Photovoltaic array with two-axis power maximization tracking

• US 4,868,379 A
• Filed: 06/20/1988
• Issued: 09/19/1989
• Est. Priority Date: 06/20/1988
• Status: Expired due to Fees

• Current Assignee: Utility Power Group, Inc.
• Original Assignee: Utility Power Group, Inc.
• Inventors: West, Rick
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Chatman, Eric
• Application Number:
  US07/209,010
• Time in Patent Office: 456 Days
• Field of Search: 250/203 R, 250/203 S, 126/425, 136/246
• US Class Current: 250/203.4
• CPC Class Codes: G01R 21/00 Arrangements for measuring electric power or power factor G01R7/12 takes precedence
• CPC Class Codes: G01S 3/7861 Solar tracking systems

Abstract

A control system for maximizing the power supplied by an array of solar cells senses the current and voltage produced and multiplies these to determine the instantaneous power. The array is tilted slightly in a first direction and the effect on the instantaneous power is noted. If an increase in power was produced, a further movement in the same direction is executed; but if the first movement produced a reduction in power, a movement in the opposite direction is executed. The process continues until no increase in power is obtained in either direction. Thereafter, the same process is carried out with respect to a second axis of the solar array.

Claims

1. A method for orienting an array so that it supplies a maximum amount of power to a load, the array being mounted for pivotal motion about a first axis and a second axis, said method comprising the steps of:

(a) pivoting the array about the first axis to whichever position yields the most power while keeping fixed the position about the second axis;

then,

(b) pivoting the array about the second axis to whichever position yields the most power while keeping fixed the position about the first axis.

2. A method for orienting an array so that it supplies a maximum amount of power to a load, the array being mounted for pivotal motion about an axis, said method comprising the steps of:

(a) determining continuously the instantaneous power being delivered by the array to the load;

(b) pivoting the array in a first sense about the axis for a brief interval of time;

(c) determining whether the instantaneous power increased or decreased during the brief interval of time; and

,

(d) continuing the pivoting of the array in a first sense if the instantaneous power increased, and reversing the sense of the pivoting if the instantaneous power decreased.

3. The method of claim 3 further comprising the subsequent step of repeating steps c) and d) until the second of two successive reversals has occurred.

4. A method for orienting an array to maximize the amount of power supplied by the array to a load, the array being mounted for pivotal motion about a first axis and a second axis, said method comprising the steps of:

(a) determining continuously the instantaneous power being delivered by the array to the load;

(b) pivoting the array in a first sense about the first axis for a brief interval of time, while keeping fixed the position of the array with respect to the second axis;

(c) determining whether the instantaneous power increased or decreased during the brief interval of time;

(d) continuing the pivoting of the array in the next brief interval of time in the first sense if the instantaneous power increased, and reversing the sense of the pivoting in the next brief interval of time if the instantaneous power decreased, while keeping fixed the position of the array with respect to the second axis;

(e) repeating steps (c) and (d) until the second of two successive reversals has occurred;

(f) pivoting the array in a first sense about the second axis for a brief interval of time, while keeping fixed the position of the array with respect to the first axis;

(g) determining whether the instantaneous power increased or decreased during the brief interval of time;

(h) continuing the pivoting of the array in the next brief interval of time in the first sense if the instantaneous power increased, and reversing the sense of pivoting in the next brief interval of time if the instantaneous power decreased, while keeping fixed the position of the array with respect to the first axis; and

,

(i) repeating steps (g) and (h) until the second of two successive reversals has occurred.