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Solar Electric Consulting - Residential On/Off Grid Design - Structural Building Plans and Drawings

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Utility Grid Tie Interface Systems New Residential Existing Residential Commercial Grid Tie System Components Solar Panel Arrays (in low or high voltage strings) Combiner Box with Circuit Breakers or DC T Fuses Grid Tie Inverter that converts Direct Current(DC) from the Panels into Alternating Current(AC) to send to the Grid or power your home loads. It should include: -Ability to Synchronize to the Grid Voltage and Frequency -Grid Sensing Relay (For disconnecting/reconnecting from the grid during and after a blackout) -Built in AC and DC Surge protection -GFDI(Ground Fault Detection Interrupter) -DC Disconnect and DC Ground(all DC components are now required to be grounded thru the Inverter) -A Power Output Meter +/-5% with display for Systems receiving the Expected Performance Based Buydown Incentive(EPBB Systems) A Performance Meter +/-2% with online Monitoring and Data Recording capability for Systems receiving the 5 year Performance Based Incentive(PBI Systems) The Main Service Panel with Circuit Breakers and AC Ground The Utility Meter that records your net usage if the Performance Meter doesn't Utility Interface System Diagram Design Considerations for Solar Electric Installations on New Residences New Residential Construction with a Solar Electric Grid Tie System must have Energy Efficiency 15% above what is currently required under California's Title 24 Standards for heating, cooling and water heating to be eligible for the $2.50 per watt Rebate from the CEC's New Solar Homes Partnership program. The System must also meet more stringent orientation, tilt and shading restrictions and the solar panels and inverters must be high performance modules approved by the CEC. Go to the NSHP Website for more information. System Size: Roughly kWh per day that you need x 1.2 (inefficiency derate) divided by number of hours of sun per day (about 5.3) Estimated Monthly kWh Usage Number of Approved Panels Required to Offset Usage Size of Inverter needed for Max Watts The minimum and maximum inverter input dc voltage limits Highest and Lowest Site Temperature Limits for Inverter Output Number of Panels in each Series String Number of Parallel Strings High Temperature Voltage Minimum and Low Temperature Voltage Maximum for the Solar Panel Array Go to the NSHP PV Calculator Website to get your adjusted incentive amount for your system. California Flexible Installation Criteria: Is the Roof Orientation between 150 degrees and 270? Optimal Orientation is usually pointed slightly west of due south to accomodate maximum afternoon a/c loads. Is the Roof Pitch between 4/12 and 7/12? The panels must be installed at the same tilt as the roof. A Minimal Seasonal Shading analysis must be made. Roof Load: Structural Requirements for added Load on the Roof Wind Load: Maximum Wind Velocity expected Attachment Requirements - Size, Number and Length of Bolts used for Mounting System Panel Setbacks from Roof Edges Location of System Components: Easy Access for Maintenance Length of Wiring Runs (Voltage Drop Calculations) Location of PV and Utility Disconnects if required Convenient connect to Main Service Panel and Performance Meter Metering Requirements: All Systems must include a performance meter or an inverter with a built in meter so that the customer can determine the amount of energy produced by the system. The meter must be CEC approved, accurate to +/-5%, able to retain data during a power outage and provide a display of system output that the customer can easily understand. A list of eligible performance meters, solar panels and inverters that have built in meters is available at this Go Solar California Website. Wiring and Panel Options include Net Metering which credits the power you create against the utility power you use on a yearly basis. Utility Backup Options: Critical Loads Only (this allows for a smaller Battery Bank but requires a separate Sub-Panel dedicated only to certain Loads) Number of Batteries depends on how long Utility Backup is wanted and the number of Loads to be powered For more information about Grid Tie Systems with Battery Backup go to Utility Backup Design . Design Considerations for Solar Electric Installations on Existing Residences The California Solar Initiative starting Jan 1,2007 made the CPUC, thru your Utility Provider, the administrator for Solar Grid Tie Systems installed on existing residential buildings. See the CSI Website for more information. System Size: Roughly kWh per day that you need x 1.2 (inefficiency derate) divided by number of hours of sun per day (about 5.3). Use the CSI Calculator to determine your estimated incentive when applying for a CSI incentive reservation. Only optimum systems will qualify for the maximum rebate. Current Monthly kWh Average Usage Number of Panels Required to Offset Usage Size of Inverter needed for Max Watts The minimum and maximum inverter input dc voltage limits Highest and Lowest Site Temperature Limits for Inverter Output Number of Panels in each Series String Number of Parallel Strings High Temperature Voltage Minimum and Low Temperature Voltage Maximum for the Solar Panel Array Note - Since the Utility does not as yet pay for power you send to the grid once you have equaled the value of the the power you use, the size of the system should be designed to produce less than your yearly kWh usage. This is especially true for TOU (Time Of Use) plans that charge you less for power at night. For example, if you are generating 5 hours per day at a rate of 21 cents/kWh and using power from the grid at a nightly rate of 8 cents/kWh you would need a much smaller system to equal the cost of your total usage. Orientation and Roof Pitch: Site Inspection Is the Roof Suitable or is a Ground Mount Required? Seasonal Shading Analysis - even partial shade will drastically reduce the output of most panels Panel Mount Orientation for Optimum Panel Output. This depends on the latitude of the site. In warm climates the array is usually pointed slightly west of due south to accomodate maximum afternoon a/c loads. Roof Load: Condition of Shingles and Support System Structural Requirements for added Load Access to Roof Support Members Wind Load: Maximum Wind Velocity expected Attachment Requirements - Size, Number and Length of Bolts Panel Setbacks from Roof Edges Location of System Components: Easy Access for Maintenance Length of Wiring Runs (Voltage Drop Calculations) Location of DC and Utility Disconnects Convenient connect to Utility Service Panel Utility Backup Options: Critical Loads Only (this allows for a smaller Battery Bank but requires a separate Sub-Panel dedicated only to certain Loads) Number of Batteries depends on how long Utility Backup is wanted and the number of Loads to be powered For more information about Grid Tie Systems with Battery Backup go to Utility Backup Design. Metering Options: Utility Rate Options include Net Metering which credits the power you create against the utility power you use on a yearly basis. This meter is provided if the old utility meter is not adequate. The Time of Use (TOU) option will require a meter that records when power is sent to or received from the Grid with 3 different rate schedules - Baseline, Offpeak, Peak. This may be favorable for residential customers who would send power to the grid at peak rates during the day and use grid power at lower nightly rates. However, their system must be smaller because if the net cost of power sent exceeds the net cost of power used the utility will not pay the difference. Also the incentive will be smaller for the smaller system. Currently TOU rates are in flux as well. The Performance Metering and Recording of Power Output for PBI systems requires a new meter (+/-2% accuracy) and 5 years of Data Monitoring (PMRS) by a PMRS Service both at owner's expense. For EPBB systems that get an upfront incentive the Inverter Meter can be used in most cases and the PMRS requirement can be waived if the cost exceeds 1% of the system cost (.5% if over 30kW). Random data sampling might also be an option soon. A list of eligible solar panels, performance meters and inverters that have built in meters is available at this Go Solar California Website. Performance Meter Requirements For Commercial and Existing Residential Systems Incentive Type System Size Minimum Meter Accuracy Performance Communication and Reporting Requirement Cost Cap EPBB < 10 kW +/- 5% Yes 1% EPBB 10 kW to 30 kW +/- 5% Yes 1% EPBB 30 kW and greater +/- 5% Yes .5% PBI < 10 kW +/- 2% Yes No Cost Cap PBI 10 kW to 30 kW +/- 2% Yes No Cost Cap PBI 30 kW and greater +/- 2% Yes No Cost Cap Design Considerations for Solar Electric Installations on Commercial Buildings The California Solar Initiative starting Jan 1,2007 made the CPUC, thru your Utility Provider, the administrator for Solar Grid Tie Systems installed on commercial buildings. See the CSI Website for more information. Commercial Utility Grid Tie Systems are similar to Residential Interface Systems but must meet stricter structural, safety and fire codes that might include: Access to PV DC Disconnects for fire fighters and police, including notification, installation of locks and providing keys. Preventive measures such as fencing to safeguard the general public. 1-2 hour fire sub-sheathing. Handicap access to breakers, disconnects and other components. Schedule 80 PVC Conduits in exposed locations. Re-roofing and Insulation above existing building codes to reduce power usage. Commercial buildings generally have higher California Energy Efficiency requirements than residential structures. System Size: Roughly kWh per day that you need x 1.2 (inefficiency derate) divided by number of hours of sun per day (about 5.3) Use the CSI Calculator to determine your estimated incentive when applying for a CSI incentive reservation. Only optimum systems will qualify for the maximum rebate. Current Monthly kWh Average Usage Number of Panels Required to Offset Usage Size of Inverter needed for Max Watts The minimum and maximum inverter input dc voltage limits Highest and Lowest Site Temperature Limits for Inverter Output Number of Panels in each Series String Number of Parallel Strings High Temperature Voltage Minimum and Low Temperature Voltage Maximum for the Solar Panel Array Note - Since the Utility does not as yet pay for power you send to the grid once you have equaled the value of the the power you use, the size of the system should be designed to produce less than your yearly kWh usage. This is especially true for TOU (Time Of Use) plans that charge you less for power at night. For example, if you are generating 5 hours per day at a rate of 21 cents/kWh and using power from the grid at a nightly rate of 8 cents/kWh you would need a much smaller system to equal the cost of your total usage. Orientation and Roof Pitch: Site Inspection Is the Roof Suitable or is a Ground Mount Required? Seasonal Shading Analysis - even partial shade will drastically reduce the output of most panels Panel Mount Orientation for Optimum Panel Output. This depends on the latitude of the site. In warm climates the array is usually pointed slightly west of due south to accomodate maximum afternoon a/c loads. Roof Load: Condition of Shingles and Support System Structural Requirements for added Load Access to Roof Support Members Wind Load: Maximum Wind Velocity expected Attachment Requirements - Size, Number and Length of Bolts Panel Setbacks from Roof Edges Location of System Components: Easy Access for Maintenance Length of Wiring Runs (Voltage Drop Calculations) Location of DC and Utility Disconnects Convenient connect to Utility Service Panel Metering and Rate Options: Utility Rate Options include Net Metering which credits the power you create against the utility power you use on a yearly basis. This meter is provided if the old utility meter is not adequate. The Time of Use (TOU) option will require a meter that records when power is sent to or received from the Grid with 3 different rate schedules - Baseline, Offpeak, Peak. This may be favorable for residential customers who would send power to the grid at peak rates during the day and use grid power at lower nightly rates. However, their system must be smaller because if the net cost of power sent exceeds the net cost of power used the utility will not pay the difference. Also the incentive will be smaller for the smaller system. Currently TOU rates are in flux as well. The Performance Metering and Recording of Power Output for PBI systems requires a new meter (+/-2% accuracy) and 5 years of Data Monitoring (PMRS) by a PMRS Service both at owner's expense. For EPBB systems that get an upfront incentive the Inverter Meter can be used in most cases and the PMRS requirement can be waived if the cost exceeds 1% of the system cost (.5% if over 30kW). Random data sampling might also be an option soon. A list of eligible performance meters and inverters that have built in meters is available at this Go Solar California Website. Utility Backup Options: Critical Loads Only (this allows for a smaller Battery Bank but requires a separate Sub-Panel dedicated only to certain Loads) Number of Batteries depends on how long Utility Backup is wanted and the number of Loads to be powered For more information about Grid Tie Systems with Battery Backup go to Utility Backup Design . For Information on California's Solar Rebate Program and Federal Tax Credits see the Solar Incentives Page or the California Solar Initiative Web Site. For more information call (707) 462-2427 or E-mail Collins By Design Cal Contractors Lic #B557124 Pictures compliments of Advance Power and Zapsucker.com