These pages contain project documentation and various information sheets relating to renewable energy system design. This includes good electrical system design and installation and renewable energy resource assessment.

The information sheets have arisen from the varied projects that re-innovation has worked on, both within the UK and within developing countries. They are designed to be informative, easy-to-understand and show the practical aspects.

Sure 8x32 LED display test

Using dot matrix LED display with arduino

I am working on a project to display some text and graphics as the interface to a race timer (for the solar cars in schools project here). To do this I had obtained some 8 x 32 LED dot matrix displays from Sure electronics. I had decided to keep the development time to a minimum, … more

Measuring AC current

For a recent project I was asked to measure the current from a solar photovoltaic (PV) system. This is a typical request as knowing the current is useful for control systems and for measuring power and energy. This blog post highlights some issues and ideas for measuring current. … more

Using the AVR Dragon programmer

I have got my hands on a AVR Dragon programmer and on-chip debugger. This is a low cost unit for the ATMEL 8 and 32bit microcontrollers. I was wanting to program some ATTINY85 microcontrollers (to make TV-B-Gones for a Nottinghack workshop amongst other things). I got mine from Farnell electronics and it was around £40 … more

AVR Dragon to program Arduino Bootloader

Following on from my post about using the AVR dragon to program blank AVR ICs, here is the process of buring the Arduino bootloader code onto an ATMEGA 328P. Firstly install AVR studio 5.0, as explained in the previous post. You will also need a version of the Arduino IDE installed. This post is for … more

Wifi and Arduino test

A while ago I bought one of these kits which included an Arduino clone and a Roving Networks wifi mdule. It is meant to be the cheapest way to get the Arduino onto a wifi network and hence send data out to the world. This blog post is my notes on getting it all working … more

Pedal powered Scalextrix

re-innovation have worked with London Bike Hub on a number of projects, providing their pedal powered sound system, bubble machine and pedal smoothie machines. London Bike Hub are involved with all activities related to the promotion of cycling, including cycle training, educational workshops to get people onto bikes and bicycle maintenance. They approached us to … more

Bus Pirate

The Bus Pirate is an open source test device designed by Dangerous Prototypes. It can test a number of common protocols including SPI, I2C, MIDI etc and also works as a 40MHz frequency analyser and 1MHz logic analyser. I was recently lent a Sparkfun Bus Pirate version to have a play with. It is configurable … more

Using the DataDuino

To give an example of how easy it is to use the DataDuino, I have recently set one up on my off-grid solar power system. This measures the battery voltage and solar PV panel voltage, along with the outdoor and indoor temperatures. The voltage data will help me understand how much energy is going into … more

ATTiny with Arduino IDE

This is a post on getting the range of Atmel ATTiny microcontrollers working with the Arduino IDE. I was wanting a quick and easy way of programming smaller microcontrollers, for when the 28pin ATmega328 is just a bit too much. I looked at the range of 8-pin ATtiny microcontrollers via a comparison list here. I … more

Adding a logo to your KiCAD PCB

For PCB design I use the open-source schematic and PCB design software KiCAD. Its a great program and has gotten a lot better recently. It is unlimited in size, components and number of layers and has lots of the features of very expensive professional PCB layout software. But… there are times when its not so … more

Proportional-Integral Control

In trying to implement a battery charge algorithm I needed to use some form of control to maintain a voltage set-point. To do this with a good step-change response and stability is harder than you might think. I decided to implement a relatively simple Proportional and Integral controller to perform this task, as I have … more

Minimus AVR and Arduino IDE

I’ve been investigating using my Minimus AVR units for a number of projects, so here is a post with how I got going using the minimus AVR unit with the Arduino IDE. The Minimus AVR is a USB connected microcontroller, which uses the ATMEL 90USB192 microcontroller. This has 16kB of memory (I have a number … more

Heatsink Calculations

I’ve been designing some heatsinks for the open-source charge controller project. The circuit contains a diode and a MOSFET, which could potentially have up to 20A flowing through them. In this case they will get hot and will eventually fail. I need to ensure that they will be kept within their specific working parameters by … more

Pedal power smoothies – BMX sized!

I’ve recently finished work on another pedal powered smoothie maker. This time its a bit different: its designed to fit 20″ wheels of BMX bikes. This was commissioned by London Bike Hub (who already have a large pedal smoothie bike, pedal powered scaletrix and a pedal powered electricity generator from me). They wanted a smoothie … more

Voltage divider

Accurate Voltage Measurement

I’ve been trying to accurately measure voltage for my open-source charge controller project. This project relies upon accurate measurement of voltage as this is used to control the regulator. I have been having some difficulty getting reliable and accurate voltage measurement, so I wanted to figure out why that was. I am using a simple … more

Enable Brown-out Detect on ATTiny

Continuing the work I have been doing on the open-source charge controller project, I needed to ensure that the microcontroller reset correctly when the supply voltage drops. The charge controller is powered from the renewable energy source and so the input voltage will vary (for example on a solar PV module at night the voltage … more

PCB trace width calculator

The next step with the open-source charge controller project is to design the printed circuit board (PCB). This circuit board has specifications that it will work with up to 20A DC, hence I need to ensure that the thickness of the tracks is able to cope with this current without any problems. Here I show … more

TFT LCD display

This is a post about getting a graphical full colour LCD screen running with an Arduino. The sample screen was the ITDB02 1.8″SP unit from iTead Studios. It is based upon the ST7735 control IC which uses serial data for the display.   … more

OLED display

I recently helped fund a Kickstarter project for an Organic LED (OLED) display and breakout board. This was design and built by ILSoft, an electronics and software company based in Tyne and Wear, UK. I had been interested in using an OLED display for some time, as they have a good contrast ratio and quite … more

Voltage and Current Measurement Units

T4 Sustainability is an East Midlands based renewable energy design and installation company. Renewable Energy Innovation have worked with them a number of times on various projects. Recently they were contracted to design and install a solar PV testing rig for Coventry University. This was designed to be used to test PV modules and balance … more

Charge Controller prototype

Here are a few photos of the prototype of the open charge controller project. I have recently got the second version of the PCBs and have designed a simple case for it. I’m in the process of testing all the functions and finishing off the software algorithms for it. Its based around an ATtiny85 microcontroller … more

Protocol Specifications

A lot of the projects created here need to communicate with each other, or with other devices. In order to do this I wanted to implement a standardised communications protocol. Hence any item that is designed here at re-innovation can interface with other items seamlessly. I decided to base my communications protocol on the Lightweight … more

Fast PWM on ATTiny85

This is a post about changing the PWM frequency of an ATTiny85 which has been programmed via the Arduino IDE. I wanted a faster PWM frequency to remove audible noise on a dump load controller I had been designing. This controls an output load using PWM and a FET. This produced audible noise when running. … more

Sleep Modes on ATTiny85

When using microcontroller in battery-based applications we really need to look at current consumption. This will affect the power consumption and hence the lifetime of the device. This post shows some tests I performed to try and reduce the current consumption of an ATtiny85 AVR microcontroller using sleep modes and switching off various aspects of … more

Low-Cost Wind Datalogger

Wind speeds are very site-dependant – with topology, ground roughness and other factors affecting the local wind speed. Knowing the wind speed and frequency of the wind speed at a particular location allows us to make a more accurate resource assessment. An accurate resource assessment is required for ensuring the wind turbines are sited correctly … more

Pedal powering Cheese….

This was a project to pedal power ‘Cheese’ a theatrical adventure through the twists and turns of a system too big to fail. It turns out that theatre productions are not usually the most energy efficient performances, using high power lighting and sound rigs. This highly efficient show will be powered using human pedal power. … more

Latrine Logger Prototype

I have been working along with Nicola Greene (in conjunction with Water for People and Engineers Without Border UK) and James Fowkes (a fellow Nottingham Hackspace member) to look at the issue of data monitoring for pit latrines. A group of us had a hackday at Nottingham Hackspace to discuss the problem, look at solutions … more

Battery Monitoring Circuits

Accurately monitoring lead-acid battery state-of-charge would help with the long-term sustainability of off-grid renewable energy systems. There are a number of ready-built products already available, mainly for the recreational vehicle market (eg. boats) and are relatively high cost (too high to include within a small off-grid power supply system). There are also a number of … more

Renewable Energy Resource Monitor

Following on from the work done for the Wind Datalogger and the Latrine Logger, we are bringing these ideas together to create a Renewable Energy Resource Monitor. This is a Arduino-based data-logger which has a range of sensors which can measure different weather resources which relate to renewable energy generators. The end result is low-cost … more

Multiple Sheet Schematics in KiCAD

For PCB design I use the open-source schematic and PCB design software KiCAD. Its a great program and has gotten a lot better recently. It is unlimited in size, components and number of layers and has lots of the features of very expensive professional PCB layout software. There are times when having just one schematic … more

The Prediction Machine

The Prediction Machine is an interactive artwork which aims to engage the public with climate change issues via a fortune telling machine. Created by the artist Rachel Jacobs in collaboration with myself, Ian Jones (Sherwood Wood), Matthew Gates, Robin Shackford, Juliet Robson, Dr Candice Howarth and Dr Carlo Buontempo. I designed, built and tested the … more

Surface Mount PCBs

Following on from the surface mount reflow oven I built, I thought I would report on its performance and my experiences with surface mount devices. I had designed a relatively complex board which had a number of devices which were only available in a surface mount package. So I decided to produce this board with … more

No Weld Pedal Generator

DIY ‘No-welding’ pedal-powered generator plans

Here are full constructional plans for a do-it-yourself pedal generator, including the bicycle stand. This is designed so that there is no welding involved (as I do not have welding equipment). I have built two of these stands and they have proven to be quite reliable and robust. … more

Humidity sensors

For a new project I am looking at measuring weather data in remote locations. This is for a low-cost, low-power wind data logging unit. The main parameter to record is, of course, the wind speed and I am doing this with ten minute averages from a pulse-output anemometer. While this data is useful, it would … more

Humidity sensors part II

Following on from my previous post on measuring humidity, I decided to test another couple of humidity sensors I had lying around. These were the DHT11 and the DYPTH01B. These are both low-cost capacitive sensors and both had been obtained when I put in an order with a Chinese supply website (Sun Tek Store). Neither … more

DIY solar PV panel information

Here are collected notes and ideas on building your own solar photovoltaic (PV) panel. These come from a number of places including attending a course run by Dan Quiggin of Demand Energy Equality, web-searching, discussion with Norman Phipps of Handmade Solar and also running my own DIY PV workshop at Nottingham hackspace. I feel that … more

Minimus, Arduino IDE and USB

I have mentioned the Minimus AVR before on this blog. It is a very low-cost ATMEL micrcontroller board with a USB bootloader. This post describes using the device as a HID (Human Interface Device) such as a keyboard or mouse. A challenge was set by a friend to take serial commands and, depending upon the … more

RPM sensor

Monitoring the rotational speed of the wind turbine blades can help with power performance measurements. This post shows various techniques to measure the rotational speed of a ‘wild AC’ output small wind turbine. In this system, the wild AC is rectified into DC and either delivered to a battery or to a grid-connected inverter. The … more

8 x 32 LED display unit

I’ve been messing around with some 32 x 8 LED displays – as I have been wanting to create graphics. These LED displays are from Sure Electronics are available for around $13 and use the HT1632 LED driver IC, with an SPI-like control. I have previously used these displays for a couple of projects here … more

Pedal-powered blender

A pedal powered blender for making smoothies at festivals and events had always seemed like a great idea. It brings in a number of concepts: firstly there is the ‘we don’t need electricity for everything’ idea, secondly it helps to demonstrate the concept of power in a interesting and practical way, thirdly it helps to … more

Archived Product Details

All our kits will be sold via The Curious Electric Company from now on. These pages are for information only. Please visit our shop for up to date information or contact us to discuss your project and how we might be able to help. … more

Solar powered laptop

During 2007 this simple solar photovoltaic (PV) system has provided some of my energy needs (OK, a pretty small percentage I’ll admit). In total there are approximately 40W(peak) of PV panels. … more

Arduino and Mobile Data

I’ve been wanting to play around with sending data via a mobile SIM card and, after needing to do it for another project, here is a short post on my attempts at getting it all going. I used an off the shelf GSM/GPRS module (the SIM900). I tried this using both the Arduino Uno and … more

Solar cooker ideas

In response to a friends challenge to make a solar cooker and prove it would work in the UK, the solar cooker shown below was built. Only scrap materials have been used, mainly based upon a piece of plastic mirror found in a skip … more

DIY solar PV system

Here are some details on the prototype for the ‘build your own’ solar power system I ran as a workshop at the Nottingham hackspace. I’m pretty pleased with how it looks. Basically it is a micro solar PV (photovoltaic) system, which includes a 10Wp solar panel, charge regulator and voltmeter, all encased in a laser … more

Which micro-controller to use?

“There are so many micro-controllers. Which one do I choose?” This is common question within the world of electronics design. Here I list the main contenders and their development tools. I’m trying to give advantages and dis-advantages, but these could be very different for different projects. I’m also listing the main development boards and which … more

Pedal power charge regulator

Pedal power is a great, inter-active demonstration of power generation and consumption. Building your own pedal generator is also an amazing learning experience. There are a number of plans and designs around for the generator and stand (check out our own here), but information about the electrical systems is usually lacking. Here is a full … more

Arduino and LED Matrix Display

I was asked to build a BIG LED display for a pedal powered cinema for a film group in Brussels (more about that in another post). I found these huge displays from Embedded Adventures and had wanted an excuse to have a play with one of them for a while. This is a post about … more

Solar car race timer

re-innovation were behind the original solar car kits used by reaction education. They supply renewable energy and engineering activities for a wide range of educational events. Their main activity is to design, build and race a model solar powered car. The kit includes a number of solar panels, motors, wheels and gears along with a … more

Remote display for power and energy monitor

We already supply the pedalog – a power and energy monitor especially for pedal powered generators. It also works with other forms of energy generation such as solar and wind and also energy consumption of DC loads. One issue was displaying the data so that it is interesting and informative. One customer (Magnificent Revolution) asked … more

Measuring temperature

Measuring temperature is incredibly useful. It is probably one of the most important environmental variables and there are a wide range of devices to do this task. I have recently had a number of projects which require accurate temperature measurement and storage, including a data acquisition system to measure hot water usage and a monitoring … more

Designing Laser-Cut Enclosures

In this post I’m documenting my process for designing enclosures for some of my projects. This is the design process I use to produce bespoke enclosures with cut-outs, using the laser cutter at Nottingham hackspace and 3mm plywood. In this example I’m designing the enclosure for a power monitor with a large 7-segment LED display. … more

Expanded scale voltmeter

While working on a wind/PV system in a remote area of the Philippines the need   for a voltmeter which showed the system (battery) voltage in detail arose. Only analogue V and A meters were available in the local town. This simple design explains in detail how to convert a low range ammeter into a voltmeter … more

Caravan solar PV system

A friend has been using a beautiful 50’s caravan to head to festivals and sell efficient outdoor cooking apparatus, through his company He had already installed a 12V lighting system and a deep cycle battery. This year he planned on expanding his system and incorporating solar PV power. Already a very low user of … more

Pedal Power for Magnificent Revolution Australia

Re-innovation was asked by Magnificent Revolution to help build an 8-bike pedal powered generator for use over in Australia. Greer Allen has started up Magnificent Revolution Australia and has been working with Magnificent Revolution in London. She will be taking the generator over to Australia for a cinema event in Sydney. She came up to … more

Displays for pedal power demonstrations

I have recently finished a number of display and control units for pedal power demonstration systems. These projects have been in conjunction with Magnificent Revolution, who have been providing the actual pedal generators. The systems consist of: a shunt regulator (rated at 200W) to dump any excess power a LED bar graph display as a … more

Electrical system design guide

This was a practical guide produced while working for SIBAT, an NGO working in the Philippines, on a 1kW wind turbine off-grid system for remote community electrification. This work was part of a one-year placement in the Philippines funded by Engineers Without Borders UK. … more

Pedalog – The pedal power monitor

Note: This has been depreciated and is not available any more. Please see the new version of this device. There are many pedal power generating devices around – from recharging batteries to powering sound systems and cinemas. These systems are great interactive exhibits for people to get a physical feel for the power and energy … more

Design documents for International Development projects

Here are a number of documents which were produced as part of my work at SIBAT, a Filipino NGO working in remote rural development. This placement was funded through Engineers Without Borders UK. This work covered project management, resource assessment, practical electrical and mechanical design. It has been written specifically for the Philippines, but most … more

Solar car kits

Re-innovation were behind the original solar car kits used by reaction education. They supply renewable energy and engineering activities for a wide range of educational events. Their main activity is to design, build and race a model solar powered car. The kit includes a number of solar panels, motors, wheels and gears along with a … more

Remote Power Display

Magnificent Revolution run pedal powered cinema and music events. I have worked with them extensively, mainly on their electrical systems. They have a  8 and a 20-bike pedal power unit which can generate quite a bit of power (around 2kW with 20 riders). They wanted a display to give feedback on the amount of power … more

Fibreglass wind turbine blades

This was a practical guide produced while for SIBAT, an NGO working in the Philippines, on the construction of fibre-glass wind turbine blades for a 1kW wind turbine. This work was part of a one-year placement in the Philippines funded by Engineers Without Borders UK. … more

Jo Fairfax Studio – Motor controller

I’ve been working with light artist, maker and NESTA fellow Jo Fairfax, (of Jo Fairfax Studio) on an interactive wall prototype. He needed to have control over loads of motors which all move circular disks a set distance. I designed a stepper motor controller unit to control up to 12 motors. These can be repeated … more

DC current measurement

A number of the projects we are involved with require accurate monitoring of DC currents. Here we explain the numerous techniques for measuring DC current flowing in a line, highlight some of the multitude of integrated circuits available and list the pros and cons of various techniques. This is an on-going work – please post … more

LED display unit

For a couple of recent projects we have been asked to provide interesting and informative display units. We decided to build a unit which can be used in a number of different applications. It was designed to look good, be able to show graphics and text, have a couple of switch inputs and be configurable … more

Pedal Powered DVD

I’ve just put the finishing touches to a pedal-powered DVD player which will be installed at a Stubbington Study Centre in Hampshire. This pedal generator is designed to be entertaining and fun, while also being educational and robust. There are three parts: Pedal generator – based on an exercise bicycle Large bar graph display DVD … more


Its very difficult to explain the concepts of power and energy. People often ask me “Can I power my kettle with that?”. So to try and put the energy in a cup of tea into perspective I built the ‘Cuppa-meter’. The ‘Cuppa-meter’ shows a cup of tea which lights up as the energy required for … more

Wind turbine electrical system design guide

This was a practical guide produced while working for SIBAT, an NGO working in the Philippines, on a 1kW wind turbine off-grid system for remote community electrification. This work was part of a one-year placement in the Philippines funded by Engineers Without Borders UK. … more

Home-built solar thermal panel

This page describes the construction of a solar thermal collector. This integrates into a hot water system and ought to help reduce the boiler requirements through the summer months. This has been built mainly using scrap and recycled components. … more

Battery monitor

“Improving the long-term sustainability of off-grid renewable energy systems in developing countries.” A monitor for battery based renewable energy systems has long been on the to-do list for re-innovation. This page describes why such a monitor would be useful and introduces the design. … more

ACS758 Current Measurements

I’ve been designing a breakout board for the ACS758 hall-effect current sensor. The first few prototype boards came in and I decided to give them a quick test. The results were not quite as I expected so I thought I’d put write about them here, for others that might be using this IC. These current … more

Making Printed Circuit Boards

Recently I produced a workshop on making your own printed circuit board for a Hack Space in Nottingham I am involved with. A Hack Space is an open workshop where people can use collective tools and share ideas, knowledge and work on group projects. As I had written the presentation, I thought it would make … more

DataDuino – Arduino data acquisition unit

This data acuisition (DAQ) unit kit is designed to be robust and configuable but relatively simple. It is based upon the Arduino platform (using the Uno bootloader). It stores data to an SD card and uses a real time clock for accurate timestamping. The fastest resolution is 1 second sampling. Data acquisition is always useful to … more

PV I-V Curve Tracer

It is very useful to measure the current against voltage characteristic for a solar photovoltaic panel. Here I shown how I built an I (current) against V(voltage) curve tracer for solar photovotlaic panels which is battery powered and can be used ‘in the field’. The output is displayed on a full colour LCD display, along … more

Pedal power for Nottinghamshire Healthcare

There has been a spate of pedal power projects in the re-innovation workshop recently. This post shows one recently built for Nottinghamshire Healthcare. The pedal generator was designed as a challenge with a twenty second test to see the amount of energy the cyclist can generate. It also needed to be relatively portable (to fit … more

Micro-hydro electronic load controller project

Last year, re-innovation had two students, Shoan Mbabazi and Jon Leary, working on a project I had proposed for a electronic load controller for micro-hydro systems. These students were from the Sheffield University e-futures PhD course and completed this work as a ‘mini’ project. … more

Solar PV design worksheet

This is a simple design worksheet for stand-alone solar PV systems. It explains the design process and explains some of the practicalities of building a system. This document is open source. … more

Demonstration Equipment for Engineers Without Borders

Renewable Energy Innovation was recently asked to build an exhibition stand and equipment for Engineers Without Borders UK. They wanted the equipment to work with a wide range of ages and at various events. We were commissioned to build a pedal generator with sound system, a rope-washer pump and a small solar PV system. We … more

Voltage measurement

A number of our projects require accurate monitoring of voltages. Here we explain the numerous techniques for measuring voltages, both DC and AC, highlight some of the multitude of integrated circuits available and list the pros and cons of various techniques. To measure power (and hence measure energy) within electrical systems, we need to know … more

DataDuino – Serial

I needed a data logger which could take a stream of serial data and record it onto an SD card. To do this I based the hardware on the DataDuino and changed the microcontroller code. This is an overview of the idea and the arduino code required to implement it. This was designed to work … more

Engineering in Development ‘Energy’ Book

Over the past two years a number of people have been working on a series of books for Engineers Without Borders placement volunteers. These books are designed to cover the basics of the theoretical, practical and social aspects of doing engineering projects for devlopment. They are meant as a basic guide, a collection of case … more

Latrine Logger Unit

The Latrine Logger was developed for Water For People. Water For People is an international non-profit working across 9 countries to bring safe water and sanitation to 4 million people. Water for People want to see communities break free from the cycle of poverty and spend time growing, learning, and thriving, instead of walking for … more

Renewable Energy Kits for Schools

We were asked by Nottingham City Council to design and produce a selection of renewable energy demonstration kits for use with school groups of various ages. They needed equipment which could be easily assembled and taken apart, but were still configurable to a number of different designs. These are to be used as part of … more

Battery worksheet

This is an information and operation and maintenance worksheet for lead-acid batteries. It covers battery basics, the various types of batteries, battery safety and how to measure state of charge. This document is open source. … more


Solar PV lanterns

A report written for Digital Campus which reviews a number of solar PV lanterns with a view to deployment in Ethiopia. This report was written to look at using solar PV lanterns to recharge smart mobile phones in remote locations. … more

Open Charge Regulator

These articles all relate to the open-source charge controller project. We cover the hardware and the software and give a full design for a 12/24V DC 20A charge controller which can be used for solar, wind, hydro or pedal power applications. … more