HOMER Grid 1.9

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The PV page allows you to enter the cost, performance characteristics, and orientation of an array of photovoltaic (PV) panels and choose the sizes you want HOMER to consider as it searches for the optimal system. The PV component can represent both flat panel and concentrating PV technologies.

The PV page provides access to the following tabs:

•Inverter: If the Electrical Bus is set to AC, you specify inverter parameters here.

•MPPT: If the Electrical Bus is set to DC, you set the parameters of the maximum power point tracker (DC to DC converter) here.

•Advanced Inputs are where you can set certain advanced variables.

•Temperature: You specify whether to consider the effect of ambient temperature on panel efficiency, and if so set the relevant inputs.

To add a solar component, click the PV button under the Components tab in the toolbar. On the PV Set Up page, select an option from the drop-down list and click the Add PV button. On the PV page, you can manage information for the model.

Costs

The Costs table includes the initial Capital cost and Replacement cost per kilowatt of the PV system, as well as annual operation and maintenance (O&M) costs per kilowatt.

When specifying the capital and replacement costs, be sure to account for all costs associated with the PV system, which may include:

•PV panels

•Mounting hardware

•Tracking system

•Wiring

•Installation

You can include the costs of the power electronics in the capital cost, or account for them separately in the MPPT or Inverter tab.

Note: The capital cost is the initial purchase price, the replacement cost is the cost of replacing the PV system at the end of its lifetime, and the O&M cost is the annual cost of operating and maintaining the PV system.

Cost Curve

In the Costs table, enter the PV cost curve, meaning the way the cost varies with size. Typically this requires only a single row because analysts often assume that PV costs vary linearly with size. In the sample above, the capital cost of PV panels is specified at $3,000/kW and the replacement cost is specified at $2,500/kW. The operating and maintenance (O&M) cost is specified as 0.

If the cost of the PV subsystem was not linear with size, you can enter multiple rows of data in the Cost table. For example, if the marginal capital and replacement costs dropped to $2,500/kW and $2,100/kW, respectively, for quantities above 2 kW, fill in the Cost table as follows:

If HOMER then simulates a system with a PV array size of 0.1 kW, it would extrapolate from the 1 kW and 2 kW costs, giving a capital cost of $300. For a PV array size of 2.5 kW, HOMER would interpolate between the 2 kW costs and the 3 kW costs, giving a capital cost of $7,250. For a PV array size of 6 kW, HOMER would extrapolate from the 2 kW and 3 kW costs, giving a capital cost of $16,000.

Note: The capital cost is the initial purchase price, the replacement cost is the cost of replacing the PV panels at the end of their lifetime, and the O&M cost is the annual cost of operating and maintaining the PV array.

Size your own

Enter the nominal capacity of the PV in kW, or enter several quantities for HOMER to consider in the system optimization. Include a zero if you want HOMER to consider systems without this PV. Select the HOMER Optimizer if you want HOMER Grid to optimize the size for you. If you select the advanced check box, then you need to specify a lower bound and an upper bound. With the optimizer turned on, HOMER automatically finds the best capacity for you. In the below screenshots, the image on the left is for Size your own while the image on the right is the HOMER Optimizer with the advanced checkbox selected.

   

See the help article about Optimization for a more detailed explanation of HOMER's optimizer.

PV Inputs

From the main section of the PV page, you can edit the following inputs.

 

Note: To the right of each numerical input is a sensitivity button () that allows you to do a sensitivity analysis on that variable. For more information, see Why Would I Do a Sensitivity Analysis?

Advanced Inputs

Click the Advanced button on the bottom right of the PV page, to access MPPT, Temperature and other advanced inputs.

Inverter

This option is available if the PV component is on the AC bus. Solar Inverters convert the DC electricity produced by the solar panels into AC electricity. Using HOMER Grid, we can calculate the optimal sizing of the solar panel and its inverter. The solar panel’s output is the DC power and the output of the inverter is the AC power rating. The ratio of DC capacity (solar panels) to the inverter’s AC power rating is the DC-to-AC ratio. A 120-kWdc solar array with a 100- kWac inverter has a DC-to-AC ratio of 1.2. The typical value for DC-AC ratio is >1 (usually around 1.2)

 

For sizing the solar inverter, HOMER Grid offers two ways to go about this –

1.Enter a list of DC-to-AC ratios

2.Enter a list of Inverter Capacity (kW)

You can define the Cost table, size (Size your own), and lifetime in a similar manner as other components. You can also specify the efficiency with a single value, or check "Use efficiency table," and enter values for efficiency versus input load percentage. If you do not want to model the inverter, check the "Ignore dedicated converter" box.

MPPT

This option is available if the PV component is on the DC bus. A Maximum Power Point Tracker (or MPPT) is a DC to DC converter that matches the PV to the DC bus voltage, while varying the voltage of the PV array itself to maximize the power output. The inputs for the MPPT are identical to those for the inverter, described above.

Advanced Input

The Advanced Input tab contains options that affect the calculation of the PV power output. The article How HOMER Calculates the Radiation Incident on the PV contains more information on ground reflectance, panel slope, and panel azimuth.

Temperature

The Temperature tab allows you to set or ignore temperature effects. See How HOMER Calculates the PV Array Power Output for detailed information on temperature effects on power, nominal operating cell temperature, and efficiency at standard test conditions.

See also

How HOMER Calculates the PV Array Power Output

How HOMER Calculates the PV Cell Temperature

How HOMER Calculates the Radiation Incident on the PV Array

Standard Test Conditions