SOLAR MODULE CLEANER

1 . A photovoltaic (PV) module cleaning system, comprising:

a robotic cleaning device configured to clean a plurality of PV modules; and

a support system configured to provide a first metered fill amount of liquid to a reservoir onboard the robotic cleaning device,

wherein the first metered fill amount is based on a soiling level of the plurality of PV modules.

2 . The PV module cleaning system of claim 1 , wherein the support system is further configured to:

receive an indication of an amount of liquid remaining in the onboard reservoir, wherein the indication is indicative of the soiling level; and

based on the indication, determine the first metered fill amount of liquid to provide to the onboard reservoir.

3 . The PV module cleaning system of claim 1 , wherein the support system is further configured to:

provide a second metered fill amount of liquid to the onboard reservoir, wherein the first fill amount of liquid is different than the second fill amount of liquid.

4 . The PV module cleaning system of claim 1 , wherein the first metered fill amount of liquid is less than a capacity of the onboard reservoir.

5 . The PV module cleaning system of claim 1 , wherein the robotic cleaning device is further configured to apply a substantially constant amount of liquid per unit area to the plurality of PV modules.

6 . The PV module cleaning system of claim 5 , wherein to apply the substantially constant amount of liquid per unit area, the robotic cleaning device is configured to adjust a speed of travel along the plurality of PV modules.

7 . The PV module cleaning system of claim 1 , wherein the robotic cleaning device is further configured to provide an indication of which modules of the plurality of PV modules have been cleaned.

8 . The PV module cleaning system of claim 1 , wherein the robotic cleaning device is further configured to:

travel in a first direction along a first row of the plurality of PV modules until reaching an end of the first row;

apply a cleaning head of the robotic cleaning device to modules of the first row while traveling in a second direction opposite the first direction; and

receive the first metered fill amount of liquid from the support system.

9 . The PV module cleaning system of claim 8 , further comprising another robotic cleaning device, wherein the other robotic cleaning is configured to:

travel in the first direction along a second row of the plurality of PV modules, wherein the second row is adjacent to the first row; and

apply a cleaning head of the other robotic cleaning device to modules of the second row while traveling in the second direction.

10 . A method for cleaning photovoltaic (PV) modules, the method comprising:

a first robotic cleaning device traveling in a first direction along a first row of PV modules;

the first robotic cleaning device changing direction to travel in a second direction opposite the first direction; and

the first robotic cleaning device applying a first cleaning head to modules of the first row of PV modules while traveling in the second direction.

11 . The method of claim 10 , further comprising:

a second robotic cleaning device traveling in the second direction along a first row of adjacent PV modules;

the second robotic cleaning device changing directions to travel in the first direction; and

the second robotic cleaning device applying a second cleaning head to modules of the first row of adjacent PV modules while traveling in the first direction.

12 . The method of claim 10 , further comprising:

a second robotic cleaning device traveling in the first direction along a second row of PV modules, wherein the second row is adjacent to the first row;

the second robotic cleaning device traveling in the second direction along the second row;

the second robotic cleaning device applying a second cleaning head to modules of the second row; and

the first robotic cleaning device cleaning a third row of PV modules that is adjacent to the second row.

13 . The method of claim 10 , further comprising:

after cleaning the first row of PV modules, the first robotic cleaning device receiving liquid from a support system; and

the first robotic cleaning device cleaning a second row of PV modules.

14 . The method of claim 10 , further comprising:

the first robotic cleaning device providing an indication to the support system of a remaining amount of liquid in a reservoir onboard the first robotic cleaning device; and

the first robotic cleaning device receiving a fill amount of liquid from the support system, wherein the fill amount is based on the remaining amount.

15 . The method of claim 10 , wherein changing direction is based on a sensor of the first robotic cleaning device sensing an end of the first row of PV modules.

16 . A robotic cleaning device, comprising:

a curved cleaning head having a middle portion curved toward a front side of the robotic cleaning device relative to edge portions of the curved cleaning head; and

an actuator configured to apply the curved cleaning head to a photovoltaic (PV) module with substantially uniform pressure across a length of the curved cleaning head.

17 . The PV module cleaning apparatus of claim 16 , further comprising at least one squeegee disposed in a rear portion of the curved cleaning head.

18 . The PV module cleaning apparatus of claim 17 , further comprising a brush disposed in a front portion of the curved cleaning head wherein the actuator is configured to apply the brush and the at least one squeegee with substantially uniform pressure.

19 . The PV module cleaning apparatus of claim 16 , wherein the actuator is configured to apply the curved cleaning head at edges of the cleaning head.

20 . The PV module cleaning apparatus of claim 16 , wherein the actuator is a parallel-linkage mechanism.