Off-Grid Workshop
IN THIS LESSON
Please scroll down to the “DOWNLOAD PDF” buttons for the course materials.
Credits:
PDF 2: Filter Guy, Solar Engineering Consultant - EG4 and Consumers in DIY Solar Power Forum
PDF 3: https://www.etrailer.com/
Highlights:
Educate Customers on Battery System Design
Develop educational materials explaining how inverter size influences battery bank voltage and wiring requirements to help customers make informed decisions.
Stock Appropriate Wiring and Components
Ensure availability of commonly recommended wire sizes like 4-aught and compatible inverters for 12V, 24V, and 48V systems in the store.
Provide System Design Support
Offer consultation services to assist customers in selecting the right battery bank voltage and inverter size based on their power needs and solar input.
Overview
Discussion on different battery voltages and their applications in electrical systems.
Emphasis on the importance of inverter size in determining battery bank voltage.
Analysis of wire sizing and amperage considerations for various inverter capacities.
Consideration of solar input capacity in choosing battery bank voltage.
Practical recommendations for 12V, 24V, and 48V systems based on use case and component availability.
Core Insights
Battery system voltages commonly include 12V, 24V, and 48V configurations.
Overall system voltage refers to the entire battery bank voltage, not individual battery voltages.
Wiring batteries in series changes system voltage; e.g., four 12V batteries in series make a 48V bank.
Inverter size (wattage) is the primary factor in determining appropriate battery bank voltage.
Higher inverter wattage demands higher system voltage to reduce current (amperage) and allow smaller wire gauge.
Typical inverter sizes discussed: 3kVA, 5kVA, 10kVA, with corresponding current draws at different voltages.
Wire sizing recommendations are based on inverter current draw; 4-aught wire is common for 3kVA 12V systems.
Larger wire sizes (bigger than 4-aught) are expensive and mostly for industrial use.
Dual inverter systems (e.g., dual 3kVA, dual 5kVA) add complexity and wiring challenges.
Solar charge controller capacity and solar input wattage influence battery bank voltage choice.
12V systems suit smaller solar inputs (~1450W), while 24V and 48V systems suit larger solar arrays.
Component availability (inverters, DC-DC chargers) varies by voltage; 48V options are more common for high power.
Victron products are highlighted, with limitations noted for 48V DC-DC chargers.
For mobile applications with shore power limits (e.g., 30A or 50A), inverter and system voltage choices must consider breaker capacity and wiring.
48V systems are generally recommended for stationary off-grid applications and higher power needs.
12V and 24V systems are viable for smaller or mobile applications but have limitations at higher power.
Matching brands for components is preferred but sometimes not possible due to product availability.
Practical advice includes starting with inverter size, then selecting system voltage and wiring accordingly.
Trends & Patterns
Increasing inverter wattage correlates with a shift towards higher system voltages (24V or 48V) to manage current and wiring costs.
The market shows a trend of more 48V system components for high power applications.
DIY and small-scale systems often use 12V or 24V due to component availability and simplicity.
There is a growing emphasis on system design efficiency, balancing amperage, wire size, and cost.
Integration challenges arise when mixing components of different voltages or brands, influencing system design choices.
Expert Opinions
The speaker advises against using 12V systems for very high inverter wattages due to excessive current draw and wiring complexity.
Dual inverter systems add complexity and are less preferred unless necessary for very high power demands.
48V systems are considered the best choice for most stationary and high-power off-grid applications.
Using multiple smaller charge controllers in 12V systems is possible but less cost-effective than a single controller in higher voltage systems.
The speaker emphasizes practical experience from over 30,000 electrical system installations to support recommendations.
Strategic Implications
System designers should prioritize inverter size to determine battery bank voltage for efficiency and cost-effectiveness.
Selecting higher voltage systems (24V or 48V) reduces amperage, allowing use of smaller, less expensive wiring.
Component availability and compatibility must be considered early in system design to avoid integration issues.
For mobile applications with limited shore power, inverter and system voltage choices must align with breaker and wiring constraints.
Businesses selling electrical components should stock popular wire sizes (e.g., 4-aught) and compatible inverters to meet customer needs.
Educating customers on the trade-offs between voltage, amperage, and wiring complexity can improve system design outcomes and satisfaction.