Designing and installing an appropriate solar electric system for your home or cottage generally requires some examination of your energy usage. Defining that usage allows you to size both your solar electric system and your battery storage needs. Follow the steps below to identify your unique energy requirements, and to define your solar energy system to fill those needs.
| Simple PV Calculator (AC loads only) |
| Step 1: Calculate AC load |
AC Load (lights, appliances etc…) |
Rated Watts x |
Hours per Day |
x Days per Week = |
Weekly Watt/Hours |
Line 100 |
fridge |
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|
0 |
TV |
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|
0 |
Lights |
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|
0 |
Lights |
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|
|
0 |
TV/DVD |
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|
0 |
Microwave |
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|
0 |
Toaster |
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|
0 |
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|
0 |
Line 105 |
Total AC Weekly Watt/Hours |
0 |
Line 106 |
AC Inefficiency Factor: |
1.25 |
Line 107 |
Total Adjusted AC Weekly Load (line 105 * line 106) |
0 |
| Step 2: Calculate PV System Requirements: |
Line 202 |
Total Weekly Load (Line 107) |
0 |
Line 203 |
Less Back-up Contribution from Utility/Generator that is not covered by the PV system |
0% |
Line 204 |
Total Weekly PV Load |
0 |
Line 205 |
Daily PV System Requirements (Divide Line 304 by 7) |
0 |
Line 206 |
DC System Voltage (12 / 24 / 48) |
12 |
Line 207 |
Total Daily Amp/Hour Requirement (line 205 ÷ line 206) |
0 |
| Step 3: Calculate PV Array Size: |
Line 300 |
Total Daily Amp/Hour Requirement (Line 207) |
0 |
Line 301 |
Bright Sunshine Hours (from Table) |
4.25 |
Line 302 |
Array Current Required in Amps (divide Line 300 by Line 301) |
0 |
Line 303 |
Module Current in Amps (from Data Sheets) |
Example: Sharp 130 |
7.5 |
Line 304 |
Number of Modules Required in Parallel (Line 302 divided by Line 303) |
0 |
Line 305 |
DC System Voltage (same as Line 206) |
12 |
Line 306 |
Nominal Module Voltage |
12 |
Line 307 |
Number of Modules in Series |
1 |
Line 309 |
Total Number of PV Modules Needed (line 304 * line 307) |
0 |
Continue to Step 4 if you need to calculate battery bank size for off grid or back-up power needs. |
| Step 4: Calculate Battery Bank Size: |
| (Remember: For back-up power needs only include those loads that will need back-up.) |
Line 400 |
Total Daily Amp/Hour Requirement (Line 207) |
0 |
Line 401 |
Desired number or autonomous days (usually 3.5 for PV) |
3.5 |
Line 402 |
Total Daily Amp/Hour Requirement for given autonomy |
0 |
Line 403 |
Maximum Drawdown (typically 50% for lead acid batteries) |
50% |
Line 404 |
Required Battery Capacity in Amp/Hours |
0 |
Line 405 |
Cold weather De-rating factor (for batteries stored outside in winter) |
0% |
Line 407 |
Single battery capacity in Amp/Hours (20 hr rate) |
310 |
Line 408 |
Number of Batteries in Parallel (line 404 / line 407) |
0 |
Line 409 |
DC System Voltage (Line 206) |
12 |
Line 410 |
Single Rated Battery Voltage (per unit) |
6 |
Line 411 |
Number of Batteries in Series (line 409 / line 410) |
2 |
Line 413 |
Total Number of Batteries (line 408 * line 411) |
0 |
