[Equest-users] EQuest Photvoltaic Module

[Dakota Kelley]

Kathryn,

 

I’ve done a small PV array that was more for classroom demonstration than actual electric generation; it had 10 small 170 W panels and one oversized 10 kW inverter for future expansion.  The simulation showed that it produced a peak of 700 W and 81 kWh/yr (in Dallas), this is about what we expected since the panels were barely enough to reach the inverter’s minimum tracking volts.  

 

Your inputs look reasonable for the most part, but here are a few things I would try:

 

·         Make sure your array configuration is accurate.  The “Inverter Module PV Array” screen shot shows default values for the number of panels wired in series and parallel.  This has a big impact on how the system operates.

·         Double check the inverters’ minimum input and tracking volts.  You have both set to 200 V, but there is a minimum operating voltage and a minimum “efficient” operating voltage.  The performance curves won’t fit if the inverters shut down any time the minimum tracking voltage isn’t met.

·         Double check your Short Circuit Temperature Coefficient.  0.05300 seems large (for example, the BP SX170B is 0.00065)

·         Double check your Short Circuit current.  0.24 amps seems very small and implies the panels have a lot of resistance.  I would expect it to be a little higher than the max power current.

·         Under EM1, try setting the cogeneration track mode to simply “track electric load”.  

 

You can also check the PS-C report to see the array’s sum and peak outputs (should be negative values) for the year.  It will also show you the hours for each part load range.

 

Also, I’m not quite sure if you’re including the utility rate screen shots because you’re trying to sell surplus electricity back to the grid.  If so, you’ll need to set up a separate electric meter of type “electric sale”.  That’s a procedure that is a little long to explain, but it’s well covered in the documentation.  Here are a few comments about what I saw in the screen shots:

 

·         “Custom Elec Rate” is not serving any meters.  You’ll want to choose a meter under “Electric Meters Served” for the rate to be applied.

·         Your blocks all have one rate with a size of “1”, so I assume you just want to apply a uniform rate to all kWh.  In this case,  you don’t have to set up blocks.  You can put in the rate under “Uniform Energy Charge” in the rate’s Energy/Demand tab.  You can leave the Energy Charge Schedule undefined if it’s the same all year.  In the same tab, you can fill out the demand charges by month.

 

Thanks,

 

                                

                         DAKOTA KELLEY                                                              

                                Project Designer

 

                                Office:      214-744-6199

                                Cell:         214-280-3825

                                Fax:         214-744-0770 

                

http://www.teliospc.com <http://www.teliospc.com/>           3535 Travis St. Suite 115 

dakotak at teliospc.com <mailto:dakotak at teliospc.com>              Dallas, TX 75204 

 

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From: Kathryn Kerns [mailto:kathryn.kerns at bceengineers.com] 
Sent: Monday, August 10, 2009 12:52 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] EQuest Photvoltaic Module

 

Has anyone successfully inserted a photovoltaic array into an eQuest energy model? I found an example in the Dictionary, created a photovoltaic module and an inverter and attached it to the EM1 utility meter. However, the model’s total energy consumption did not change with this model addition. Since the model uses a Hawaii weather file, I am thinking that there should be some reduction in energy consumption. I have attached the inputs I used and the warning message I got from the output file. Can anyone figure out what I am doing wrong? Thanks.

 

 

 

Kathryn Kerns

Systems Specialist

BCE Engineers, Inc.

| Ph: 253.922.0446 | Fx: 253.922.0896 | 

 

 

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