Calculating MY PV Power & Load

tcvb

It's been a while since i had to use my Head with Ohms Law but here is a general idea of what i have in mind + my budget.

I am tying to piece together my system starting off with a few Kyocera 135 Watt panels,looking at a couple of Trojans T105'S,gOT A ProStar 15 solar charge controller.
Have a Sunforce 1000 Watt PSW inverter.

What i am looking at doing is possibly power maybe 600 to 800 watts of lighting load at night for 7 to 9 hours.

Like i said it's been a while with Ohms law anybody want to chime in and give me a quick refresher on the equations to figure my bank and panel needs that i may need.

Thank's Alot i am in the learning process and i think this Forum is awesome not to mention the people at the store also.

BB.

Re: Calculating MY PV Power & Load

Working backwards:

• 800 watts * 9 hours = 5,600 Watt*Hours per day.

Using PV Watts for Norfolk Virginia, assume 1kW of solar panels (round number), 0.52 derating (120 VAC output, flooded cell battery bank):

"Station Identification"
"City:","Norfolk"
"State:","Virginia"
"Lat (deg N):", 36.90
"Long (deg W):", 76.20
"Elev (m): ", 9
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 36.9"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 8.0 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.84, 61, 4.88
2, 4.53, 65, 5.20
3, 4.69, 72, 5.76
4, 5.47, 78, 6.24
5, 5.40, 78, 6.24
6, 5.69, 77, 6.16
7, 5.44, 75, 6.00
8, 5.61, 79, 6.32
9, 5.02, 70, 5.60
10, 4.95, 74, 5.92
11, 4.04, 59, 4.72
12, 3.37, 52, 4.16
"Year", 4.84, 839, 67.12

Assume 9 months of the year solar only. And 3 months of the year, with genset backup. Give us 65 kWhrs per month per 1kW of solar panels:

• 65 kWH per month / 30 days = 2.17 kWhrs per day per 1kW of panels
• 5,600 WH / 2,170 kWH per 1kW of panels = 2,585 watts of solar panels

I can go further--but this gets things started (or I misunderstood your requirements).

-Bill

tcvb

Re: Calculating MY PV Power & Load

BB. wrote: »

Working backwards:

• 800 watts * 9 hours = 5,600 Watt*Hours per day.

Using PV Watts for Norfolk Virginia, assume 1kW of solar panels (round number), 0.52 derating (120 VAC output, flooded cell battery bank):



Assume 9 months of the year solar only. And 3 months of the year, with genset backup. Give us 65 kWhrs per month per 1kW of solar panels:

• 65 kWH per month / 30 days = 2.17 kWhrs per day per 1kW of panels
• 5,600 WH / 2,170 kWH per 1kW of panels = 2,585 watts of solar panels

I can go further--but this gets things started (or I misunderstood your requirements).

-Bill

Bill,

Thank's for the response so i will need about 28 100 watt panels?

BB.

Re: Calculating MY PV Power & Load

TVCB,

It really depends on what your needs are... I guessed at your location, and guessed at your power requirements, and guessed that you would have a back up genset to run 3 months of the year (plus the occasional streak of bad weather during the other 9 months).

What I gave as a panel estimate is a goodly amount of power (and costs)--is this what you need/want (we are probably talking about a $25,000-$40,000+ system (SWAG) here by the time you add batteries, charge controllers, inverters, backup genset, etc.).

Normally, I would be asking you about conservation (choosing the most efficient lighting and lowest acceptable levels). And asking if motion detector controlled lighting would be acceptable.

Is this intended for a long term installation (5+ years) or short term. Will there be fuel available / backup genset? Does it need to be self monitoring (i.e, start backup genset, shutdown loads if battery bank charge is low and genset does not start, etc.)...

I am more than happy to help you size the system--but there is only so much I can do before I would tell you to talk with a local professional to hammer out the system details (we try to educate enough that a person can followup the details with a local supplier). I do not sell or design solar RE equipment.

-Bill