Challenges in Sustainability | 2014 | Volume 2 | Issue 1 | Pages 18‒27

DOI: 10.12924/cis2014.02010018

Research Article

Mobile Open-Source Solar-Powered 3-D Printers for

Distributed Manufacturing in Off-Grid Communities

Debbie L. King

, Adegboyega Babasola

, Joseph Rozario

1,2

, and Joshua M. Pearce

1,2,3,*

The Michigan Tech Open Sustainability Technology Lab, Michigan Technological University, 601 M&M Building,

1400 Townsend Drive, Houghton, MI 49931-1295, United States; E-Mail: [email protected] (DLK),

[email protected] (AB), [email protected] (JR), [email protected] (JMP)

Department of Electrical & Computer Engineering, Michigan Technological University, 601 M&M Building,

1400 Townsend Drive, Houghton, MI 49931-1295, United States

Department of Materials Science & Engineering, Michigan Technological University, 601 M&M Building,

1400 Townsend Drive, Houghton, MI 49931-1295, United States

* Corresponding Author: E-Mail: [email protected]; Tel.: +1 9064871466

Submitted: 27 May 2014 | In revised form: 25 August 2014 | Accepted: 28 August 2014 |

Published: 30 September 2014

Abstract: Manufacturing in areas of the developing world that lack electricity severely restricts the

technical sophistication of what is produced. More than a billion people with no access to electricity

still have access to some imported higher-technologies; however, these often lack customization and

often appropriateness for their community. Open source appropriate technology (OSAT) can over-

come this challenge, but one of the key impediments to the more rapid development and distri-

bution of OSAT is the lack of means of production beyond a specific technical complexity. This study

designs and demonstrates the technical viability of two open-source mobile digital manufacturing

facilities powered with solar photovoltaics, and capable of printing customizable OSAT in any com-

munity with access to sunlight. The first, designed for community use, such as in schools or maker-

spaces, is semi-mobile and capable of nearly continuous 3-D printing using RepRap technology,

while also powering multiple computers. The second design, which can be completely packed into a

standard suitcase, allows for specialist travel from community to community to provide the ability to

custom manufacture OSAT as needed, anywhere. These designs not only bring the possibility of

complex manufacturing and replacement part fabrication to isolated rural communities lacking

access to the electric grid, but they also offer the opportunity to leap-frog the entire conventional

manufacturing supply chain, while radically reducing both the cost and the environmental impact of

products for developing communities.

Keywords: Appropriate Technology; Distributed Manufacturing; Open Source Hardware;

Photovoltaic; Solar Energy; 3D-Printing

under a Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/).

1. Introduction

Modern energy access is still far from universal, as 1.4

billion people lack access to electricity [1], which di-

rectly contributes to multidimensional poverty through-

out these regions [2]. Although two-fifths of South

Asia's population, primarily living in rural areas, have

no access to the grid, more than three quarters of the

population of Sub-Saharan Africa (587 million people)

in both rural and urban areas are without electricity

[3]. This situation appears to be static as rural elec-

trification is a major challenge [4] and as the Inter-

national Energy Agency (IEA) estimates that if rural

electrification continues at the present rate, electricity

access will only keep pace with population growth

until 2030 [1]. Although some manufacturing occurs in

communities without access to electricity, the technical

sophistication of what is produced is limited. People

with no access to electricity still have access to some

higher-technologies, which are imported and lack all

customization and often appropriateness for the

community. Considering only energy-related devices,

for example, throughout the developing world there are

broken windmills and micro-hydropower installations,

empty biogas pits, rusting charcoal kilns, and unused

solar cookers [5] or tractors and water pumps in poor

condition [6]. Often the local failure of such tech-

nologies, which are employed in many communities, is

the lack of appropriateness for a specific community

(e.g. difficulties in access to parts and capacity to

perform repairs, evolutionary capacity of the tech-

nology, predetermining risk factors) [6‒8]. Thus there

is a need to ensure appropriate technology (AT) is

used, this can be defined as those technologies that

are easily and economically put to use from resources

readily available to local communities, whose needs

they meet [9]. The technologies must also comply

with environmental, cultural, economic, and educa-

tional resource constraints in the local community [9].

Earlier definitions of AT have recently been extended

by Sianipar et al. to include technical, economic,

environmental, social, cultural, judicial, and political

specifications [8]. To meet these requirements the

diffusion of information technologies (e.g. cell phones

and the Internet) has enabled a commons-based open

design or 'open source' method to accelerate

development of AT [10‒12]. In parallel to the open

source movement in software, open source ap-

propriate technology (OSAT) is gaining momentum as

it allows technology users to be developers simul-

taneously and share the open "source code" of their

physical AT designs, and to use this ability as a

science and engineering education aid [13‒20]. OSAT

is AT that is shared digitally and developed using OS

principles. Thus, rather than computer programs, the

"source code" for AT is material lists, directions,

specifications, designs, 3-D CAD, techniques, and

scientific theories needed to build, operate, and main-

tain it. One of the key impediments to the more rapid

development of OSAT is the lack of means of pro-

duction of open source technologies beyond a specific

technical complexity.

This barrier is being challenged by the rise of open

manufacturing with open-source 3-D printers [21],

affordable versions of which are capable of replicating

any three dimensional object in a number of polymers

and resins [22‒25]. The most striking of these 3-D

printers is the RepRap, so named because it can fab-

ricate roughly half of its own components and is thus

on the path of becoming a self-replicating rapid

prototyper [23‒24]. Recent work has shown enormous

potential for open-source 3-D printers to assist in

driving sustainable development via digital fabrication

and customization [26]. For example, there is cur-

rently a collection of open source designs useful for

sustainable development [27] including peristaltic

pumps, hemostats, and water wheels on Thingiverse,

a repository of digital designs of real physical objects

[28‒30]. Most importantly RepRaps allow users in any

location the ability to custom manufacture products

that meet their own needs and desires.

In order for rural communities to have access to

the benefits of 3-D printing of OSAT they will need

electric power from locally available renewable

resources such as solar photovoltaic (PV) technology

which converts sunlight directly into electricity. PV has

already been shown to be a technically viable,

environmentally benign, socially-acceptable and in-

creasingly economical method of providing electricity

to both on grid and remote communities all over the

world [31‒37]. Solar PV-generated electricity is par-

ticularly well suited for small scale off-grid applications

because of the relatively modest power draws of open-

source 3-D printers, and it will be addressed here.

This paper provides a description and analysis of i)

mobile community-scale and ii) ultra-portable open-

source solar-powered 3-D printers including component

summary, testing procedures, and an analysis of

energy performance. The devices were tested using

three case study prints of varying complexity appro-

priate for developing community applications, while

measuring electricity consumption. Results of this

preliminary proof of concept and technical evaluation of

the use of solar PV to power mobile RepRaps for

distributed customized manufacturing are evaluated

and conclusions are drawn.

2. Methods

2.1. RepRap Background

RepRaps can currently print with ABS, poly-

caprolactone, polyactic acid (PLA), and HDPE among

other plastics and generally cost between $30‒50 kg

‒1

[23,25]. PLA, which is used here for tests, fits the

definition of AT as it is derived from renewable sources,

is recyclable and bio-degradable. In addition, printed

PLA with a RepRap has been shown to be as strong as

commercial prints [38]. The extruder intakes a

filament of the working material, heats it, and extrudes

it through a nozzle. The printer uses a three co-

ordinate system, where each axis involves a stepper

motor that makes the axis move and a limit switch

which prevents further movement along the axis. The

printing process uses sequential layer deposition,

where the extruder nozzle deposits a 2-D layer of the

working material, then the Z (vertical) axis lowers,

and the extruder deposits another layer on top of the

first. In this way it can build three dimensional models

from a series of two dimensional layers. It should be

noted that other heads are under development that

would allow for a greater range of deposition

materials [23,25,39‒42]. It should be pointed out

here that any of the RepRap class of 3-D printers can

be deemed appropriate for this application. The

FoldaRap was chosen as the final prototype here as it

is commercially available. It is a RepRap that folds

down, as its name implies, into a small footprint and

is thus relatively easy to transport. Today there are

many easily transported RepRaps.

2.2. Power Requirements

Here only standard RepRap solid polymer filament

extruders are considered. Their power requirements

based on a number of options are shown in Table 1.

The total power necessary will also be determined

by the processing options as shown in Table 2. Power

was measured with a multimeter (± 0.2%).

Table 1. Power requirements of RepRap variants.

RepRap Name Power printing (W) Power heating (W) Time (min

−1

LulzBot Mendel 35 W 140 W 1‒2 min

−1

Prusa Mendel 37 W 130 W 1‒2 min

−1

FoldaRap 40 W 135 W 1‒2 min

−1

Note: it should be noted that the tests in this study were performed on a heated

bed to represent a worst case scenario. The heated bed can be avoided by

printing on blue painters' tape with PLA or with a glue-stick on glass, but such

appropriate surfaces have not been found for all plastics.

Table 2. 3-D printer processing power requirements.

Option

Price Power (W) Operating

System

Notes/References

Raspberry

Pi [43]

$35

(+monitor)

3 W

(+monitor

draw)

Linux

Pros: very inexpensive, large online community support,

RepRap software available on Linux

Cons: potentially long delivery times

APC 8750

[44]

$49

(+monitor)

13 W

(+monitor

draw)

Android

2.3

Pros: larger processor than Raspberry Pi,

Cons: no available software, would have to write new

program, not yet readily available, high power

consumption

Efika MX

Smartbook

[45]

$199 3 W‒6 W Linux

Pros: runs Linux, battery life of up to 7 h so no extra

power draw, Wifi & 3G for downloading new designs,

lowest cost for highest functionality

Cons: higher cost

Control

through cell

phone via

Bluetooth

[46]

$29 (with

existing cell)

1 mW‒5 W Android

Pros: cell phones widespread, "cool" factor

Cons: current software needs improvement, can only

print designs already in hand

Use only an

SD card slot

[47]

$35 0 W N/A

Pros: ultra low power, very low cost

Cons: can only print designs already in hand, no

community design

Tablet $150‒500 7.5 W‒10 W Varies

Pros: no extra power draw on system, readily available

Cons: higher cost

Option

Price Power (W) Operating

System

Notes/References

OLPC [48] $100‒200 2 W Linux

Pros: large user community, already scaled in developing

world

Cons: expense, difficulty running some software

2.3. Designs

Here two types of designs are considered: i) mobile

community-scale and ii) ultra-portable open-source

solar-powered 3-D printers.

2.3.1. Community-Scale Mobile 3-D Printing

The community-scaled device is designed to be appro-

priate for a school or a community center that enables

many shared users in a community to utilize the equip-

ment. The first portable solar powered RepRap was a

Mendel variant using off-the-shelf components [49] and

running RAMPS1.3 with an SD card add-on which

allowed it to save power by printing without a com-

puter connection. This system was designed for heavy

usage. The 2 x 220 W PV panels, and 4 x 120 Ah

batteries give the user 35 hours of printing with a

single charge. The system uses an inverter to convert

the DC energy from the PV and batteries to a standard

AC signal. A standard power bar can be hooked up to

the inverter, so it can run/charge multiple laptops or

printers at once. The frames of the solar panels are

reinforced and hinged together so that the faces of the

PV modules fold together to prevent damage during

transport. There are adjustable, drop-down legs affixed

to the modules, so they can be angled accordingly for

maximum sun exposure. The community-scale

PV+RepRap system is shown in Figure 1a and the

design schematics are shown in Figure 1b. The complete

bill of materials and assembly is documented here in

[50].

Figure 1. a) Community-scale PV-powered open-source RepRap 3-D printer system for off-grid community

use and b) the basic schematic design. The PV are connected in parallel; a combiner box is used to combine

and drive the DC supply towards a 30 A charge controller, which maintains the controlled charging and

discharging of the batteries. The batteries are connected in two parallel lines with each line containing two

unit cells in series. During charging periods four 120 AH batteries are fed DC current while discharging

continues to power the RepRap and the laptop through a DC/AC inverter.

2.3.2. Community-Scale Mobile 3-D Printing

An ultra-portable open-source solar-powered 3-D printer

has also been designed. This system can be easily

transported in a suitcase and is intended to provide

complete mobility so as those visiting an isolated

community (e.g. doctors) can bring it with them to

print necessary products on site in the field. Although

not solar powered, a team from MIT has already re-

ported on developing a suitcase 3-D printer [51] and

there are other portable 3-D printers currently on the

market, including Printrbot Jr (v2), Portabee, Bukito

Portable, Taz, Tobeca (which comes in a case) and the

Foldarap. Here the ultra-portable system is based

around the FoldaRap shown in Figure 2a. It is a RepRap

variant, designed by French engineer, Emmanuel Gilloz

[52]. The FoldaRap is built on an extruded aluminum

base that is designed to fold into a 350 x 210 x 100 mm

frame. The ultra-portable solar-powered suitcase 3-D

printer is shown packed and deployed in Figures 2b

and c, respectively. The design schematics are shown

in Figure 2d.

Figure 2. a) Foldarap, b) ultra-portable PV-powered open-source suitcase Foldarap 3-D printer packed, c)

deployed for printing, and d) the circuit diagram. An ATmega328 based Arduino Uno microcontroller board is

employed to control the charging unit. A current sensor, a temperature sensor and a shunt circuit are

provided to keep records and avoid unwanted damage to circuit components. A 16 x 2 LCD display is used to

monitor mode of operation. No DC/AC inverter is included; instead a DC/DC charge controller is used. The

charge controller follows the voltage divider rule in order to control the supply voltage, and feeds steady

current to the Foldarap.

The Efika MX Smartbook, an 'ultra-portable' notebook,

was chosen to control the printer. Its power runs at an

average of 3 W, compared to the standard 60 W from

other commercial notebooks. The Smartbook's battery

can easily last 7 hours on a single charge. Running the

printer off from an SD card was considered, but in this

case only parts that were already stored on the SD

card would be printable. To ensure new parts could be

designed and printed on site, a computer was necessary.

Although the Smartbook was chosen for this project, it is

not considered a must-buy component if the builder

already has a laptop with sufficient battery life.

To achieve full mobility in this model light-weight,

semi-flexible PV modules were used. At 0.95 kg a

piece, these modules greatly reduce the size of

component that comprises the largest footprint on the

community-scale model. The PV modules are com-

prised of high-efficiency mono-crystalline silicon cells.

The bulk and weight are reduced by placing the cells

on an aluminum backing, and coating them with a

clear gel, replacing the traditional large aluminum

frame and glass panel front. This system uses five 20

W modules, to give 100 W at just over 10 lb. The

modules are mounted on a durable nylon fabric enclo-

sure to prevent damage during transport.

The other main weight reduction from the com-

munity model is in the batteries. Lithium-Ion batteries

are used in the portable model for a high storage

density in a lightweight package. Although there are

denser battery chemistries emerging on the market,

Li-ion best fits the goal of a low-cost system. This

system uses four 14.8 V 6600 mAh laptop batteries. An

inverter was not used in this system, as multi printer/

laptop functionality was not required. The circuit is

designed to solely run the printer, which requires

12‒30 VDC. The complete bill of materials and

assembly instructions are available at [53].

2.4. Measurements and Case Study Designs

The rate of battery charging with the PV monitored and

correlated with detailed methods that had previously

been used to determine solar flux using Open Solar

Outdoors Test Field equipment and systems [54] and

the state of charge of the battery were measured.

Three representative designs were used for testing, as

shown in Figures 3a, b and c: 1) avocado pit germi-

nation holder [55], 2) cross tweezers [56] battery

terminal separator [57]. The latter was used in the

construction of the ultra-portable solar-powered suit-

case printer from Figure 2. The volumes of plastic

used were 8.96 cm

, 3.47 cm

, 6.91 cm

respectively.

All of the prints were downloaded from Thingiverse

under CC-BY or public domain licenses, a repository of

open source designs that currently with over 455,000

designs and is growing exponentially [58], and were

chosen from a selection of designs with the OSAT tag.

It should be pointed out here that in general

Thingiverse licenses would not offer any application

problems in development. The one potential exception

is creative commons non-commercial licenses, which

could still be printed by community members although

they could not be sold. The prints were chosen for

varied print difficulty, times and volumes. The cross

tweezers being one of the smaller end of expected

print times, and the battery holder being a standard

print. The cross tweezers require a fine enough

resolution to test the accuracy of the printer. The

following slicer settings were used for the exper-

iments: 2 perimeters, 4 horizontal shells (2 top, 2

bottom), 35% infill, 1.7 mm PLA, and 200° C for the

hotend and 55° C bed temperatures, respectively.

Figure 3. OSAT printed on the ultra-portable PV-powered open-source suitcase Foldarap 3-D printer

a) avocado pit germination holder, b) cross tweezers and c) battery terminal separator.

3. Results and Discussion

The three case study prints were successfully printed

on both device designs and example prints are shown

in in Figure 3. The size of the battery bank in the first

design ensured that hours of continuous printing would

be available to a community every day there was

adequate sunlight. The much smaller battery bank

needed for ultra-portability in the second design,

however only enables a few prints per day on one

charge. The actual parts able to be printed are deter-

mined the solar flux availability, the fill density and

slicing settings, and the size and geometric complexity

(more complex parts take longer and use more en-

ergy to print as the head moves without printing).

Table 3 summarizes the state of charge of the bat-

teries and print time on the ultra-portable printer from

Figure 2. The heated bed and extruder only took an

average of 2 minutes to get to target printing temper-

atures on the suitcase printer. Once printing, an

average of 40 W was used, decreasing the expected

amount of energy use and increasing the length of time

the batteries can last on a single charge. The cross

tweezers came out with a slight warp, as one end

started lifting from the bed during the print. This might

have been prevented by using a 60° C bed temper-

ature rather than the 55° C that was used.

Table 3. Print time and change in charge state

of test case study 3-D prints.

Case Change in State

of Charge in

Percent

Print Time

(min)

1 Avocado Pit

Germination

Holder

18.1 49

2 Cross-Tweezers 12.9 34

3 Battery

Terminal

Separator

17.5 50

The results of this study are applicable to any off-

grid community in the world with access to sunlight.

Both the community-scale and individual suitcase por-

table PV-powered RepRaps were found to be functional

and viable for digitally fabricating custom OSAT on

location. The ability to easily fabricate custom and

complex parts or products at exceptionally low-cost

offers people anywhere in the world the ability to print

themselves out of poverty as they can print items to

meet their own needs, those of their community, and

export items to sell [58]. As the RepRaps are capable

of printing both their own components for replace-

ment and are able to upgrade themselves as the

global community improves the design, RepRaps have

an extended life cycle and are appropriate for most

communities.

The related work with RecycleBots, which turn

waste plastic into 3-D printing filament, can be viewed

as a major enabling technology as it allows local

materials to be used in the production of high-value 3-

D printer parts, with lower costs and less envi-

ronmental impact [59‒63]. Plastic waste is common in

many developing communities [64,65] and informal

waste recycling is sometimes conducted as an

economic activity [66]. ProtoPrint in India is already

using waste pickers to recycle plastic into 3-D filament

as part of a social entrepreneurship program. Similar

efforts are underway with the Ethical Filament

Foundation and Plastic Bank's social filament program.

For regions, with no access to waste plastic, further

work is needed in biopolymer reactors to produce PLA

from agricultural waste. Similarly, access to the elec-

tronics in parts of the developing world may be lim-

ited. Thus, there is a generalizable risk of repeating the

past problems with broken equipment meant for devel-

opment (e.g. pump parts) by creating a new problem

of broken 3-D printers. Future work is needed in

developing RepRaps capable of fixing and printing

electronics components. It should be pointed out here

that this is not a complete solution, but a path towards

sustainable development that is still under construction.

The initial costs of the community and suitcase

systems as designed here were $2,500 and $1,300

respectively. These costs are still substantial, partic-

ularly for the majority of the developing world. These

were prototypes and the costs of the systems can be

expected to drop considerably for any replication of

the systems for two reasons. First the cost of PV has

dropped from the $1.59 W

−1

for which the community

panels were purchased and $1.90 W

−1

for the suitcase

panels to under $0.65/W for PV on the international

market. Similarly, the cost of the open-source 3-D

printers has been reduced from the start of this study

at $800 and $600 for the Mendell RepRap and

Foldarap to currently about $550 for a Michigan Tech

HS Prusa RepRap design [58] and under $500 for a

MOST Delta RepRap [67]. Both of these major costs

appear to be able to continue to fall. The value of

owning or having access to a printer is also increasing

exponentially along with the number of open source

designs—as producing only 20 common objects with a

RepRap in 25 hours of printing at home could save

consumers $300‒$2000 [58]. It should be pointed out

that this study [58] is for wealthy developed countries.

Most of the products printed are not available in areas

of the developing world and of questionable utility for

sustainable development. For developing communities,

printed items that bring high value would need to be

identified and designed. In addition to the high

economic return from deploying PV+RepRap systems

for distributed manufacturing, there are also substantial

reductions in the environmental impact of

manufacturing using this process rather than standard

manufacturing [60‒62].

Both RepRaps and Recyclebots are open-source

technologies where hundreds of people throughout the

world are collaborating to rapidly improve the tech-

nology and provide an incredibly fast growing selection

of products to print with them. This provides the po-

tential of a major paradigm shift in how industry works,

which encourages local and even home-made manu-

facturing of a rapidly increasing selection of highly

sophisticated and valuable products. These tech-

nologies and the open source paradigm hold the

promise of creating enormous wealth for those in

developed and developing communities. Perhaps the

most immediate change for the developing world will

be access to high-quality customized scientific equip-

ment at unprecedented low costs (e.g. reduction by a

factor of 100 in the costs of lab supplies and instru-

mentation) [15,16]. As this becomes commonplace

there will be an accelerating positive feedback loop—

the more scientists participate the faster technical

problems will be solved and the more value will be

created for everyone.

4. Future Work

There are several areas of future work that need to be

addressed. First, continual reductions in the energy

consumption of RepRaps will reduce the size and cost

of the PV and battery storage systems for both designs.

There has been preliminary work into printing with

either a variable area heated bed or printing without a

heated bed; the heated bed is the system's major

energy draw and needs to be considered in more

detail. In addition, a reduction in energy use is possible

through the removal of all AC-DC conversions by

avoiding standard computer power supplies. The de-

sign methodology used here was not formalized and

thus the overall design can be improved in the future

by following focused design methodologies such as

Ecodesign [68,69] or Design for Sustainability [70] and,

rather than using the PV-powered RepRap as only a

means to manufacture AT, begin to specifically design it

as AT itself [71].

This study should also be repeated with recycled

waste plastic as several commercial RecycleBots are

maturing and the concept of ethical filament is

expanding worldwide. The RecycleBot and accom-

panying shredder/grinders will also need to be adapted

for off-grid use with PV power. There is a large

collection of designs and the beginnings of open-source

digital OSAT designs, but far more work is needed to

have printable designs to meet all of the needs of the

world's people. Future field work could interview

people living in a wide range of developing com-

munities to find out what the most valuable and

relevant OSAT prints are in different geographic

regions. Considerable work is needed here, but it is

also possible for relatively modest contributions of

CAD for OSAT to have a major impact on communities

all over the world. This work is now being completed

largely by volunteers and hobbyists within the 'maker'

movement. However, there is also a business op-

portunity for companies to profit from an open-source

hardware paradigm paralleling the open source soft-

ware movement that has led, for example, to RedHat,

which is a $1 billion software company that distributes

free software. In particular, companies that sell

consumables or 3-D printer components, such as hot

ends, should consider open-sourcing the designs for

the products that drive the demand in the consum-

ables and move them into new markets. Finally, in

order to minimize costs while ensuring optimized

designs, all of the components of the system need to

be completely open source, including the possibility

for printable PV [72] and a fully open source laptop.

5. Conclusions

This study designed and demonstrated the technical

viability of two open-source mobile solar photovoltaic

digital manufacturing facilities. The first, designed for

community use such as in schools, is semi-mobile and

capable of nearly continuous 3-D printing using RepRap

technology while also powering multiple computers.

The second design, which can be completely packed in

a standard suitcase, is intended for specialist travel

from community to community in the developing world

to provide the ability to custom manufacture open

source appropriate technology as needed, anywhere.

These designs not only bring the ability to complete

complex manufacturing and replacement part fabri-

cation, to isolated rural communities lacking access to

the electric grid, but they also offer the opportunity to

leap frog the entire conventional manufacturing supply

chain while radically reducing the environmental impact

of production.

6. Acknowledgements

The authors would like to acknowledge helpful discus-

sions with E. Gilloz, the designer of the FoldaRap, and

technical assistance and support from J. Murduck, H.

McLaren Jr., and A. Stebbins, Tech for Trade and National

Science and Engineering Research Council.

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