SOLAR PANELS

How do solar panels work?

The solar panels convert light from the sun into electricity. The output of the solar panels is direct current (DC) electricity. This is converted to alternating current electricity (AC) by an inverter so that electricity can be supplied to the household. Any excess power produced by the solar panels is fed to the electricity grid.

Does the direction the solar panels face matter?

Ideally the solar panels should face north. As their orientation moves away from north the output of the solar panels will decrease. Solar panels facing south will have very poor output.

There is a big tree in my yard, does this matter?

Any shading on the solar panels will decrease their output. This decrease can be quite substantial and hence it is best to avoid shading as much as possible. This shading may be from trees, chimney stacks or even a neighbours large house.

Why don’t the solar panels produce their rated power output throughout the day?

The output of the solar panels depends on various factors including the season, time of day and weather. The power output of the solar panels will be greater during the middle of the day than in the mornings and afternoon, it will also be greater during summer than winter.

What happens at night?

Solar panels require sunlight to produce electricity, hence during the night solar panels will not produce any electricity. For a grid connect system the household will get power from the electricity grid. For a remote area power supply systems the power will come from the batteries.

Will the system still work when it is cloudy?

Solar panels require sunlight to produce electricity. Under cloud the solar panels will not operate at full capacity. The more cloud there is the lower the output of the solar panels.

Will the system still work when there is a blackout?

For a grid connect system when the inverter detects a blackout it will stop producing power. This is to provide a safe working environment for utility workers during repairs to the electricity grid.

How long will it take to install?

A typical system will require one day for installation. Larger systems may take longer.

What are photovoltaic cells?

Photovoltaic cells were developed at Bell Laboratories in the early 1950s as a spinoff of transistor technology. Very thin layers of pure silicon are impregnated with tiny amounts of other elements. When exposed to sunlight, small amounts of electricity are produced.

How long do PV modules last?

PV modules last a long, long time. How long we honestly don’t yet know, as the oldest terrestrial modules are barely 45 years old and still going strong. In decades-long tests, the fully developed technology of single- and polycrystal modules has shown to degrade at fairly steady rates of 0.25%-0.5% per year. First-generation amorphous modules degraded faster, but there are so many new wrinkles and improvements in amorphous production that we can’t draw any blanket generalizations for this module type.

PV technology is closely related to transistor technology. Based on our experience with transistors, which just fade away after 20 years of constant use, most manufacturers have been confidently predicting 20-year or longer life spans. However, keep in mind that PV modules are seeing only six to eight hours of active use per day, so we may find that life spans of 60-80 years are normal. Cells that were put into the truly nasty environment of space in the late 1960s are still functioning well. The bottom line? We’re going to measure the life expectancy of PV modules in decades - how many, we don’t yet know.

Is solar power generation more wasteful than efficient since it costs so much to produce the materials?

In the early years of the PV industry, there was a nasty rumor circulating that said PV modules would never produce as much power over their lifetimes as it took to manufacture them. During the early years of development, when transistors were a novelty, and handmade PV modules costing as much as $40,000 per watt were being used exclusively for spacecraft, this was true. The truth now is that PV modules pay back their manufacturing energy investment in about 1.5 years’ time (only a fraction of the typical warranty period), depending on module type, installation climate, and other conditions.

What is the maintenance on an installed solar power system?

Because they have no moving parts, they are virtually maintenance free. Basically, you keep them clean. If it rains irregularly or if the birds leave their calling cards, hose the modules down. Do not hose them off when they’re hot, since uneven thermal shock could theoretically break the glass. Wash them in the morning or evening. For PV maintenance, that’s pretty much it.

What is an inverter?

An inverter is an electronic device that converts (transforms) the low-voltage DC power we can store in batteries to conventional 240-volt AC power as needed by lights and appliances. Inverters are available in a wide range of wattage capabilities.

What is a PV module?

This is what you might call a “solar panel” that makes electricity when exposed to direct sunlight. PV is shorthand for photovoltaic. We call these panels PV modules to differentiate them from solar hot-water panels or collectors, which are a completely different technology and are often what folks think of when we say “solar panel.” PV modules do not make hot water.