# Excel PV Program Anyone have?

Solar Expert Posts: 136 ✭✭✭✭✭
Aloha: Anyone out there make a excel program to show calculations? ie: input voltage or wattage or hours of sun, panel size, inverter effeciency etc. and get calculations filled in. You know, the fun stuff!!!
thanks
Frank

Re: Excel PV Program Anyone have?

The PVWATTS website kind of does 90% of the work... I just use the default 0.77 derating factor for Grid Tied systems and use 0.52 for off grid systems with flooded cell lead acid batteries and 85% efficient inverters...

Just take 0.77 overall * 0.85 inverter * 0.80 flooded cell batt = 0.52

You can also output the PVWATTS program in CVS and it will give you 365 days of hour by hour watts/m^2 so you can setup your own detailed spreadsheet.

A lot of the stuff is basic math (using P=IV, E=IR and variations). Most of the stuff I have posted included formulas for battery sizing, array sizing, load sizing, etc...

And those were derived from the general requirements and rules of thumb we use around here...

Many times, it is not worth going for 0.1% accuracy when, in real life--+/- 10% is close enough. And many of the other decisions are Code Related (fusing, wire sizing, conduit fill, etc.) where you pretty much need the NEC or local building code used by your town/county.

What exactly are you looking to calculate?

-Bill
Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
• Solar Expert Posts: 136 ✭✭✭✭✭
Re: Excel PV Program Anyone have?

"What exactly are you looking to calculate?"

Everything!!!! I am a bit of a techie so I like to know info on all aspects of the system.

Frank
Re: Excel PV Program Anyone have?
Aloha: Anyone out there make a excel program to show calculations? ie: input voltage or wattage or hours of sun, panel size, inverter effeciency etc. and get calculations filled in. You know, the fun stuff!!!
thanks
Frank

Check my September 10th, 2007 attachment, it does all that and more.

Cheers,

• Solar Expert Posts: 136 ✭✭✭✭✭
Re: Excel PV Program Anyone have?

Aloha, Bad Apple. Got it, looks interesting, thanks
Frank
• Solar Expert Posts: 9,583 ✭✭✭✭✭
Re: Excel PV Program Anyone have?

Direct link to that post :
http://forum.solar-electric.com/showpost.php?p=7941&postcount=11
Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
|| Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
|| VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

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