"Silicon cells, from which solar panels are constructed, manufactured from 1 ton of silica sand can produce as much electricity as 500,000 tons of coal." |
Solar panels (Solar Direk photo.) |
There's so much information available about photovoltaic systems, it's hard for someone considering installing a system to know where to begin. My purpose in writing on this topic is to highlight some of the information which may interest homeowners in Jamaica.
The usual components of a photovoltaic system are the solar
panels, charge controller, batteries and inverter.
Batteries
I’m starting with batteries, because it's not widely known that, if you are still connected to the grid, and have permission from JPS for that connection, you don’t have to have batteries.
Those used in most PV systems are lead-acid, deep cycle batteries. The
advantage of batteries is that they give you an uninterrupted power supply,
which would be important if you have frequent power-cuts.
The disadvantage of
batteries are
·
that they
are expensive (about Ja$40,000.00 each);
·
energy is lost in charging and discharging them,
making the system less efficient;
·
there are more components to install;
·
as they near full charge, hydrogen is produced
and vented out of the system. Hydrogen is a highly explosive gas, so they
should be in a well-ventilated area, free from naked lights;
·
they require regular maintenance and have to be
refilled with ionized water;
Charge Controllers
The charge controller controls the current going to the
batteries from the panels. It works as a voltage regulator and prevents the
batteries from being overcharged or over discharged, which would shorten the
life of the batteries.
Grid tie system
You can have a grid tie system with or without battery
back-up. Even with battery back-up, there are advantages to this system. It is
not necessary to install a PV system to supply the maximum load – the shortfall
can be supplied from the grid. For example, you may use your a/c units only in
the summer months, at which time the fridges are working harder and fans may
also be in use. Thus your maximum load is in the summer. For the rest of the
year, the load is less. To supply the maximum load without grid tie would mean
more solar panels, and higher cost.
If you plan to install a grid tie system, you should first get permission from JPS. If you have an analogue meter, when you connect your
PV system to the grid, during the day when the panels are generating excess
current, your meter will spin backwards and in the night it will reverse as it
draws current from the grid. If you connect to a digital meter, it will spin
forwards all the time, even when you are sending current to the grid, so you
would be charged for the electricity you have supplied to JPS! So that isn’t
an option. Either way, JPS would prefer that customers apply for Net Billing,
before system is installed.
To apply for Net Billing
1.
Complete the application form in duplicate and
submit one to JPS and the other to OUR (with non-refundable fee of Ja$2,000.00).
Keep a photocopy for yourself.)
2.
Submit the following documents:
a.
Electrical drawings of Renewable Energy System.
b.
A completed System Component Information Form.
c.
Test and compliance certificate for inverters.
(These 3 would have
to be prepared by the company installing your system.)
3.
The Government Electrical Inspector (GEI) has to
inspect the system and approve the drawings, and his certification should be
forwarded to JPS.
4.
Pay at JPS parish office for
a.
Net Billing Meter (about Ja$50,000.00).
b.
Utility Disconnection Switch (if that isn’t
already in your system).
c.
Deposit Upgrade - total of last 3 months light
bills.
5.
Submit proof of insurance, ownership of property
and system.
Solar Panels
A variety of solar panels is available with a range of
prices.
Monocrystalline panels are more efficient than polycrystalline,
because they continue to work at lower light intensities.
The wattage of on the panels indicates the maximum which
they can supply in ideal conditions, i.e. at solar noon on a clear day at a
temperature of 25 degrees C.
One would think that with all the sun we get in Jamaica, our
systems would supply more current than those in a temperate climate. However,
panels are dark in colour and are directly in the sun, so they get hot. Any
increase in their temperature above 25 degrees C reduces their efficiency.
Surrounding air above that temperature would not be able to cool them in the
way a cooler temperature could.
Shading of the panels, including partial shading and cloud
cover, reduces their performance. For example, in July, an array of 12
monocrystalline 300W panels produced a high of 21.3 KWH on a sunny day, and a low
of 4.6 KWH on an overcast day, and an average of 16 KWH per day. As the system
had battery back-up, not all of this was available for use.
Inverters
Solar panels generate and batteries store DC (direct
current), but household appliances use AC (alternating current). Inverters
convert DC to AC. Today’s inverters are sophisticated, computerized pieces of equipment.
There are different kinds for stand-alone systems, for grid tie, for grid tie
with battery backup, and some can even incorporate generators.
Which company?
Listed in the Jamaican Yellow Pages are about twenty
companies which sell and install PV systems. Your choice of company would be
influenced by their experience, expertise, and quality of relationships with
customers. Having selected a company, you can partner with them in
coming up with a design to suit your requirements. They would make a site visit
to see where you propose to locate the panels and inverter, and batteries and
charge controller, if you plan to have a battery back-up system; and recommend
which brand of components you should buy.
Other considerations
With the cost of electricity as it is in Jamaica, most
people have taken steps to conserve, replacing incandescent bulbs with
fluorescent and now LED bulbs, and replacing electric with solar water heaters.
The appliances which use the most electricity, and have the highest wattage, are
those which heat and cool. If you have an electric stove, and have good reason
for not wanting a gas stove, this will present a challenge.
A final word
Find out as much as you can about SV systems before you install, because whatever you buy becomes your responsibility.
The initial cost of the components is high, and they do
require energy for their manufacture. It takes a solar panel about a year to
recoup the energy used in its manufacture. All components of solar systems have
to be imported into Jamaica, and require foreign exchange. However, in the long
run, a large number of PV systems installed would reduce the country’s oil bill.
120,000 customers,
each with 10 x 300 watt panels could provide 360 megawatts, the same amount of
power as the new power plant to be built. Initial cost would be about US$ 1800 million, considerably
more than the new power plant, and less reliable, but eventually could reduce
the oil bill considerably.
Thanks to Solar Direk (in Montego Bay 979-7994 and Kingston 946-9860) for use of their photographs.
3 comments:
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Thanks for giving me the useful information.
solar Shop
You're welcome.
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