|
RAINBOW
POWER COMPANY
Email Newsletter # 68
INDEX: 1. WELCOME BACK
2. WEBSITE UPGRADE
3. COMPOSTING TOILETS
4. PEOPLE FIRST NETWORK & PRINTERS
5. 240V FRIDGES
6. CONCLUSION
1. WELCOME BACK: Well Christmas is over and we are all back at it for
an exciting year ahead. I look forward over the next year to bring you
some interesting news and information about Renewable Energy and some
new products as they become available.
2. WEBSITE UPGRADE: We’ve added several dozen new
pages to our website
in the last month. Almost all major products have specifications and
a
picture or sketch on our website. Our Hydro Site Assessment Form, as
well as our Power System Sizing and Solar Pumping Forms are available.
The Plasmatronic Regulator Manuals can be downloaded in PDF format. Our
hydro and the Glockemann pump manuals still need to be added as well
as
pics of our smaller items.
3. COMPOSTING TOILETS: We have added a new range of
composting toilets
to our website. There is a range of styles available to suit the
weekend cottage through to a large family home. Help protect our
environment today.
4. PEOPLE FIRST NETWORK & PRINTERS: Over the last
couple of years we
have been pleased to supply several solar systems to power up remote
email transmitters in the rural areas of the Solomon Islands. It is
great to see solar technology used for such worthwhile projects. David
Leeming who developed and helped set up these rates has written the
following report and request for advice about printers:
“People First Network www.peoplefirst.net.sb is
a rural development and
peace-building project in the Solomon Islands. We aim to provide an
affordable, sustainable and community-owned rural communications system
for the 85% of islanders who live in remote island communities, almost
entirely without telecommunications, and then to help them use the
Internet-based network to access and share information - and to
participate in the emerging "information Society".
With the extreme cost of satellite access in the Pacific
(we are talking
100s of USD per month for a 64kbps connection based on a large number
of
access points - and 1000s for single installations) and the
logistical/security problems associated with relay stations (for VHF
and
microwave / 802.11) - we have opted initially for an HF email network.
Each community email station has a single laptop, a
short-wave radio and
HF modem and printer. The stations have committees to manage them and
operators to help people send emails and others services (Internet
searching via specialized web for mail search tools). They are powered
by a single 80W panel. Initially very few people can operate a computer,
but as the demand grows we add extra computers and offer basic training
and public access to their own emails, etc.
The revenues collected pay for all operations; after
set up there are no
bills sent to the stations, no per minute charges. The main expense is
printer ink. We have been using low-cost Canon bubblejet printers (i.e.
S100SP, S200, etc). However, each new order we make, we find the ink
cartridge is different, and the latest batch had a very small black ink
cartridge. We have tried refill kits but this is proving unreliable when
done in situ and the logistics of sending physical items or doing
maintenance out at the stations are extreme - you need a week in man
cases and the cost in domestic air travel, long open sea canoe
crossings, etc, make this
sustainability issue quite serious for us.
The other issue is power supply. We are forced to use
an inverter for
the printer, whereas all other equipment can be powered from the DC
solar supply. Inverters are fragile and easily abused, unless you pay
a
lot of money. We would like to have a printer with a DC supply - or at
least an internal power supply with a single CD feed which we can "hard
wire" to a DC-DC adaptor specially made locally. However, the Canons
use
three separate voltages from 3V to 22V and this is awkward to arrange.
SO - THIS IS OUR NEED
1. Can anyone recommend the most efficient printer in
terms of cost per
printed sheet. Laser printers are OK if they are low cost and have low
power consumption (they do not need to be turned on all day - only when
needed). The 400Wh we usually get from the 80W panels is usually
sufficient. If we have to pay AUD 50 or AUD 100 for a cartridge, then
an
output of less than 1000 pages at 5% is simply not enough. We should
pay more in order to spend less, I suspect.
2. Ideally, one as in the above, which can be hard wired
for DC
Thanks to Dave Lambert, our resourceful and very helpful
friend and
supplier at Rainbow Power for this networking!”
5. 240V FRIDGES: With the summer upon us and with some
additional
information to hand I have updated this article about using conventional
240V AC fridges on solar systems.
As you know we still recommend 12/24V fridges for solar
systems as being
considerably more efficient than the 240V ones. Despite their higher
cost, we still think it is a cheaper option for residents outside of
Queensland. The situation in Queensland might be more ‘line ball’ in
that most qualify for a 50% subsidy on their renewable energy equipment.
We have come across problems with two 240V fridge installations
(which
we did not recommend). Both have to do with the auto start function on
some inverters. One customer had a fridge that tripped an internal
switch when the inverter went into standby mode. This is apparently a
‘brown out’ protection device for the grid. Another one of our
customers has a fridge that won’t start up when the inverter is
in
standby mode (with nothing else connected). It would seem that this
fridge has some sort of soft start relay that the inverter does not see
as a load. So this customer now needs to keep their inverter on run
mode all the time, which further adds to the inefficiency of the system.
Peter McCloy encountered a problem with a customer who
bought a fridge
with automatic defrost. It would not restart after the defrost cycle,
despite the fact that the light still went on, and if you left it off
for a while it would start again.
These refrigerators use a small heater to defrost but
after the defrost
cycle do nothing for a while, except for a timer which controls the
cycle. This timer does not pull enough current to start the inverter
and so the cycle never finishes. However, if you open and close the
door enough, each time the door is opened the light trips the inverter
and the cycle will eventually finish. Similarly, if you leave it
switched off the temperature rises and the machine will start when you
turn it back on.
Remedy: have someone disconnect the auto defrost cycle,
or leave the
inverter on, but preferably don’t buy an auto-defrost model. However,
we have also had customers who experienced problems with this ’remedy’
as the fridge than iced up excessively (more than an ordinary non
auto-defrost fridge). This type of modification may void the
manufacturer’s warranty.
While I appreciate that some 240V fridges are getting
more efficient, we
suggest you still think twice before going down this track.
Neil McIntosh pointed out that all chest type fridges
use less power
than an upright. In the Queensland summer his 160-litre Fischer &
Paykel 240V chest freezer (run as a fridge) used 768Wh. The same unit
uses 389Wh on 12/24 volts.
I’d also suggest that if you are using a unit designed
as a freezer you
might, in some cases, need to change the thermostat. Consult your
refrigeration mechanic about this.
A few years ago we tested a 220 litre Kelvinator first
on 240V (1.85Wh)
and then modified it to 12V (0.7kWh). Val Rigoli from Fridge and Solar
tested a 140 litre LG model GR-131SSF on 240V (1.36kWh) with a 140 litre
12V Waeco model APR-140RF which used 0.58kWh on 12 volts.
So, to summarise:
FRIDGE SIZE: 12V. kWh / 240V kWh / Difference
140 litre upright: 0.58 / 1.36 / 234%
160 litre chest: 0.39 / 0.77 / 197%
220 litre upright: 0.70 / 1.85 / 264%
These tests were carried out using an inverter with
only the fridge on.
This introduces another ‘variable’ in any test. Some inverters
are more
efficient than others and their efficiency may be better if other loads
in the house are on at the same time.
However, in general terms we can say that an average
240V fridge will
use around double the power of a 12/24V Danfoss compressor type fridge.
This will mean that you would need extra solar panels, batteries and
inverter capacity. While a government rebate may subsidise these costs,
it should be noted that batteries are an ongoing expense and several
hundred extra amp hours of batteries aren’t cheap!
To conclude, we suggest that while the 12/24V fridge
might cost an extra
AUD$1000-$1200, they are still good value if you are going to run a
fridge on a solar system!
PS I am aware that there are a few very efficient AC
fridges available –
these are mostly imported models. Conversely, it is also possible to
make even more efficient 12V models if they are manufactured specially
for the purpose. Boyd had a 198 l fridge/53 l freezer + 102 l vegie box
made for him. It uses 2 Danfoss compressors, and has 75 mm insulation
on the fridge and 125 mm for the freezer. Inside temperatures are –20C
for the freezer, 4C for fridge and 9C for vegie box. It is using an
average of 52Ah per day on 12 volts in 20-40C Ambient temperatures.
This superb efficiency comes at a cost – AUD$4730 in fact!
6. CONCLUSION: That’s all for this month folks!
Your comments and
questions are most welcome; however, there is no need to send our
newsletter back to us when you reply! If you would like a price or
product information, please tell us which country you are from if it
is
not evident from your e-mail address. This allows us to assess if local
GST (tax) is applicable or whether 240 Volt 50HZ products will work in
your country etc.
Dave Lambert and the RPC crew |
