South Florida Science Museum

New Solar Train Exhibition
Now Open at Science Museum

The South Florida Science Museum is bringing energy conservation and Florida history to their outdoor, interactive science trail with a solar train display. Named the “Solar Express,” the train comes to us courtesy of HighTechScience.org. Visitors can push buttons to move two model trains around a G-Scale sized town, as well as activate other mobile displays, including a carousel, within the “town.”

The solar panels are hooked up to a charge controller, deep cycle batteries and a power converter that converts 12 volts DC to 110 volts AC. This allows the reserve power stored for days, even during cloudy periods.

“ Florida is the Sunshine State, so it makes sense to design the train system with solar power,” says Boca Raton based HighTechScience.org founder, Rick Newman. “I wanted to design the Solar Express to help aid environmental awareness for children and families. Also, Florida was founded on its railroads so it gives a bit of a local history lesson, too.” The Solar Express layout contains a 1950’s model cattle/freight train and a passenger train. “It harkens back to the established East Coast Railroad days, when train travel was still a large part of daily transportation,” says Newman.

The model town and train set up contains more than 500 pieces including model houses, wind mill, farm and other items. The entire exhibit was donated by Rick Newman/HighTechScience.org and other, alternative energy corporate sponsors.
“ It makes a wonderful addition to our outdoor science trail, which has seen a lot of expansions and renovations recently,” says Museum Exhibits Designer/Director Carlos Santos. Santos assisted in designing of the Solar Express layout, as well as creation of the solar panel supports and Control housings. “The Marshall Foundation recently helped restore our wetland area and we have new butterfly beds planted as well. The Outdoor Science Trail is a true gem, and the Solar Express is a perfect fit for it.”

Electrical components used in the "Solar Express"

		ICP Solar Panels 8Amp, 16.5Volt, 130Watt model #SE-8000 http://icpsolar.com

		Bluesky Charge Controller 12 Volt, 25 Amp, Model #Solar Boost 2000E http://www.blueskyenergyinc.com

		Bluesky Temperature Sensor Battery Temp Compensation, Sensor for Charge Controller http://www.blueskyenergyinc.com

		West Marine Batteries Deep Cycle Gel-Cell Batteries, 12 Volt, 73AH, Group 24 http://westmarine.com

		AIMS Power Inverter 12-120 Volt, 150 Watt Pure Sine Wave Power Inverter http://www.aimscorp.net

We would like to thank the following for their donations,
help & support to make this project a reality.
HighTechScience.ORG

Model Trains, RC Boats, Airplanes, Helicopters, Trucks & More

Here's how a
Solar System Works
A complete solar system consists of a solar panel, a battery and a charge controller. If you need 110V AC, a power inverter is also required.

Solar panels produce direct current (DC) power when a solar panel is connected to a battery, this power is stored in the battery for later use. A charge controller connected between the solar panel and the battery monitors the battery and prevents the solar panel from overcharging the battery while assuring a complete charge.

At right: See animated version of how solar power works.

A solar powered system requires an inverter when the DC power needs to be converted into alternating current (AC) power to operate appliances, electronics, etc.

Solar Panels convert light into electricity at the atomic level. Some materials exhibit a property known as the photoelectric effect that causes them to absorb photons of light and release electrons. When these free electrons are captured, an electric current results that can be used as electricity. In 1839, French scientist Edmund Becquerel discovered that certain materials would give off a spark of electricity when struck with sunlight. This photoelectric effect was used in primitive solar cells made of selenium. In the 1950s, scientists at Bell Labs revisited the technology and, using silicon, produced solar cells that could convert four percent of the energy in sunlight directly to electricity. Within a few years, these photovoltaic (PV) cells were powering spaceships and satellites.

The most important components of a PV cell are two layers of semiconductor material generally composed of silicon crystals. On its own, crystallized silicon is not a very good conductor of electricity, but when impurities are intentionally added—a process called doping—the stage is set for creating an electric current. The bottom layer of the PV cell is usually doped with boron, which bonds with the silicon to facilitate a positive charge (P). The top layer is doped with phosphorus, which bonds with the silicon to facilitate a negative charge (N).

The surface between the resulting “p-type” and “n-type” semiconductors is called the P-N junction (see diagram above). Electron movement at this surface produces an electric field that only allows electrons to flow from the p-type layer to the n-type layer.

When sunlight enters the cell, its energy knocks electrons loose in both layers. Because of the opposite charges of the layers, the electrons want to flow from the n-type layer to the p-type layer, but the electric field at the P-N junction prevents this from happening. The presence of an external circuit, however, provides the necessary path for electrons in the n-type layer to travel to the p-type layer. Extremely thin wires running along the top of the n-type layer provide this external circuit, and the electrons flowing through this circuit provide the cell’s owner with a supply of electricity.

Most PV systems consist of individual square cells averaging about four inches on a side. Alone, each cell generates very little power (less than two watts), so they are often grouped together as modules. Modules can then be grouped into larger panels encased in glass or plastic to provide protection from the weather, and these panels, in turn, are either used as separate units or grouped into even larger arrays.

The three basic types of solar cells made from silicon are
Single-Crystal, Polycrystalline, and Amorphous.
Single-crystal cells are made in long cylinders and sliced into round or hexagonal wafers. While this process is energy-intensive and wasteful of materials, it produces the highest-efficiency cells—as high as 25 percent in some laboratory tests. Because these high-efficiency cells are more expensive, they are sometimes used in combination with concentrators such as mirrors or lenses. Concentrating systems can boost efficiency to almost 30 percent. Single-crystal accounts for 29 percent of the global market for PV.

Polycrystalline cells are made of molten silicon cast into ingots or drawn into sheets, then sliced into squares. While production costs are lower, the efficiency of the cells is lower too—around 15 percent. Because the cells are square, they can be packed more closely together. Polycrystalline cells make up 62 percent of the global PV market.

Amorphous silicon (a-Si) is a radically different approach. Silicon is essentially sprayed onto a glass or metal surface in thin films, making the whole module in one step. This approach is by far the least expensive, but it results in very low efficiencies—only about five percent.