Transportable Solar-Electric System for a House or Cabin (Off Grid), $5200

This stand-alone 1280 W solar-electric system is optimized to effectively power a house from a relatively small photo-voltaic (PV) array (including a full-size refrigerator, microwave oven, electric heater, fans, lights, water pump, power tools, etc). One of its benefits is that within one hour you can disassemble this system and load it on a pickup truck or trailer for transportation.

It consists of:

  • four 96-cell 320 W high-voltage panels (1280 W total solar power),
  • two rotating 1-axis mounts that track the sun via manual rotation (East-West). Each mount holds two solar panels.
  • a professional 150V/60A Maximum Power Point Tracking (MPPT) charge controller, for 12/24/36/48 Vdc battery banks, with Ethernet connection to a laptop for monitoring and programming,
  • a battery bank with 28.8 kWh energy storage capacity (eight large lead-acid batteries). These batteries may be connected to operate at any bank voltage, per charge controller,
  • control software for monitoring and programming the system (installed on your laptop computer),
  • all wiring, cables, switches, fuses, etc.

Because of different and varying customer needs, the DC-to-AC inverter is sold separately. The inverter choice may be: 120 Vac single phase, 240 Vac split phase, three-phase in different voltage configurations, Pure Sine Wave, Modified Sine Wave, etc, per your needs.

This system is fully programmable via the control computer’s software. All parameters related to the battery charging phases (bulk, absorption, float, equalization) may be programmed by the user. Other programmable features include: safety disconnect/reconnect voltages, PV array operating voltages, battery voltage display thresholds, alarm notifications by email, communications network security, etc. Several programming examples containing typical system settings are included. The system’s controller may be connected to the internet via a router, and accessed from anywhere to monitor and program the system.

Using the same controller, this system is expandable to 3600 W by adding more solar panels. In this case the controller and the battery bank would be set to operate at 48 Vdc (and the inverter would be a 48 V inverter). This system is also expandable to much higher wattage (easily tens of kilo-Watts, and beyond) if more synchronized controllers with their own solar arrays or wind/hydro turbines are added, and programmed to charge the same battery bank. Multiple inverters can also be used for increased AC power output, either by operating separately to power separate branch circuits, or synchronized at the AC outputs to power the same branch circuit.

In any configuration, this system may be set up to operate at system voltages of 12, 24, 36, 48 Vdc, depending on the power needs and inverter availability. However, as in any such system, the lower the operating voltage the lower the maximum power-processing ability, for example 900 W max for a 12V system, 1800 W max for a 24V system,  2700 W max for a 36V system, and 3600 W max for a 48V system.

Essentially unlimited solar array power may be connected to the charge controller, and the controller will self-regulate to use all available power up to its power-processing limits. This feature is useful while operating on cloudy or overcast days, with partial panel shading, etc., when the solar panels typically produce a fraction of their specified STC output. Under these conditions the extra power gets fully processed in this system to make up for the loss caused by lower irradiation or reduced solar input.

The picture below shows the four 320W solar panels mounted on the two rotating one-axis frames. The frames rotate in azimuth from 90 deg vertical on one side to 90 deg vertical on the other side. They can be set with the panels in a horizontal position, and in any position on both sides of horizontal at user-selected angles.


Another picture below shows the battery bank, the eight large lead acid batteries.


This system is sold as a kit, for DIY installation, or for installation by your electrician. The final installation must be done in compliance with all the national and local electric codes.

Copyright © 2013-2017 Jack Borninski. All Rights Reserved.


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