sizing PV system in BeOpt

asked 2019-12-20 13:35:27 -0600

yolotom's avatar

updated 2020-01-07 19:50:49 -0600

I am seeking assistance in sizing a PV system in BeOpt for SFam case study in Bakersfield, CA (PGE service area). I have run BeOpt to optimize all but the PV system, getting Site Energy result of 30 MMBTU/y all electric for the local TMY3 weather file (which is outdated and sans urban heat island effect). NREL recommends using the Site Energy result to size the PV system. When I go to the PVWatt online tool, it asks for the PV panel size, but does not include a calculator for that.

1) What is best and/or easiest way to caclulate the PV panel size from my BeOpt results? Here are my initial calcs, but I am not very confident of them:

Site E, annual: 30 x 10E6 BTU/y X (1 y / 8760 hours) X ( 0.29307 W / BTU) = 1.004 kW/h annual avg.

2) Another related question: Should I size on the annual site E, or on peak summer loads? 2019 Title 24 standards require NZE, but I am mainly interested in avoiding indoor overheating during peak cooling demand periods. So sizing to daily, weekly, or monthly demand may be better re: overheating, grid reliability, and carbon emissions. This might lead to a bit of oversizing intitally but would better handle current and future/life cycle cliamte change (coolng degree days will double or triple by end of century).

Some websites recommend sizing for daily load by adjusting for peak # of sun-hours: In BeOpt, I think I can chart/display daily site E use, but have to look it up in support site.

TIA, Tom Phillips Healthy Building Research Davis, CA

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