The first step to planning your system is to evaluate rebate options and obtain permits. Deciding the size of your system is the next step. With a grid-tied system, size is less critical, because the grid supplies power when your PV system falls short. Systems as small as a couple hundred watts are practical, but you can also install panels that will produce enough electricity for all your needs.
For powering a something that works on DC, like a gate opener, Elaine is right, and in some cases only ONE bigger cell is sufficient due to battery storage; however if the appliance is 20v AC, then an inverter is needed also. MOST of Elaine's answer is good, but a few corrections are needed: Plywood - use EXTERIOR grade only, and even then it can warp; chipboard or waferboard is preferable as it does NOT warp, BUT is not available most places in 3/8, /2 nominal, (5/32) is usually the thinnest available, and it is heavier than plywood. DO NOT use particle board. Superglue - NO, it dries too fast to be useful, in most cases. Wires - For a single cell OK, but for larger panels the best wire is tabbing wire, (which is flat,) which is available from all commercial solar cell dealers. Be very careful soldering this to the cells, as unless you buy the expensive flexible cells, they are easily damaged; I suggest also getting flux pens with liquid flux. Diode - Necessary, but needs to be large enough to handle voltage and current. Usually 25v and 5-30 amps,, one per panel. Plexiglas - OK, but NOT as long lasting as glass; best glass is the special solar glass which is designed to pass almost all of the proper light frequencies, but IS expensive, and usually needs to be specially ordered since most glass stores do not stock it. Double panes work well with the outer pane glass and the inner plexiglas, (to protect the cell if glass broken,) IF where might get damage, such as 'ground' mounting. AND Frame kits are available for larger panels, but IF you make your own, a good table router is a great advantage. Inverter - IF used for 20v AC appliances you MUST have an inverter capable of handling the load, and the best ones are modified sine, or true sine, wave types, and even the best are less than 50% efficient. Note that they will last longer if NOT used at more than 2/3 capacity.
The key is like a spiral stair case with landings at each floor, but the momentum of having to turn is enough to climb from floor to floor. I guess the energetics use the handrail quite utterly and only, pressing against it like bearings in a wheel. With metals and metalloids a 3' x 3' solar panel would power your house and car and make your energy bill negative, but costs several million dollars since the chain of rare elements is only affordable to obtain by strip-mining top soil of many square miles of fertile land just for a single panel and thus destroys good farmland for hundreds if not thousands of years. Clearly solar panels will not solve any problems ever...unless their yours only.
