PV simulation software?

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HI,? which software can I use for the PV panel energy simulation? Thanks.

Wufi2004's picture
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pvwatts

Conrad

Conrad Brown's picture
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Sim-users,

I have a dormitory with something like 3/4 dorms and the rest support
areas.

My question is:

ASHRAE 90.1-2004 calls for in the building wide approach for lpd to be
1.0 w/sf for dorms.

Now if there are wall switched fixed lights called for on the electrical
lighting plans in the dorm rooms but have only a small w/sf
contribution, can I really do a building wide lpd calc and claim the
savings shown on the plans??

Any suggestions??

Thanks.

Howe, Timothy's picture
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Tim,

Table G3.1, No. 6(d) states: "Lighting system power shall include all
lighting system components shown or provided for on the plans (including
lamps and ballasts and task and furniture-mounted fixtures). Exception:
For multifamily living units, hotel/motel guest rooms, and other spaces
in which lighting systems are connected via receptacles and are not
shown or provided for on building plans, assume identical lighting power
for the proposed and baseline designs in the simulations, but exclude
these loads when calculating the baseline building performance and
proposed building performance." [Emphasis in original.]

The way I would implement this is to assign the same W/ft2 lighting to
all dorm rooms on a different meter in both the baseline and proposed
designs. Then I would subtract the kWh of that meter from the building
performance. You could still show lighting savings if you do the
space-by-space method for both designs (assuming the lighting in your
corridors and common areas is efficient).

Regards,

William Bishop, EIT, LEED(r) AP

Bishop, Bill's picture
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Bill, it sounds like you are applying the exception but I don't think it applies here since the lights in the dorm rooms are controlled on fixed wall-switches, and not connected via receptacles. My understanding is that the proposed design should be modeled with W/sf as shown on the plans (however small it is) and the baseline be modeled with 1.0 W/sf as determined by the Building Area Method. Note that if the Space-by-Space method were used the allowable baseline W/sf for the dormitory living areas is 1.1 W/sf.

If the lighting design has LPD less than baseline and fixtures are hard-wired, then credit should be taken.

Thanks,

Dan Russell, EIT

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If you only need to ballpark the cost of a PV system and its output
(thus payback), PVwatts might work for you.

But if you actually need a tool for designing and specifying a PV system
well enough so that it can be built, you need something like Maui Solar
Software. It has modules for grid-tied PV systems, grid-intertied PV
systems, or stand-alone PV systems, as well as Solar Hot water systems.
You can add the latest and greatest panels, inverters, & batteries, or
collectors & tanks if they aren't already in the software. You can model
the solar resource available at the collectors (times when they are
shaded), simulate the building/ occupant's load schedule, and even have
the hourly calculations simulate the savings if one has complicated
Time-Of-Use Metering. It uses the standard TMY hourly climate data
files.

But even though this is the most accurate renewable energy design
software I know of, I recommend that if you haven't been trained in
solar system design, that you get some training before you attempt to do
so, because there are a lot very costly mistakes you can make in design
and implementation. And if you screw it up, you'll be blowing one of the
client's biggest investments and giving solar a bad name. We had enough
of that from amateurs in the 1970s, so at least have a pro check your
work.
Good luck!
Christina

Christina A. Snyder's picture
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The dorm itself is a "dwelling unit", which is exempt from the entire
Chapter 9 requirements (2004 uses the term "living unit"). So I think
the 1.1 W/sf or 1.0 W/sf does not apply to the dorm room. My opinion is
that the lpd in the baseline dorm room should be the same as in the
proposed building unless the applicant convinces the "rating authority"
that what they are proposing is a "significant verifiable departure from
documented conventional practice", per Appendix G.

Michael Rosenberg

Rosenberg, Michael I's picture
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