Quality First Home Improvement Newsletter
There are many choices to make when considering a new solar system. In this article we will discuss various system designs. We will cover photovoltaic (PV) panels, solar water heating systems, pool heating, passive and active systems. ground mounting, and roof mounting options.
IPhotovoltaic (PV) panels
How does solar power work on a home or business? Simply explained, the sun's energy is gathered by the solar panels. The captured energy is converted into DC voltage, the same type of current found in batteries. Cables transfer the DC power energy to the inverter (a box shaped unit that is attached to the building) The inverter changes electricity from DC to AC. AC is the same voltage found in utility power lines. The AC power is ran through your electric box, into your meter, into the house and onto the grid.
If you are using less power in the structure than the PV solar panels are creating, the excess power is fed into the grid, and spins your meter backwards. You are credited by the utility company who monitors your system through a contractual agreement called "Net Metering". Example of a typical solar setup.
Inverters change direct current (DC) electricity that is generated from a photovoltaic panel into an alternating current (AC) that can be used by in-home appliances and the community electricity grid.
Because all photovoltaic panels produce electricity in DC, an inverter is required for all solar power systems to make the electricity usable. There are gird inverters for systems tied to the grid, off-grid inverters, and sine-wave inverters. For our purposes, we will only discuss grid tied inverters. The light gray box in the picture below is a grid-tied inverter.
Advances in inverters have made them more efficient. A good inverter can convert DC into AC with 90-95 percent efficiency.
Enphase Micro Inverters
When using a standard inverter box, solar panels are stringed together in rows called arrays. Even one small shadow landing on one of the panels in the array, will cause a power reduction in the entire array.
If you have some problems with shadows that can't be eliminated, you may consider installing your system using Enphase Micro Inverters underneath each individual panel instead of the standard large inverter box.
Enphase Micro Inverters are wired in parallel, and since each panel has its own associated micro inverter, if a shadow falls on a panel, the other panels are not affected. They are more efficient than standard inverters in low light conditions. Also, each individual Enphase Micro inverter is a router and the entire system can be viewed and monitored on your home or laptop computer, providing all sorts of useful information.
Now let's look at some typical designs. The most common way is to install the panels on a rooftop. Here is a photo of a typical installation
This is how it is commonly done, but in some cases there may not be adequate useable roof space, or the building may be located in an area where there are to many shadows, such as a home in the woods.
Sometimes aesthetics may play a role, as there are those who do not like how solar panels look on a home. In these cases the option would be to install a ground mounted system, provided there is a good location. Also, most often the panels can be positioned in the optimum direction toward the sun, something that can't always be done on a roof which has a permanent fixed direction.
Pick a location that is shade free, where the panels can be optimally positioned. Locating them close to the structure is best, as this will shorten the length of the trench that will used to run the power lines. The picture below shows a very common method of ground mounting panels to a frame structure.
There many ways to ground mount panels, such as pole mounting, as seen below.
or mounting them to a tracker system that uses a small motor to re-position the panels, tracking the sun as it moves across the sky. Be aware that tracking systems have moving parts, and repairs are not uncommon.
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Author - Roland G. Ludlow