For one week following each TAP Webinar, which is hosted by the U.S. Department of Energy Technical Assistance Project (TAP) for state and local officials, you are invited to ask questions of the presenters, enter comments about the topic of the presentation, and share your thoughts with others. You can find copies of presentations from the March 24 Webinar in PDF format and audio files in MP3 format and background materials and reports in the TAP Webinar archive.

Question:
What types of data can I upload to the Open PV Mapping Project?

Answer:
The Open PV Mapping Project will accept almost any type of information so long as it relates to an existing PV installation. There are four required fields:

  • Date installed
  • System size or capacity measured in direct current kilowatts (kW-DC)
  • Location: zip code or street address
  • Cost (before incentives)

In addition, you can store other data including photos, installers names, incentive amounts, etc.

Paul Asked:
Is Open PV optimized for a specific browser—Google Chrome, Firefox, Internet Explorer—or can I use the browser of my choice?

Answer:
The Open PV Project is optimized for Firefox and Internet Explorer (IE7)+ browsers. It should work well in Google Chrome, although we have done very little testing to verify its compatibility. IE6 is not recommended, and we know the Web site has some display issues when viewed using this browser. The Flash applications—the Time Mapper and the PV Market Mapper—should be browser independent as they depend upon the Flash Player, which is a plug-in.

Harold Ball Asks:
Is In My Backyard (IMBY) designed only for residential systems or is it scalable to larger systems for use by small businesses or in small industrial settings?

Christopher Helm Answers:
IMBY is designed for smaller systems.

Terri Smith Asks:
Can I use In My Backyard for large PV installations?

Christopher Helm Answers:
Sure. IMBY simulations should scale up to larger systems just fine, but the economics might be off. Remember that incentives play a huge role in determining the simple payback of a PV system, and some of the incentives programs are hard to capture dynamically. Therefore the values that IMBY present for larger systems may be off, perhaps by large amounts.

Tim Gulden Asks:
In the future, can the 30% federal tax credits be generated from the cost of the system as I enter it into IMBY—either the total cost or cost per watt? The default appears to be that IMBY gets the tax credits from the Database of State Incentives for Renewables and Efficiency (DSIRE). Currently I cannot change the tax credit number from what IMBY gives me. Thanks I want to add that IMBY is an excellent tool and I hope it receives additional support in the future!

Christopher Helm Answers:
IMBY pulls both state and federal tax credits from DSIRE. You should be able to change the value of these tax credits and see the impact they have on the total cost and payback of the system.

Ross Asks:
Can we use IMBY for solar thermal applications?

Christopher Helm Answers:
No, not at this time. We're investigating what it would take to include solar hot water into IMBY as well as geothermal heat pumps.

Robert Meade Asks:
Does PV payback treat hourly rates that are emerging from the introduction of smart meters?

Christopher Helm Answers:
No, not at this time. We're working on more realistic utility rate structures and this will certainly be influenced by some if the smart grid work currently under way.

Elizabeth Ridgely Asks:
Can IMBY calculations be made for places where there are no utility companies?

Christopher Helm Answers:
Good question, the answer should be yes, as long as NREL has solar resources data for that location.

Tamara Asks:
What elevation are wind potential calculations conducted for?

Christopher Helm Answers:
IMBY uses wind-speed data at a hub height of 10 meters above the ground. The simulations are run at sea level and then adjusted for the elevation at a particular location. The energy output from a wind turbine at a particular location is proportional to the air density, which, in turn, is proportional to its elevation above sea level.

Kim Asked:
Where can we find the list of 38 states used in the wind simulation?

Christopher Helm Answers:
I don't have the list of states in front of me for which we have wind-speed data. IMBY will tell you if it cannot perform wind calculations in a particular state, but you have to play around a little before you get this feedback.

Steven Asks:
Your tool is returning a payback period much longer than any other tools that I have used. Can you explain this? Are the other tools "too optimistic"?

Christopher Helm Answers:
It is very difficult to say which estimations are or are not correct because different tools take different factors into consideration. Other tools may reflect more accurate payback values due to the ability to customize the scenario for a given user's location. The first edition of IMBY that is currently available is pretty general and is designed to give homeowners a rough estimate of simple payback. Unfortunately, it has difficulties keeping track of the ebb and flow of financial incentives across the country. We hope that IMBY-2.0 will solve some of these issues.

Allan Harris Asks:
When will API be available for download?

Christopher Helm Answers:
We expect to make it available in June 2010.

Milton Asks:
Do the electric rate estimates factor in the different components of the price, such as base charge, demand charge, etc.? Or is it simply an average cost?

Christopher Helm Answers:
The cost in IMBY calculations represents an average cost, which drops with system size. This calculation will change in the next version of the program to take advantage of other projects that are investigating PV costs.

Jose Asked:
Would you please indicate other software tools for measuring solar production numbers based on direct normal insolation and different technologies?

Answer:
Try the Solar Advisor Model, which is available on the NREL Web site.