the average per capita electricity consumption in the UK: https://www.statista.com/statistics/383633/worldwide-consumption-of-electricity-by-country/
This is a conservative estimate since this does not account for multiple occupants in the tiny home, time away from home, the newer generation of solar power equipment, or other renewable sources of power like farm animals, passive geothermal, and biogas, which significantly increases energy efficiency in the future.
Assuming the toilet is connected to a sewage, septic, or composting system, the top five most power consuming appliances are the water heater, space heater/air conditioner, the solar inverter itself, refrigerator, and a hair dryer.
Since the water heater consumes more than double the energy of the second most power hungry appliance, the water heater is the target of the most energy efficient design possible using the latest technology available. The final water heater design utilizes the smallest 8-gallon water heater tank with the highest operating temperature of 161 F then installing a thermostatic valve on the outlet, which automatically mixes with cold water to bring the temperature down to a safe 120 F. A smaller hot water tank at a higher temperature is much easier to store, insulate, and heat up with a smaller heating element over a longer period of time than a larger tank at a lower temperature. Combined with a lower flow shower head of less than 2GPM, a maximum shower time of 13 minutes can be achieved with only 8 gallons of hot water. This is a good online hot water mixing flow calculator: https://www.spiraxsarco.com/resources-and-design-tools/calculators/water-mixing/water-mixing
It is also interesting to note that the size of the battery required for 100% solar off-grid is about the same size as an electric vehicle battery. The difference is that the house battery can provide energy for cooking, showers, heating, air conditioning, lighting, working from home, food storage, washing clothes, entertainment, and powering electronics while the car battery energy is mostly used for pushing a 2,000 pound piece of metal on wheels around town. In comparison, a full high speed rail service in California would require 5.16TWh of electricity a year, which would be equal to over 1.2 million electric vehicles assuming similar battery capacity and discharge cycling as a tiny home.
https://hsr.ca.gov/wp-content/uploads/2022/09/final_EIR_MerFres_TA3_06C_EnergyUse-A11Y.pdf
In another comparison, the electric energy consumption of Bitcoin fluctuates with the price, but even in a bearish market low estimate of 45TWh per year, the energy that Bitcoin consumes could power 10.8 million tiny homes, which is enough energy to end homelessness in the United States 18 times over or power an equivalent of eight fully-built California high speed rail networks.
The other important critical part for this solar powered tiny home design is the decision to place the batteries inside the home while the inverter is outside the home. This is because the battery control circuit boards have temperature safety features built-in that will shut the system down, so the batteries must be located in a temperature controlled area. Since there are already people living in the home controlling the temperature, it just makes sense to also place the batteries in the same space. Since LiFePO4 batteries are used, it is the safest Lithium battery chemistry available and will not pose any risk in the living space. The inverter is not as sensitive to temperature and it can make annoying sounds at times, so it can be isolated outside in the outdoor closet.
For two occupants, a longer 28' tiny home trailer with 1 more solar panel on the roof would meet the extra energy requirements for full-time use.
It is also possible to daisy chain multiple Solarcycle tiny homes together to share power. For example, when one resident is on vacation, they can turn on the 240V output circuit breaker to share power with others.
This project is in the form of a tiny home, but the same calculations can work for a larger sized home if it is well insulated and ventilated with energy efficient appliances.
Estimated Total Material Cost: $70k
* FOR BEST RESULTS - * Angle solar panels directly at sun. * Make sure no shade covers any part of the solar array throughout the day. * Best times to solar charge is from 8am to 4pm in the summer and 10am to 2pm in the winter. * Daily full Load includes working on a laptop 8 hours, WiFi, cooking, hair dryer, hot 10 minute shower, 4 hours of TV, 4 hours of heater or A/C, fridge/freezer combo, washer/dryer combo unit, other kitchen appliances, and portable incinerator. * Pairing down to only essential clothing and other items will help save space. * Wool clothing will easily air dry saving energy.