A solar panel has to be connected a charge controller to regulate current, and a battery to store the electrical power. You will need adapter kit cables to wire the solar panel(s) and charge controller, and tray cables connecting the charge controller to a deep-cycle battery.

On-grid simply means solar power equipment (array or solar panel) is connected to the electrical grid, while off-grid refers to systems that are not connected to the grid and therefore store the generated power for later use. Off-grid systems are not affected by grid blackouts.

Solar panel performance may be hindered for a number of reasons. Most commonly environmental conditions such as indirect sunlight, temperature rise, cloudy sky, and dirt and stain build up on the top glass will cause a reduced power output.

Solar panels can be connected in series or in parallel to meet your electrical circuit size and power demand. Connecting solar panels in series will have the effect of adding up their operating voltage output, while system current output will be the same as that for one panel. While, connecting solar panels in parallel will have a different effect; individual panels operating current output will add up to be the system output current, while system output voltage will be the same as the output voltage of one solar panel. To meet the optimum power output and system rating for your power system, you can use both parallel and series connections.

The best way to gauge how many solar panels you need, is to understand and define the power load needed from this system. Power is measured in Watts, and capacity is commonly measured in Watt-hours (multiplying power output in watts by the required number of hours of operation multiplied by a safety factor of 1.5-2). Therefore, it is wise to size your battery bank first based on the minimum required capacity, and accordingly decide how many panels or how much power input is needed.

When you open the product page, you will see a title like "xxx Watt 12 Volt Monocrystalline Solar Panel". The "12V" here does not refer to the voltage of this solar panel (VOC or VMP), but to the fact that one xxxW solar panel is suitable for 12V system (i.e. a 12V battery).Therefore, these are two completely different values with different meanings.