How
big a system do I need?
How
are PV systems sized?
How much do PV systems cost?
How much could I save/earn with the PV system?
Are PV systems expandable?
What happens if there is a blackout?
How big are the panels? How much space
will a system take up on my roof?
What is the ideal orientation for the panels?
What happens when I have to change my roof?
Can I install a solar electric system myself?
How
big a system do I need?
Most
current solar electric power systems in Canada are off-grid, storing
their energy in batteries to supply essential loads. Here is it critical
that the power system is properly sized to provide an adequate amount
of power throughout the year -- sizing calculations are based on the
expected power usage of the load, ie. weather station, cottage, camp,
lighting system etc. Natural Resources Canada has a good guide for
rough sizing of off-grid loads, read
here.
In
the case of grid-tied systems, the North American electrical grid
is there as a backup and sizing need not be based strictly on the
load of your home or business. A system sizing approach is usually
based on a combination of available roof area with good solar exposure
and project budget.
How
are PV systems sized?
PV
systems are typically rated in terms of kilowatts (kW). Basically,
this number is the addition of the rated power output of all the panels
in the system. A 1 kilowatt system under full sun will produce approximately
1000 watts. Grid tied systems typically fall in the range of 1-3 kW,
however many homes could install larger systems up to 8kW for very
large roofs.
In Southern Ontario a kilowatt of installed PV array will produce
1000-1200 kilowatt hours of electricity. By comparison, a typical
family in Canada is using 9-10,000 kilowatt hours per year. For the
typical family, 1 kW will produce 11% of their power usage.
An efficient household, one with new appliances, and an energy conscious
lifestyle will use 4-7,000 kilowatt hours. For them each kW of PV
will produce 16-28% of their power.
How
much do PV systems cost?
The
following installation cost guidelines include labour,
taxes, all hardware, permits and equipment required to connect your
PV system to the grid for a MicroFIT contract.
1.41 kW system $13,000
- $15,000.00
2.82 kW system $15,000
- $17,000.00
3.76 kW system $25,000 -
$28,000.00
4.23 kW system $28,000
- $30,000.00
5.17
kW system $34,000 -
$37,000.00
8.46 kW system $49,000
- $53,000.00
9.87 kW system $56,000
- $61,000.00
The
cost per watt drops as the system size increases because the same
infrastructure costs (labour, connection equipment, inverter etc)
apply to even the smallest systems. PV systems are generally more
cost effective with larger arrays.
How
much could I save/earn with the PV system?
Under the MicroFIT program you would earn $0.802 per kilowatt-hour
of electricity produced. This amounts to $800 to $850 per kilowatt
peak capacity installed under ideal conditions (<10% shade obstruction,
SSE to SSW orientation and tile of 35-55 degrees from horizontal).
Are
PV systems expandable?
Generally
speaking yes, however this should be planned for and discussed during
the site assessment/consultation process. There are certain sizes
that one can expand within depending on the inverter being used in
the system.
A PV inverter is only rated to convert so many watts and cannot be
expanded beyond it's specifications, 1-3kW inverters are common, as
are 3-5kW, 4-7 etc. Also, today's grid tied inverters do require a
minimum startup voltage, meaning you cannot have a very low amount
of PV power (say 1kW) feeding a large inverter (5kW).
What
happens if there is a blackout?
That
depends on your system. Most grid-tied systems have no batteries included
and will not provide power when the grid is de-energized. This stems
from a universal utility requirement that independant power producers
be unable to send dangerous voltage out onto the grid which could
be a hazard to line workers.
For
those concerned about blackouts, a grid tied system can be designed
to include batteries and transfer switching to isolate the home from
the grid and draw power temporarily from the battery bank. A battery
bank will add about 25% to the cost of the system.
**Update**
With the recent announcement that series grid connections are no longer
permissable, a battery based grid-interactive solar electric system
would not be eligable for a MicroFIT contract.
How
big are the panels? How much space will a system take up on my roof?
In
order to reduce the cost per watt and speed installation time, the
trend in the solar electric manufacturing has seen the power output
of modules rise. Standard PV panels intended for grid-tied applications
is 160-240 watts. These panels are approximately 3' x 5' in size.
Every
kilowatt will require about 65-80 square feet of roof space.
What
is the ideal orientation for the panels?
Photovoltaic
panels are quite sensitive to orientation and site conditions. The
optimum compass orientation (called azimuth) is true South, with SE
to SW being perfectly acceptable -- moving East or West drops power
production considerably.
The
best tilt angle for the panels is approximately equal to the latitude
of your location, about 45 degrees for Southern Ontario. Summer only
applications should be tilted lower (30 degrees) and Winter applications
tilted higher (60 degrees) to shed snow and capture the lower sun.
Panels can be flush mounted to roofs or raised off the roof with racking.
Racking is ideal because it achieves the optimum angle and allows
airflow to cool the panels, increasing efficiency. Racking can also
be variable, allowing a homowner to change the angle of the panels
with the season. Ground, pole mounts are also an option with or without
tracking systems.
Shading
is very important to the PV array, especially today's high voltage
grid tied systems where the panels are strung together one to the
other. Shading any one of the modules can choke the flow of electrons
from the entire array by more than 50%. Shadows greater than the width
of your thumb are of concern.
If you're considering solar thermal and photovoltaic technology, save
your best spot for the PV panels!
What
happens when I have to change my roof?
The
array will have to be removed and reinstalled after the roof is redone.
This would require about 0.5-1 day to remove and 1-2 days to replace
-- no disruption to the home's electricity would be required.
Can
I install a solar electric system myself?
Self
installation of grid-connected solar electric systems is definately
not recommended. Only qualified personnel can connect
a high voltage PV system to the grid.
A small off grid cottage type system operating at low voltage can
be self-installed with appropriate electrical skills, caution and
preparation.
The
following installation cost guidelines include labour, taxes, all hardware,
permits and equipment required to connect your PV system to the grid
under the MicroFIT program.
1.41 kW system $13,000
- $15,000.00
2.82 kW system $15,000
- $17,000.00
3.76 kW system $25,000 - $28,000.00
4.23 kW system $28,000
- $30,000.00
5.17
kW system $34,000 - $37,000.00
8.46 kW system $49,000
- $53,000.00
9.87 kW system $56,000
- $61,000.00
These
estimates are based on flush racking on an asphault roof with 235W monocrystal
modules and central string inverters.
