PV Gap

Jamie Said:

12V DC brushless fan - I want to run it directly off a PV solar panel - but what size panel?

We Answered:

Due to inefficiencies, you would most likely prefer to slightly oversize the solar panel. That provides more operating headroom during hours when the sun is not peaking, like in the winter and outside 10 am to 2 pm.

Based on the 2 watt rating, somewhere around 5 to 10 watts for the panel rating is reasonable. If the motor is okay with slight over voltage (like 15 V) it should be okay to directly connect it.

However, during evening hours when there is, say, only 0.25 watt available, it would be wise to interrupt the circuit so the motor won't be damaged by low current which is insufficient to turn, though that should not be a problem due to the smarts of most BLDC motors.

The easiest way to protect the motor would be to use a voltage regulator, a simple electronic component (like this http://parts.digikey.com/1/parts/612657-… ) available at electronic component outlets. Choose one rated for at least three times the highest expected current. Most regulators require a filter capacitor, and a choke wouldn't be a bad idea either since stepper motors tend to generate power supply noise.

Danielle Said:

Where can i fing a comperisson between manufactures of solar PV panels world wide?

We Answered:

Hey Ofir, you need to subscribe to Home Power Magazine. It's the only periodical that gets into the nuts and bolts of what you are asking about. About 3 or 4 issues ago they did a comparison of all known commercially available solar panels on the market today. The list compares about 20 items, such as power output, warranty period, size, weight, degradation due to temperature and lifetime, and so on. Each issue they take something related to renewable energy, like inverters, wind turbines, charge controllers, and so on, and compare all the models available.

We started subscribing about 12 years ago, and it's where I still get lots of my information today. Our home is now powered entirely by the wind and sun, so in our case it's been good research over the years. I don't know anyplace else to get the in depth information you are asking for, but I will list some other non profit sources below you can look for on the net, but you'd be better off to just go to Home Power and pay the annual fee, it isn't expensive, then you can research back issues at their website and read any articles in the past, including the one on solar panels. Good luck, and take care...Rudydoo

Jimmie Said:

What conductive wire is the best to get the most out of a PV solar panel?

We Answered:

huh? copper is the most conductive wire in common use.

The wire type is not the issue, all wires are made of copper. What matters is thickness, size of the wire, length, and the proper insulation.

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Holly Said:

How 'green' is the production of silicon for PV solar panels?

We Answered:

There is a bit of a spiel on this link about the manufacture of silicon semiconductors and how they work.

http://www.phys.unsw.edu.au/COURSES/FIRS…

To try and simplify this a bit.

Silicon is one of the most commonly occurring substances on earth. For pv cells it is refined to be virtually 100% pure. (Plenty of heat). Dopents are added to create either a surplus of electrons or a shortage of electrons. Making the final ingot produced either n type or p type respectively.

Slices of p and n type ingots are placed together and electrical connections are made to each side. (Diodes and transistors are made the same way with much smaller surface areas.) In the presence of light an electrical current flows from one contact to the other = electricity.

There are basically two types of silicon cells multicrystaline and monocrystaline. The later is more efficient and require more power to produce because they are manufactured from single crystals.

Not all solar panels are made from silicon. Gallium Arsenide cells are even more efficient and expensive

http://www.mdatechnology.net/techsearch.…

There is a company called dyesol that claims to have produced a solar cell that utilises Artificial Photosynthesis.

http://www.dyesol.com/index.php?page=How…

Most countries have sand that can be refined into high purity silicon. If it is lower silica sand it takes more energy. The white sands usually contain the highest levels of silicon and are usually the preferred source. Countries with large sandy coastlines are the best sources of this sand.

As with anything if there is a buck in it, someone is going to get ripped off. If performed responsibly sand mining can have minimal environmental impact. It disturbs quite a small area which can be revegitated as the activity moves on. When driven by a quick buck it can be a disaster.

In short pv producition can be done in quite a green but not always.
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Peter Said:

Solar Panel PV Surveyors Courses?

We Answered:

British Gas and other firms have been recruiting via totaljobs.com for people to train as installers.

Caroline Said:

solar panel PV system what affect them?

We Answered:

10. Rocks (thrown)

Diane Gonsorowski said:

Digi-Key has recently updated the structure of our URLs and have noticed that you are currently linking to an old URL. The URL is located on the following pages { http://www.pvgap.org/photovoltaics/solar-pv-panel.html]. Could you please update the link on your page from the following: [http://parts.digikey.com/1/parts/612657-ic-regulator-12v-1a-to220fp-ba12t.html] to read [http://search.digikey.com/scripts/DkSearch/dksus.dll?WT.z_header=search_go&lang=en&site=us&keywords=BA12T-ND&x=0&y=0] If you have any questions or concerns, please feel free to contact me. We appreciate your assistance. Best regards, Diane