Solar power can play an important role in smart cities by powering sensors and devices anywhere they are needed, without the cost and disruption of running power lines. Small solar panels and batteries can provide reliable power for systems that monitor conditions like traffic, temperature, and air quality. These solar-powered smart devices can wirelessly transmit data to help cities efficiently manage resources and infrastructure in real-time, improving traffic flow, targeting road gritting, and more. By deploying sensors wherever useful data can be collected, solar power allows smart cities to maximize information gathering and decision making.

1. Solar & Smart
Is there a place for solar in the “Smart
City”?
Chris Angell C.Eng. MIET
Pudsey Diamond Engineering Ltd

2. Everyone Knows a bit About Solar……
• Your garden lights look great for an hour or two…..in
summer
• That solar-powered floodlight on the garage, is ok but it
could be brighter
• Remember the solar-powered calculator which needed
more light than you needed to see by or it couldn’t add
up?
• Do we have enough sunlight in winter to operate
anything useful?
• Solar powered devices are autonomous aren’t they?
They don’t need maintenance!!!

3. This presentation seeks to address
these issues and show how, with
careful consideration of all the
factors, it is possible to power
modern devices, by solar power
alone
As cities become smarter, solar will
emerge as a very smart choice

4. The Case For Solar
• Small solar panels are inexpensive, and batteries are
easy to charge from them
• Solar panels have a long life (typically 20 to 25 years)
• Apart from occasionally wiping them if they get dirty,
they are zero maintenance energy gatherers
• While in countries like the UK the number of sunshine
hours is often limited, the annual average insolation
(solar radiation that reaches the earth's surface. It is
measured by the amount of solar energy received per
square centimetre per minute) is significant
• As long as enough energy storage is provided to store
energy whenever it is available, solar can be made to
work reliably throughout the year

5. Existing Technologies
• Many simple solar powered systems are designed
(primarily for cost reasons) to operate well in the
summer (when energy is abundant) and not so well in
the winter
• In lighting systems this means operating for a few hours
each day but not all night
• This is dubious for lighting and totally unacceptable for
other applications
• The energy demand from the solar powered device must
be reduced by smart engineering to reduce the solar
panel size and the storage battery size
• Until recently, solar powered lighting systems did not
have energy to spare and were not connected to a data
network

6. Reliability
• In the context of solar energy, reliability really
means energy availability
• If the solar panel is too small, insufficient energy will be
harvested to charge the battery system
• If the battery system is too small there will be
insufficient energy stored to reliably operate the device,
and some solar energy will be wasted
• In either case the result will be an unreliable unit

7. The Harvester/Storage Balance
• As days lengthen and shorten with the seasons, the
amount of solar energy available changes too
• In many cases the demand alters with the seasons
too, and not in a good way!
• If solar energy is being used to provide lighting of any
kind, winter provides the greatest solar challenge –
short days, low angle of sun, long nights, bad weather –
it all conspires against solar harvesting
• Summer offers a bumper harvest but we mustn’t
waste it, so determining the capacity of batteries
and panels is crucial

8. The Annual Averages
• Energy harvested throughout the year must match
the demand
0
2
4
6
8
10
12
14
16
18
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
UK Insolation KWh/m2 and number of night hours
(source: "The Eco Experts")
London SE Eng NW Eng Night Hours

9. Achieving Balance
1. Careful calculation and design can ensure that sufficient
energy is gathered during the summer months (when
energy demand for anything illuminated is at its lowest,
and solar energy availability is at its highest) to cover the
energy shortfall during the winter
2. Factors such as total expected insolation (solar radiation
from the sun), battery capacity, total annual demand
must all be used to design a robust system
• The key here is to think “annually” not just day by day
3. Battery efficiency can be easily overlooked, so an
additional factor to compensate for this must be included
(as a rule of thumb the total energy captured should be
1.33 times the actual requirement, to overcome battery
inefficiency)

10. Coming of Age for Solar
• While solar cells and panels themselves have not
fundamentally changed significantly for several
years (except for their cost which has fallen
dramatically) systems powered by them have:
• Modern electronics allows for the design of very
low power devices
• LEDs have dramatically reduced lighting power
consumption
• Part-night lighting has changed the energy balance
making solar easier to employ

11. Coming of Age for Solar
• Battery storage systems have become more sophisticated
• Though Lead Acid systems still have their place – there is no
cheaper chemistry, they can be easily re-cycled and with care they
can perform well against their more expensive “younger brothers”
such as Li ion
• Even wireless (RF) devices are more efficient today and can be
easily shut down when they are not needed
• In fact for telemetry systems, operating licence free, there is a
requirement that they operate at a 1% duty cycle (for transmission)
meaning that for 99% of the time they are only receiving which
certainly helps to drive energy consumption down
• So although solar panel efficiencies have not increased greatly
in recent years (14% - 16%), progress in other areas has
increased the usefulness of solar as an energy source

12. What is Smart in Smart Cities?
• Smart begins with simple control from a remote location
• Turning street lights on and off
• Possibly dimming of streetlights
• Generally used for managing the reduction of energy usage
• This evolves towards improving maintenance
• Data returned from assets about current health (does the
lamp need replacing?)
• Is the asset dirty (requires cleaning)
• Which needs a two-way communication system
• With “intelligent” devices to manage the communication
and asset’s internal sensors
• …and interfacing with CMS

13. But It’s Not Just About Lighting
• The “Smart” in Smart Cities is about gathering data and
using it to improve the city experience for drivers and
pedestrians
• Real-time adjustment of traffic flow (through the use of
dynamic signs)
• Because of congestion
• Poor air quality
• Road Traffic Incident
• …..
• Road level temperature measurement to target the use
of gritting in the most efficient manner or to provide ice
warnings to drivers

14. Direct Information To Your Phone
• After data analysis, some information could be
made available to phone users through “Smart City
Apps”
• Data will be returned to the city via local Wi-Fi
hotspots, or the use of visible light
communications (Li-Fi – Light Fidelity)
• In-car this can be used to inform the driver of road
closures or congestion or could direct the driver to
nearby available parking (in the near future this
will include the availability of car charging points
for electric cars)

15. Information, Information,
Information
• Smart Cities will be thirsty for data
• To make useful decisions about deployment of
resources
• To allow detailed traffic analysis
• To offer predictions about air pollution build up and
movement
• To provide a view of congestion build up, real time,
offering the possibility of re-directing traffic before a
log-jam occurs
• There will be other uses for data, currently unforeseen
– the more data that is available the more analysis that
can be done

16. Sensors Where They Are Needed
(not just where they can be powered)
• At road level (street temperature for gritting
decisions)
• At human height (air quality sensors)
• At the side of the road
• On traffic islands
• Even out of urban and suburban areas
• But providing power to sensors where they are
needed could be very expensive and inevitably
compromises will be made

17. Sensors Where They Are Needed
• Solar powered devices make this possible:
• No mains wiring
• No closing and digging up the road
• Just enough light and a wireless interface
• Put them wherever they are needed

18. Sensors On a Traffic Island
Solar energy
One
current
example is
a traffic
bollard
Powered by
solar,
illuminated
at night by
LEDs
It also
monitors
road
temperature
…
Temperature
…and
ambient
light level…
And makes
the
information
available
wirelessly
Light level

19. Getting Data to the Office
• A quick thought on how data is brought back
• CMS – a general term for control and management –
itself will depend on:
• Open interface(s) – to ensure that all sorts of data can
be gathered from analysis
• Standards – can be seen from two perspectives
• standards undermine “proprietary” systems where a customer
is “locked in”
• BUT offer a wider support for peripherals and opportunities
for manufacturers to introduce their own USP – the mobile
phone is a prime example of this – standards allow phones to
work everywhere

20. Solar is Smart
• Devices powered from solar energy can be deployed almost
anywhere
• After initial outlay they cost almost nothing to run
• Low power solar powered two-way communication allows
measurement, control and data gathering anywhere
• Now a solar powered lighting system can monitor itself and
alert maintenance crews making their work much more
efficient
• Smart can go beyond dimming street lights:
• Sending out gritting trucks only when they are needed is
economically smart and saves energy
• Dynamically controlling traffic flow reduces congestion, improves
air quality and increases productivity – ultimately saving energy in
a very smart way
• Actively monitoring and controlling ambient light levels instead of
controlling by consumed power

21. So, is there a place for solar in the
“Smart City”?
• Clearly solar powered devices can contribute enormously
to the provision of data into the Smart City realm
• Solar is “Smarter” in the broader sense than other
technologies because it is already an energy efficient
technology
• With the cost of providing mains power to ideal sensor
locations sometimes prohibitively high, solar is often the
only solution
• Solar powered devices can communicate successfully into
the Smart City Network, they can be reliable and they are
inexpensive to run
• The answer must be: “YES THERE IS!”

22. Chris Angell
Pudsey Diamond
Engineering Ltd