PV Gap

Daniel Said:

Trying to understand electricity in a solar application?

We Answered:

A 12 volt battery produces 12 Watt hours per Ampere hour.
So a 100 ampere hour 12 volt battery stores 1200 watt hours.

As the battery approaches end of its life, or if the water level is low, the battery will store less than rated amp-hours.

Most LED will operate 3 in series on a 12 volt battery to get maximum use. But if your units require 6 volts you would put them 2 in series on 12 volt battery, and still get 0.14 amps of 12 volt power.
25 such groupings will draw 25 * 0.14 amps close to 4 amps, which will run 25 hours on a 100 amp hour battery.

You will likely want to run other things too, so I suggest you go for a 100 amp hour battery.

Now to fully charge that, if a solar panel is putting out 2 watt hours a day for each watt of rated capacity, you need to provide 600 watts of rated capacity. (100 amps hours times 12 volts is 1200 watts. But the original task was to provide only about 500 watt hours, so you could get along with about 250 watts of solar panels.

Those numbers are pessimistic, based on never switching off any lights, leaving them all on all the time. But it is also based on my yield in winter, which may be different from yours.
You would confirm what your local winter output would be per watt of rated capacity. (likely between 1.5 and 5 watt-hours per watt of rated capacity.
One would provide excess capacity in the battery to allow you to store extra power if it happens. Excess capacity in panels is expensive.

Earl Said:

Can a grow light sustain a solar panel with extra power?

We Answered:

A basic law of physics is that of the Conservation of Energy. Energy is not created, nor is it lost. However, it may change form.

The grow light converts electrical energy into light, but some energy is wasted as heat. If you direct the light onto a solar panel, some of the energy is converted into electricity, but more energy is again wasted as heat. Because heat is wasted in this system, it cannot be self-sustaining.

Perhaps you have a misconception about solar panels. The electrical energy created by a solar panel is in proportion to the energy put into it in the form of light. A solar panel in direct sunlight puts out a high level of energy; a solar panel under a full moon puts out much less energy. A solar panel in a dark cave puts out no energy at all.

There is no system that is 100% efficient.