SolarUK: Solar Water Heating - Sustainable Guernsey

statementdizzyeyedSemiconductor

Nov 1, 2013 (3 years and 7 months ago)

178 views



Nanometer

technology

and how to fix it to a roof

Solar explained
:

2

Who is SolarUK ?


SOLAR
UK



Consumer division of Magpie Technologies (Research and Development)



Established in
1982
, Magpie Technologies developed pioneering IT/Telecoms projects


Migrated into the Solar Thermal industry in
1998
after completing a project for the provision
of power and water in the developing world


Undertakes research and development for leading European Solar companies


Designer and Manufacturer of the complete Solar Thermal system
s


Supplier and Installer of Domestic
, Pool
and Commercial
Systems for ST & PV


Solar Tracker won the
2001
Euro Solar award


An
accredited
MCS manufacturer
and Installer (LCBP)



Member of the Solar Trade Association
(Chairman: Technical Working Group)



LaZer
2
tested to EN
12975
-
1
and shown to have highest yearly output of any tested collector


PV


the science

Today's most common PV devices use a single junction, or interface, to create an electric field within a
semiconductor such as a PV cell. In a single
-
junction PV cell, only photons whose energy is equal to or
greater than the band gap of the cell material can free an electron for an electric circuit. In other
words, the photovoltaic response of single
-
junction cells is limited to the portion of the sun's spectrum
whose energy is above the band gap of the absorbing material, and lower
-
energy photons are not
used.

One way to get around this limitation is to use two (or more) different cells, with more than one band
gap and more than one junction, to generate a voltage. These are referred to as "
multijunction
" cells
(also called "cascade" or "tandem" cells).
Multijunction

devices can achieve a higher total conversion

efficiency because they can convert more of the energy spectrum of light to electricity.

As shown below, a
multijunction

device is a stack of individual single
-
junction cells in descending order
of band gap (
Eg
). The top cell captures the high
-
energy photons and passes the rest of the photons on
to be absorbed by lower
-
band
-
gap cells.

Solar cells are made of the same kinds of semiconductor
materials, such as silicon, used in the microelectronics
industry. For solar cells, a thin semiconductor wafer is
specially treated to form an electric field, positive on one
side and negative on the other. When light energy strikes
the solar cell, electrons are knocked loose from the atoms
in the semiconductor material. If electrical conductors are
attached to the positive and negative sides, forming an
electrical circuit, the electrons can be captured in the form
of an electric current
--

that is, electricity.

4

Solar Thermal and Photo Voltaic (PV)



93% conversion rate 17% conversion rate

5

The Basics

The sun gives out an almost unlimited amount of energy; when the sun shines
there are about 1000 watts of free energy available for every square meter of land.


The sunlight landing on the earth’s surface in one
hour

is equal to all the energy
used in the world in one
year
!

In the UK, there is five times more energy in the summer month than in the winter


With Solar, you are buying 25 years worth of energy


6

Transfer of Heat


Three Ways:


Conduction

-

Transfer of heat from one material to another


Convection

-

Movement of the material to transfer heat


Radiation

-

Energy emitted from a material (travels in straight lines so kW/m
2

is fixed)


LaZe
r2 Collector
-

893Kwh/m
2
/pa

7

Which type is best ?


Depends on target temperature

8

Vacuum tube and flat plate



9

Commercial System

Design ST


Sizing:


>
50l
per m
2


Normally
75l
per
m
2



<= 100l
per m
2

10

If the objective is to obtain
10
% of the buildings energy
from solar, there is often lack of roof space (after air
handling equipment etc is installed)


The benefits of
Alkorbright

SolarUK has teamed up with
Renolit
, makers of the
Alkorbright

roofing membrane for flat roof waterproofing, for a trial
showing that its solar panels work 9% more efficiently when
installed on this flat roof waterproofing surface.

The durable white colour of the
Alkorbright

membrane
maximises the sun’s reflection, cooling the temperature of the
building and reducing the cost of air conditioning.



The more sunlight that reaches the panels, the more energy
you get.

12


13

Leatherhead Police Federation
-

CPW


Planning requirement for
10
%


Original proposal supplied
8
%


By combining high efficiency panels with low frame angel
allowed the output to be increased to
12.4
% (same cost)


14


The addition space on the roof has proved very
useful, since there have been some last minute
additions to the roof. This sometimes happens.

15


16


17

And if you run out of roof space, there
are always the walls

18

Virtual Cylinders


By splitting the cylinder into multiple
cylinders, each with multiple coils, reduces
costs and increase effectiveness



The solar heats the top of the first cylinder
to
60
c and then moves onto the next
cylinder



Commercial systems are sized to cope with
maximum water usage (i.e. are oversized)




If the solar heats
1000
l of water to
60
c, and
1000
l is all that is used that day, the boiler
will not fire


a perfect solar system

19

PV


Why Grid Connect ?


Roof Fixings

Industrial Installations


G
59

PV rules of thumb


1kw = 8m
2
(May need 16m
2

if anti
-
shading)


1kw = 950Kwh per year


1kw = £5000 installed


1kw = 500Kg C02 savings


1kw = 100Kg roof weight


24

The Future


Solar thermal for Hot Water, absorption chillers
and the electricity


Both
will
be required to meet Government targets


The number of companies involved will go up,


BUT the true knowledge will go down.

SolarUK

www.solar
uk.net

Geoff Fox

01892 52 63 68

Geoff@SolarUK.net