Mull Renewables Hardware Hacks

This is the page holding the off grid powerplant design boards. If you ever wished you could get out of the clutches of electricity suppliers and have the time to learn, these cards are all you need to go off grid with some style. They are wholly my own design including software. The cards are each designed to perform a modular service, and are easy to interconnect, a bit like the Arduino, but much more robust. I am releasing these under the creative commons licence Attribution-ShareAlike 3.0 Unported. You may freely use share, and adapt these but not for commercial purposes. These cards can give you complete control over your energy needs, they will be fully tested with supporting documentation, software, and training. They will be used in my renewables powered sailboat Orion, and Trailer unit.

Once you have built and connected these cards to your solar PV array, you will never again need to pay for the electricity you use each day, and I intend to add more boards that allow every aspect of off grid living to be managed; including the solar haybox cooker which uses miniscule amounts of energy. The cards are designed for reliability, ease of debug and repair, and long life. They just run. You can program them with an old XP laptop cheaply available on ebay, mine cost £35

Main Processor Card

Based on the standardised 28 pin PIC processors, this card is an ultra low power consuming board, transient, and polarity protected power with multifunctional connectivity. It has been tested in the real world for 5 years now. It has a complete operating system which has run for 15 years.

It gives you a fully protected heart to your ideas, which has the capability of huge 128K programs and tons of RAM. I have configured it for the PIC 18F252 and the PIC 18F27J13, it is a wonderfully capable board you are unlikely to ever accidentally blow up with a scope probe!

80W 12-24V Maximum Power Point Tracker Card

This card pumps the power from a standard 80W 12V solar panel up to 24-32V to charge a pair of 12V lead acid batteries in series. Using this arrangement you can power second hand 700W APC UPS Inverters that are still available off ebay for peanuts. These inverters make 240V AC from 24 VDC. The reason you want to use this card is because it maximises the efficiency of the solar panel. Direct connection of a solar panel directly to a battery can result in huge losses because the optimum power point of the panel does not match the battery state. The trackers are fully transient protected against lighting or EMP damage, and can equalise.


Multifunctional I/O relay card with 16x2 LCD interconnect, with high res ADC, RTC, and temperature sensor.

This I2C daughter card controls the switching of an APC UPS on and off by simulating button presses on the front panel. In addition it can connect to a 16 x 2 44780 LCD, and underboard has a DS1629 RTC temperature sensor and alarm, and MPC 3422 18 bit ADC for current sensing of the MPPT trackers. The card runs off the I2C bus of the CPU board and is based on the PCF8574A addressable I/O expander, whose interrupt can be connected to the CPU card.

Multifunctional I/O relay card with 16x2 LCD interconnect,with high res ADC, RTC, and 8 galvanic isolated inputs

This I2C daughter card is designed to allow you to monitor switch closures in a way that bypasses ground noise and galvanic issues. By DC isolating these you can be certain of clean detection of the real world without noise issues, and more importantly avoid lightning or EMP induced damage. The opto isolators used will pop in worst case and are easily replaced.

Multifunctional I/O relay card with 16x2 LCD interconnect,with high res ADC, RTC, with 8 high current protected drivers

This I2C daughter card can drive (sink) through fusistors about 8 x 10A of power, making it very useful for driving fans or lights, with low switching noise.