DIY power 230v filament bulb off grid
This is way simpler than it might sound to you right now.

You need to figure out the total number of watt hours that you need to supply to the load. Account for inverter efficiency - if none is known, assume 80 or 85 percent. Decide how long you can go without sunlight, and you can come up with an appropriate number of amp-hours capacity needed for your battery. Now decide how long you want it to take to regain full capacity on the battery and you can get an appropriate set of solar panels and a charge controller.

You would also want to consult an insolation table for information as to how much sunlight you can expect in your area per square meter. The table will be broken down into subsets based on conditions - for example, if you have a flat array pointed straight up at the sky versus one mounted on a slope.