Solar Array Calculator

Now that you've seen in our solar panel array guide where the calculations come from, we've distilled all of that, and more, into our convenient solar panel array calculator. To find out more about each parameter and calculated value, hover over each name to see more details.

Use this calculator with actual solar panel values and prices to find out what panel options provide the best total system value for your needs. The lowest-price individual solar panel may not provide the lowest overall system cost.

Continuous Power Design Goal Continuous Power Design Goal
The desired 24-hour continuous power expected from the solar panel array and battery system.
W
Total Daily Required Charging Energy Total Daily Required Charging Energy
The total charging energy which the charger must supply to the battery array each day to meet the continuous power design goal.
Watt-hours (calculated)
Battery Array Voltage Battery Array Voltage
The desired overall voltage of the battery array. Using 24 volts instead of 12 volts will make most chargers twice as effective. See article for details.

Use only similar batteries in each array.
V
Max Battery Array Charging Voltage Max Battery Array Charging Voltage
The maximum battery array charging voltage, calculated as 120% of the battery array voltage.
V (calculated)
Max Charger Input Voltage Max Charger Input Voltage
The charger's maximum allowed input voltage from the solar panel array.
V
Max Charger Current Output Max Charger Current Output
The maximum charger current output at the indicated battery voltage. Determine this value from the charger spec sheet.
A
Max Battery Array Charging Power Max Battery Array Charging Power
The maximum charging power which the charger can supply to the battery array.
W (calculated)
Solar Hours Solar Hours
The number of hours each day the solar array is effectively collecting energy. Five hours is a typical useful estimate.
hours (5 recommended)
Total Daily Available Charging Energy Total Daily Available Charging Energy
The total available charging energy which the charger can supply to the battery array each day.
Watt-hours (calculated)
Maximum Continuous Charger Load Maximum Continuous Charger Load
The maximum continuous load this charger can support, determined by dividing the total daily battery array charging energy by 24 hours. Actual continuous load will also be limited by the available panels, batteries and inverter capacity.
W (calculated)
Consumed Charger Capacity Consumed Charger Capacity
The amount of charger capacity consumed to meet the daily charging energy requirements.
% (calculated)
The charger's ability to supply the desired continuous load will be reported here.
 
Solar Panel Price Solar Panel Price
Individual solar panel price, including sales taxes, if any.

Use only similar panels in each array.
$per panel, incl. tax
Solar Panel Open-Circuit Voltage Solar Panel Open-Circuit Voltage
The rated open-circuit voltage (Voc) of each panel in the array at 1000 W/m2 conditions. See Note #1.

Use only similar panels in each array.
V (Voc, Note #1)
Solar Panel Short-Circuit Current Solar Panel Short-Circuit Current
The rated short-circuit current (Isc) of each panel in the array at 1000 W/m2 conditions. See Note #1.

Use only similar panels in each array.
A (Isc, Note #1)
 
Solar Panel Maximum Power Voltage Solar Panel Maximum Power Voltage
The rated maximum-power voltage (Vmp) of each panel in the array at 1000 W/m2 conditions. See Note #2.

Use only similar panels in each array.
V (Vmp, Note #2)
Maximum Power Voltage Derating Factor Maximum Power Voltage Derating Factor
The de-rating factor applied to the maximum power voltage to obtain the equivalent 800 W/m2 value from the 1000 W/m2 value. See Note #2.

Use only similar batteries in each array.
(typically 0.9, Note #2)
Effective Operating Voltage (NOCT) Effective Operating Voltage
The effective operating voltage of the derated panel. Should match the 800 W/m2 NOCT specification.
V (calculated, Note #2)
Solar Panel Maximum Power Current Solar Panel Maximum Power Current
The rated maximum power current (Imp) of each panel in the array.

Use only similar panels in each array.
A (Imp, Note #2)
Maximum Power Current Derating Factor Maximum Power Current Derating Factor
The de-rating factor applied to the maximum power current to obtain the equivalent 800 W/m2 value from the 1000 W/m2 value. See Note #2.

Use only similar batteries in each array.
(typically 0.8, Note #2)
Effective Operating Current (NOCT) Effective Operating Current
The effective operating current of the derated panel. Should match the 800 W/m2 NOCT specification.
A (calculated, Note #2)
Effective Operating Power (NOCT) Effective Operating Power
The effective operating power of the derated panel. Should match the 800 W/m2 NOCT specification.
W (calculated, Note #2)
 
Minimum Panels Per String Minimum Panels Per String
The minimum number of panels in series in series, totaling the array voltage, not to exceed the input rating of the charger. Calculated by using the fully-charged battery voltage, plus an additional margin. Multiple strings will be used in parallel to form the overall array.

Use only similar panels in each array.
(calculated)
Maximum Panels Per String Maximum Panels Per String
The maximum number of panels in series in series, totaling the array voltage, not to exceed the input rating of the charger. Calculated by using the open-circuit voltage rating. Multiple strings will be used in parallel to form the overall array.

Use only similar panels in each array.
(calculated)
 
Design options are shown here:
Panels Per String Panels Per String
The number of panels per string for this design option. Multiple strings will be used in parallel to form the overall array.

Use only similar panels in each array.
(calculated)
Open-Circuit Array Voltage Open-Circuit Array Voltage
The resulting no-load open-circuit voltage encountered on the array.

Use only similar panels in each array.
V (calculated)
Effective Operating Array Voltage Effective Operating Array Voltage
The resulting effective operating voltage encountered on the array.

Use only similar panels in each array.
V (calculated)
Effective Power Per String Effective Power Per String
The resulting effective power generated by each string in the array.

Use only similar panels in each array.
W (calculated)
Daily Charging Energy Per String Daily Charging Energy Per String
The total daily energy available for charging generated by each string in the array.

Use only similar panels in each array.
Watt-hours (calculated)
Raw Number of Strings Raw Number of Strings
Calculated number of panel strings needed to meet the design requirements. This number will be rounded up to calculate the total number of panels in the array.

If this number is just over a whole number, such as "3.100", then consider slightly reducing the continuous load requirement to remove a full string of panels.
(calculated, see hover note)
Total Number of Panels Total Number of Panels
The total number of solar panels in the array needed to meet the design requirements.
(calculated)
Total Solar Panel Cost Total Solar Panel Cost
The total cost of all solar panels in the array.
$ (calculated)
Total Array Watt-Hours Total Array Watt-Hours
The total actual available watt-hours in the array. This will be greater than or equal to the target watt hours.
Watt-hours (calculated)
Peak Capacity Versus Charger Peak Capacity Versus Charger
The peak amount of charger capacity which can be supplied by this array.
% (calculated)
   
Note #1: The solar panel specs are derived from the manufacturer's data sheet. Open-circuit voltage and short-circuit current are to be entered exactly as found in the datasheet. These should be the 1000 W/m2 rating.

Note #2: The solar panel specs are derived from the manufacturer's data sheet. Maximum power voltage and current must be derated to obtain the nominal operating cell temperature (NOCT) conditions, typically given as a 800 W/m2 rating. If the derated NOCT voltage and current data is given, provide these values in the maximum power voltage and current fields and then set the respective derating factors to 1. Otherwise, enter the non-derated voltage and current, then apply a suitable derating factor (typically 0.9 and 0.8, respectively) to obtain the NOCT power specification.

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