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Home Solar Air Heaters

Hi, I’m Amy at the altE Store.We are often asked what the difference is between monocrystalline and polycrystallinesolar panels, so we thought we’d show you. You can see here I have two solar panels made by the same manufacturer, SolarWorld. This one is monocrystalline, and this one is polycrystalline. A couple of things stand out right away with their appearance. This is due to how solar cells, or the individual squares are made. The monocrystalline panel is a consistentblack or very very dark blue color. It is cut into wafers from a conical silicon ingot that’s grown in a lab.

To make the ingot the silicon rocks are melted at 2,500 degrees Fahrenheit, and thena seed crystal is lowered into the melted slush, and slowly pulled up while rotating.It’s almost like making a hand dipped candle, but instead of melting wax, you are meltingrocks. Because of the round shape, there is a lotof material wasted as they cut it into the required square shape.That’s why they usually have rounded corners, to help minimize the waste.If you look at older solar panels, they actually made them with round cells.Here’s a picture of an old Arco solar panel from at least

30 years ago, it still works, for the record. Polycrystalline cells are made a different way.They load about 1300 pounds of silicon rocks into a 3 foot by 3 foot quartz mold to createa square shape, and then load it into a 2500 degree Fahrenheit furnace. It takes 20 hours to melt, and about 3 daysto cool down. The polycrystalline panel has a blue mottled look,like a piece of particle board, it looks like it is made up of multiple pieces of siliconpressed together. That is actually caused from when the meltedsilicon cools and hardens,

it crystallizes, like frost on a window.When it is sawn into the wafers, there much less wasted material from the square ingot than from the round monocrystalline ingot, and is a less expensive manufacturing process.Due to the higher cost of manufacturing, monocrystalline panels tend to be a little more expensive than polycrystalline panels. Although efficiencies in manufacturing processes are really reducing the cost difference.OK, so monocrystalline panels look different and cost a little bit more than polycrystalline. But the big question is, is it worth worrying about the difference?

To help answer that, let’s talk aboutperformance differences. Monocrystalline solar panels tend to be moreefficient than polycrystalline solar panels. Let’s say on average about 17.5% vs.15.5%module efficiency. So they are 2% more efficient. What does thatreally mean? It means that you can have slightly more power in the same amount of space withmonocrystalline than polycrystalline. Let’s look at the two panels I have again. They are both the same size, about 38quot; x 66quot;. The monocrystalline panel outputs 270 watts, andthe polycrystalline puts out 260 watts. If I were to build a system with 20 monocrystallinepanels, I’d get 5400 watts.

To do a similar system with 260W polycrystalline panels, I’d need to use one more panel for 21 panels to get 5460 watts. That would mean a little bit more space, a little more racking, and if using microinverters or DC Optimizers, more equipment needed. So while the cost ofthe solar panels may be less for polycrystalline, the overall system cost may be the same when you take the extra equipment into account. One performance difference is how they react to temperature. Monocrystalline panels handle the heat slightly better than polycrystalline.

Solar powered air conditioning

(Music playing) (Narrator) Over 50 percent of thegreenhouse gas emissions you produce in your home are generated by heating,air conditioning and hot water. In other words keepingyour home warm in winter, cool insummer with nice hot water on tap is emitting2.5 to 5 tonnes of greenhouse gasemissions each year. It also contributes ahefty amount to your

electricity bill, between50 to 60 percent. CSIRO has invented a new solarair conditioning system for Australian homes.This technology solution will reduce Australia’s emissions,reduce your energy bills and reduce our demandfor electricity and gas. If every home inAustralia installed our solar cooling technologyit would be the equivalent of saving15 mega tonnes of CO2

or taking 3.5 millioncars off the road. CSIRO’s solar air conditioningis an innovative three in one technology that provides hotwater, cooling and heating. It uses only a fraction ofthe electricity of current systems and halvesgreenhouse gas emissions. The process begins with atypical solar hot water system. Water is heated by solar panelsand stored in the hot water tank. This solar hot water canthen be used throughout the

home, reducing the needfor gas or electricity. A portion of the hot water isdiverted into CSIRO’s new solar air conditioning unit, which isdivided into two compartments. The hot water entersa heat exchanger in the first compartmentof the unit. Similar to a car radiator the heatexchanger uses the hot water to heat outside air that hasbeen drawn into the first compartmentthrough the vent.

At the same time outsideair is also being drawn into the second compartmentinto a desiccant wheel. The desiccant wheel is the mostcritical part of the system. It is used to dry out the airbefore it goes into the house. Slowly turning thedesiccant material in the wheel continuouslyabsorbs moisture in the second compartment andthen the absorbent material dries out inthe first compartment.

The desiccant material is dried outusing the hot dry air generated by the heat exchanger. This air is then exhaustedoutside the home. The dry air from the desiccantwheel flows through an indirect evaporative cooler which createsa stream of cool dry air. This cool dry air is then fed into thehome in order to cool down the rooms. In winter the solar heated air canbe used directly to warm the house. CSIRO’s solar coolingsystem is a low emissions

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