Welcome to All Weather Energy's
Questions about Solar Power!!
What is Solar Power?
Solar Power is power made from the sun.
There are a couple of different ways to produce power from the sun.
What we will talk about here is known as Photovoltaics or PV for short.
Photovoltaics stands for (photo=light, voltaics=electricity).
PV is created using silicon-based wafer's which are sandwiched with other
materials used to convert light energy into electrical energy in the form
of Direct Current or (DC). This process uses nothing but the sun, has no
moving parts, no other fuels required to do this and therefore creates no
pollution.
What does PV cost?
PV can cost anywhere from a couple of $Hundred Dollars to $Millions of Dollars,
every thing is relative to what you want to do.
1. First you need to know who you are buying electricity from:
A. Some City's have there own Power Plants and they can provide power very
cheap.
B. If you do not live where power is supplied by a local government agency
it can be very expensive.
C. You need to find out what your costs per kWh, you look at your kWh usage
on your electric bills for a year, calculate a daily average, and divide
that by the number of average daily sun hours for your location.
For example: 3600 kWh/yr divided by 365 days/yr equals approximately
10 kWh/day, divided by 5 sun-hours per day (for locations in middle America)
equals 2 kW. This would indicate that a 2-kW system would, over the course
of an average year, produce enough energy to replace the power you are
currently using.
2. If you just want Backup power when your electricity goes out, it could be just
a couple of Thousand Dollars.
3. If you want Solar for your primary Residential power, it could cost from
$5000.00 to $50,000.
4. If you want PV for a location too far from current utilities this could save
a lot. It could be a lot less expensive than running a power line to a site
currently without service.
5. If you are building a new home and want the maximum energy efficiency this is
probably the way to go.
A. If you design an energy-efficient home, you could cut the annual electricity
usage dramatically, reducing the size of the system. In the real world, the
majority of home systems range from 1 kW to 2 kW. Factors such as your
location, on the grid versus off the grid and lifestyle will dictate the size
of your system and its ultimate cost and value.
B. If you design a new home with total energy efficiency, most appliances would
be DC, which is more efficient because the PV process produces DC current.
Most homes now are wired for AC (alternating Current). To run AC appliances
with a PV system you need an inverter to change DC to AC, which will loose
some power during the inversion process.
Every application is unique and generalizations on cost are difficult to make.
How long will a PV system last?
PV modules will usually last in excess of 20 years.
Other system components will vary, Batteries and Electronics can last 2-15 years.
What makes up a PV system?
A PV system is comprised of the PV modules, Batteries, Inverters,
Support Structure, Wiring, and the Electronics.
Will Solar Energy actually save me money?
It really depends on were you live. Some city's you can't beat there prices
because they have there own Power Company's. It all depends on what you pay
per kWh.
How long has PV been around?
The photovoltaic effect was first recognized by Edmund Bacquerel, in France,
in 1839. Scientists made solar cells of selenium in the 1880s. And modern PV
technologies were developed at Bell Labs and RCA Labs in the mid-1950's.
The best energy saving tips!
1) Change your lighting from "standard" incandescent bulbs to compact fluorescents
(CF) and halogen bulbs. You can get 75 watts worth of light with 20 watts of
electricity using a CF. Changing your lighting can reduce your electrical
demand by 10-20%.
2) Replace aging appliances with either top of the line electric models or switch
to gas models. A typical older refrigerator can use 100kwhours per month.
We have models that use less than 20kwhours. Switching from an electric hot
water heater to a gas or oil tankless system can save more than $400 per year.
Switching to Kerosene heat can save per year from:
Electricity $ 2000.00
Liquid Propane $ 1000.00
No.2 Oil $ 600.00
Natural Gas $ 500.00
Wood Stove $ 300.00
Pellet Stove $ 100.00
These are Approximate Estimates for homes from 1,000 to 2,000 sq.ft.
These estimates are for comparison purposes only.
There are a lot of variables depending on where you live.
You can gradually move towards this goal by replacing one appliance per
year and one light bulb per month, or take a home improvement loan and do it
all at once!
3) You should make your place as Energy efficient as possible before you think
about adding renewable energy sources to the mix. Either PV panels or Wind
generator's are the most efficient or cost efficient at this time. They charge
a bank of batteries that supply electricity to an inverter. The inverter
transforms the direct current (DC) electricity from the battery to 120 AC
(household current). The inverter can interface with the utility company and
sell to them the excess power.
Note: Not all states require the utility companies to buy back the excess power.
In some states they are only required to give you credit for the time's you
may need to use there power.
4) You can start with powering your garage or shop and outdoor lighting and
gradually add panels and/or wind power until energy independence is achieved.
Just think that every dollar you spend on efficiency saves you money in the
long run.
Do PV systems work better in hot or cold weather?
Most PV panels power output is reduced at high temperatures, however
places where it is hot enough to effect the efficiency, usually have
more hours of sunlight in a year to produce electricity.
This by far usually offsets the reduction in efficiency.
Most PV module's have a life of 20 to 30 years. The life of PV modules
are not affected by normal (outdoor) heat.
The duration and intensity of sunlight has a greater effect on the
output of a PV module, then the increase in temperature has a
lesser effect on the output. Therefore, a PV module installed in a
hotter climate will put out much more energy over a year than the
exact same system installed in a colder region.
The design of a PV system should take into consideration the need
to allow some "convective cooling" for the PV modules. The usual
method is to leave the back open and allow air flow around the modules.
What types of materials are used in making a photovoltaic cell?
The most common material used for PV cells is silicon, a semiconductor.
The silicon is "doped" (it has a certain amount of impurities placed into it)
with either boron or phosphorus to give it the properties needed to be a
PV cell and give up electrons when exposed to light. The photons of light
(photons are actually small particles of light) "knock" the electrons out of
the outside band of the silicon atom and that is what creates the PV effect.
Silicon is made from sand and the sand is refined to be very, very pure).
Other materials are selenium, gallium-arsenide, copper and selenium,
and cadmium telluride.
What is the efficiency of current PV cells?
In 1954 a cell was produced that operated at four percent efficiency.
Current PV cells range from about 8 to 18 percent.
Some very special cells have been produced that are in the high 20s.
Most single crystal silicon cells usually average about 14 percent,
thereby giving module efficiencies (sunlight to DC energy)
of 11 to 12 percent. Next year there are supposed to be panels out that
have a cheaper to make and have a much better efficiency rating.
If PV arrays get dirty, will they deliver less power?
Yes, depending on a lot of variables you can have a reduction between
1 and 20 percent. Research is ongoing to determine how and when to clean
your modules properly.
Troubleshooting a PV system.
Somes causes of malfunctions are extreme temperature and climate changes,
lightning and static electricity, moisture and wind, as well as faulty
manufacturing and or installation.
Selective Shading Test,
*Note: If you have Soft panels with bypass doide's between each cell (shade tolerent)
this will not work. You have to shade the whole panel.
If your array is in a parallel or series-parallel configuration, find something that
will shade at least 4 cells. Shading just a few cells should drop the module's output
to less than half. Monitor the current, with the array connected and working,
shade portions of the panels, you should notice current drops. If you get to an area
where there is no current drop then that panel is either defective or if you have
any other panels wired in series they may be or there is a fault in the wiring.
Fading in the Heat
The voltage of a PV module usually decreases with temperature rise.
12 volt PV modules are designed to sustain good current flow all the way to
17 or 18 Volts at 25°C. If heat fade is severe, it can be caused by weak PV
modules, undersized wiring, poor connections, and controller's.
You can confirm heat fading by cooling the array with water while the system
is operating. If your current rise's to normal you need to determine where
the voltage drop is. Connect a voltmeter directly to the PV array
(or its combiner box). Disconnect the array from the controller, in order to
read the open circuit voltage. If it is less than 18 V (for a 12 volt
configuration), then part or all of the PV array may be defective.
The selective shading test can help determine this. Reconnect the array
to the system. Under good sunlight, test for voltage drop in the wiring by
measuring the voltage at the array, and then at the controller input.
Note that voltage drop in wiring will increase in proportion to the current
flow. Next, test for drop in the controller by measuring the voltage at its
PV input, and then at the battery terminals. Remember, if the battery is
fully charged, the controller should drop the voltage. If that is the case,
you can bring down the battery voltage by turning loads on. When the battery
is at less than 13.5 V (for a 12 volt system), the controller should allow
full current to flow. If a voltage drop occurs between 2 points you probably
have a bad connection. Check battery connections, connections between
modules and contoller for corrosion, oxidation or overheating.
These all can cause a drop in total output. When you repair corroded,
oxidized or overheated connections, replace all metal parts that have been
damaged. You can buypass charred terminals on PV modules by soldering a
wire directly to the metal strip that leads to the PV cells.
Diode Failures
Most PV modules have bypass diodes in the junction boxes, to protect the panels
from overheating or a lightning strike. On rare occasions a diode will fail.
It will usually short out and reduce the module's voltage drastically.
To test diode check the resistence (ohms) in both directions. If it is shorted
it will test to near 0 ohms both ways. It should be around .7 one way and
infinite the other.
Always replace bad diodes with a silicon diode with amps rating at or above the
module's maximum current, and with a voltage rating of 400 Volts or more.
Food for Thought!
1) The cost of electricity is only going to increase. Fossil fuel sources are
finite and will only become more scarce as time goes on. Nuclear clean-up,
storage of spent waste and "mothballing" of old plants is going to cost more
than a trillion dollars (that's with a "t", 1000 billion dollars,
and a billion is 1000 million).
2) With Solar, Wind and other Alternative's we will not run out of fuel and
will not pollute for future generations tocleanup. We are not vulnerable
to rising costs or even simple line failures as long as we are with current
electricity sources.