Page last updated Oct 20, 2021 @ 10:08pm
Configuration E
Configuration E is based primarily on the use of alternative energy sources such as solar photovoltaic (PV) modules, wind generators and hydroelectric generators. These configurations can be economical alternatives to the high cost of extending utility lines to remote areas. Since the purchase cost of these systems is usually higher on a per-watt basis than conventional electricity sources, special attention should be given to the use of energy efficient appliances. Electric space heating, cooking, water heating and refrigeration should be avoided and replaced with propane or other fuel sources. Typical configurations are described below using a number of sub-categories.
- Configuration E1 - Solar PV Module Stand-Alone System
- Configuration E2 - Small AC PV Module with Utility Intertie, no Battery Backup
- Configuration E3 - Solar PV Stand-Alone Hybrid with Engine-Generator Backup
- Configuration E4 - Solar PV Stand-Alone Hybrid with Wind/Hydro Generator
- Configuration E5 - Same as E4 except with pre-packaged control panel
- Configuration E6 - Larger PV Module with Utility Intertie, no Battery Backup
- Configuration E7 - Larger PV Module with Utility Intertie and Battery Backup
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.
click thumbnail image
above to enlargeAdvantages 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.
click thumbnail image
above to enlargeAdvantages 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.
click thumbnail image
above to enlargeAdvantages 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 enlargeAdvantages 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 enlargeAdvantages 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
Configuration E6 is based primarily on utility power with supplemental onsite solar electric generation. It is similar to Configuration E2 except that standard DC PV solar modules are used with a separate AC inverter designed for utility intertie without batteries. The inverter is designed with advanced protective systems 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.
click thumbnail image
above to enlargeAdvantages of this E6 configuration include:
- additional DC PV modules can be added as funds allow as long as they are within the inverter capacity
- no battery storage required which reduces initial system cost and ongoing maintenance
- no dangerous backfeed into the grid during power outages
Some disadvantages of this E6 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 E7 is based primarily on utility power with supplemental onsite solar electric generation. It is similar to Configuration E6 except that battery backup is added for providing AC power during utility outages. Optional engine generator backup and/or supplemental wind or hydroelectric generation can be used. The control and distribution design and installation can be simplified by using an Integrated Power Panel which contains all the utility inter-active inverter(s), ground fault protection, charge control, diversion load control, overcurrent protection and disconnects. The inverter is designed with advanced protective systems that detect utility power outages to avoid dangerous backfeed into the grid. When a power outage occurs, the inverter(s) separate from the grid and continue to power essential loads via a sub-panel. 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.
click thumbnail image
above to enlargeAdvantages of this E7 configuration include:
- additional DC PV modules can be added as funds allow as long as they are within the inverter and power panel capacity
- automatic battery backup for essential AC circuits during power outages
- no dangerous backfeed into the grid during power outages
- pre-packaged control panel is self-contained and simplifies installation and operation of system
Some disadvantages of this E7 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
- 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
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