|Emergency backup systems
|Sizing your photovoltic system is dependent on what you plan to operate using the system.
Power demand for appliances can usually be found on the appliance itself or in the owners manual.
Panels can be purchase with a variety of power ratings ranging from 0.1 Watt - 250 Watt,
with voltages ranging from 0.1 - 24volts.
Current output from PV panels varies with power rating, voltage and available sunlight.
|Modules can be connected together to obtain the power needed to operate what you need.
Using 12 volt, 120 watt panels and:
Installing the panels in series will increase the voltage output:
eg. Ten, 12 volt panels installed in series (negative of panel 1 connected to positive of panel 2,
negative of panel 2 connected to positive of panel 3 etc.) will give you a 120 volts at 10
amps which can directly power several household appliances.
Installing the panels in parallel will increase the current output:
eg. Ten, 12 volt panels installed in parallel (all the negative leads connected together and all the
positive leads connected together) will give you 12 volts at 120 amps. This will decrease
battery charging time.
| Power from PV can be used directly or can be stored for later use by including batteries.
Batteries can also be installed in series or in parallel to obtain a desired output. Storage capacity or amp hour rating is what
determines how long a battery will last when subjected to a load. Appliances have ratings that tell how many amps that it will draw.
eg. If you use an appliance operating a 12 volts that draws 5 amps and you use it for 4
hours, then you will have used:
5 amps x 4 hours = 20 amp hours
Then a 12 volt, sealed lead acid, deep cycle battery with a capacity of 100 amp hours will have used 1/5 of it stored power.
Most batteries in a PV system are designed to only discharge down to 80% of it total capacity to prevent damage. This means that
a 100 amp hr battery will supply 80 amp hrs. Once a battery has discharged, the PV panels will recharge the battery at a rate
determined by the size of the panels within the system.
eg. If you have one, 120 watt panel which supplies 10 amps, then it would take 2 hours of
exposure to sunlight to restore the 20 amp hours used by the appliance.
|One of the best uses for PV systems is for the back up of electrical systems in areas where power outages can occur. PV
power can be use to operate heating equipment such as boilers and furnaces as well as televisions and radios for emergency
information and emergency lighting and refrigeration. Installing a PV system for emergency use will also allow you to use
your system for other uses around the house when emergency power is not needed, saving you money year round.
|Another great thing about installing a PV system is that you can start small and add on with time. Since
modules are easily connected together you can slowly build a system to fit your personal needs. Careful
planning can save you money by purchasing the right equipment you will need for your future system.
|Of course the largest reward of using PV and solar technology is that it pays for itself.
The cost of installing a PV system as well as any other system driven by solar energy can be reclaimed with the
money saved by not supporting your local utility companies.
But the actual payback is knowing that you are part of a renewable, earth friendly way of life and supporting
the future health of our world for others to enjoy.
|Micro hydro can be installed in places where water is available at high head and/or large flow rates, as
an alternative to PV generated electricity, and can provide up to 1600+ Watts of continuous power.
|PV is a valuable source of power when out on the water! It can be used to charge deep cycle marine
batteries for use with 12 Volt appliances such as radios, pumps and navigation systems, or for
emergency starting power if needed. Inverters can be added to gain a 110 volt power supply.
| Unless you are a large entity, and get a total write off, is the money spent on a grid tie inverter, instead of a bank of
batteries and a personal inverter, really worth it? You still buy all your electricity from the power company, paying all
their fees, then you sell the power that you have made to them at a much cheaper rate and no fees. Then they turn around
and sell it back to you. Be sure to read the fine print too, if you don't produce, they don't pay.
Besides, don't you think that you would be better off using the power that you generate for yourself, and reduce your
dependence on the large power companies you are trying to avoid in the first place? Also, if everyone feeds into the grid,
they may have to upgrade the grid at your cost! With the new battery technologies emerging, power gain and storage is
getting better and cheaper while utility rates are getting more and more expensive. Plus you get the tax break on the
equipment you install and opererate.