Configuration E1 is based totally on solar energy for all electric generation. To provide power when the sun is not shining, battery storage is used.
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Advantages of this E1 configuration include:
- simplicity relative to other "E" configurations
- completely independent of utility power grid
- few if any mechanical parts to wear out or to maintain
- system can be designed to allow expansion later by adding solar modules and
battery cells if electrical loads grow
Some disadvantages of this E1 arrangement are:
- prolonged cloudy conditions that discharge batteries will interrupt electrical
power
- batteries are used which may (depending on type) require manual watering,
terminal cleaning and equalization charges throughout their life
- batteries have a finite cycle life and will need replacement after a certain
number of years
- electrical loads must be minimized for this system to be attractive
Configuration E2 is based primarily on utility power with supplemental onsite solar electric generation. Special AC PV solar modules are used which consist of a PV module plus an integral AC inverter designed for utility intertie. The inverter is specially designed to shutdown during utility power outages to avoid dangerous backfeed into the grid. The solar generated electricity offsets some of that normally provided by the utility. Depending on system size and load fluctuations it is possible to "sell" excess electricity back to the utility.
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above to enlarge
Advantages of this E2 configuration include:
- easy to install, the ultimate in simplicity
- additional AC PV modules can be added as funds allow simply by daisy chaining
them together
- no battery storage required which reduces initial system cost and ongoing
maintenance
- no dc interconnecting components required since output is totally ac
- each module works independent of the others
- no dangerous backfeed into the grid during power outages
Some disadvantages of this E2 arrangement are:
- electricity from PV modules not available as a backup during power outages unless
many additional components are added
- some utilities require that a second kWh meter be installed to monitor onsite
generation and so that it can be purchased back at a different rate
Configuration E3 is similar to E1 except for an AC engine generator set that can be used to recharge the batteries during prolonged periods without sun light or when AC load demand is larger than normal.
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above to enlarge
Advantages of this E3 configuration include:
- completely independent of utility power grid
- prolonged cloudy conditions that discharge batteries will not interrupt
electrical power
- system can be designed to allow expansion later by adding solar modules and
battery cells if electrical loads grow
Some disadvantages of this E3 arrangement are:
- batteries are used which may (depending on type) require manual watering,
terminal cleaning and equalization charges throughout their life
- batteries have a finite cycle life and will need replacement after a certain
number of years
- electrical loads must be minimized for this system to be attractive
- engine generator requires maintenance
Configuration E4 uses a diversity of alternative generation sources to increase the availability of onsite power. The solar PV generated power is supplemented by wind and/or hydroelectric. The feasibility of using these additional resources is highly dependent on site conditions. But, where these other resources are available, they can create a very advantageous mix.
click thumbnail image
above to enlarge
Advantages of this E4 configuration include:
- diversified energy sources decrease likelihood of prolonged loss of all power
generation
- completely independent of utility power grid
- system can be designed to allow expansion later by adding solar modules, wind or
hydro generators and battery cells if electrical loads grow
Some disadvantages of this E4 arrangement are:
- prolonged loss of generation that discharge batteries will interrupt electrical
power
- batteries are used which may (depending on type) require manual watering,
terminal cleaning and equalization charges throughout their life
- batteries have a finite cycle life and will need replacement after a certain
number of years
- the moving parts in wind and/or hydro turbines require a certain amount of
maintenance
- electrical loads must be minimized for this system to be attractive
Configuration E5 is similar to E4 except for the pre-packaged control panel which simplifies installation. The Whisper wind generators made by World Power Technologies include this kind of control panel. This configuration can also use a diversity of alternative generation sources to increase the availability of onsite power. The solar PV generated power is supplemented by wind and/or hydroelectric. The feasibility of using these additional resources is highly dependent on site conditions. But, where these other resources are available, they can create a very advantageous mix.
click thumbnail image
above to enlarge
Advantages of this E5 configuration include:
- diversified energy sources decrease likelihood of prolonged loss of all power
generation
- completely independent of utility power grid
- pre-packaged control panel is self-contained and simplifies installation and operation of system
Some disadvantages of this E5 arrangement are:
- control panel must be matched to size of wind generator and has limited options
for expansion short of complete replacement
- prolonged loss of generation that discharge batteries will interrupt electrical
power
- batteries are used which may (depending on type) require manual watering,
terminal cleaning and equalization charges throughout their life
- batteries have a finite cycle life and will need replacement after a certain
number of years
- the moving parts in wind and/or hydro turbines require a certain amount of
maintenance
- electrical loads must be minimized for this system to be attractive
