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[Divinorum]

A very simple article about how solar panels work:

http://m.livescience.com/41995-how-do-solar-panels-work.html


My questions for sts community are:

Can you think of any of the many applications for solar panels? (especially in relation to gardening and applied ecology?)

Do any STS members use photovoltaic technology?

What are some interesting and clever ways to combine solar energy with other forms of energy?

All things solar welcome here!

For instance, my little neighborhood is currently working on installing solar panels to pump the well water uphill into storage tanks.

[New Wisdom]

What if somebody who can't grow outside during winter put out some solar panels and hooked them up to some flourescent lights that are indoors.  That way they can power indoor growing with the sun during winter when the temps are too cold. Hehe. That'd be nice.

[Saros]

I'm currently working on automating the opening/closing of my chicken coop door.. since it requires very little power, it'll be a good candidate for solar power:)

If that project goes well, I might convert my greenhouse to solar. Last year I built a little device that monitors temperature and turn on/off the exhaust fan and opens the shutters above a set temperature. Also turns on the misters nightly for several minutes.  Right now it's powered with a really long extension cord from the house, I'd love to get it 'off the grid' The only problem is that the fan pulls a fair amount of power so I'll need at least a 100w panel.

[Greentoe]

I've been thinking about investing in a solar fan for my greenhouse.

I've also been thinking about solar heating for next winter. I'm planning on doing something like this.
http://m.instructables.com/id/How-to-Build-a-Soda-Can-Heater/
Then also putting some 5 gallon buckets in there that are painted black and filled with water to act as heat sinks.

1 Like Saros likes this.

[Saros]

I've been seriously considering doing the buckets/barrels painted black thing as well...  just need to find an affordable source for a bunch of containers:)

LED lighting would be the way to go if trying to use solar power to power indoor lights. Solar panels aren't terribly efficient (around 18% in general if I remember correctly) so you'll need to cover a large area and maximize the light output from the solar energy your panels collect....

I'd love to power my indoor lights with solar panels.. I'd just need a lot of them ( or a few really large ones) and I have no place to mount them but the roof, and to do that I'd probably have to get it all inspected and what not. If I'm going that far, I'd want to do it for more than just my indoor plants:)

1 Like Divinorum likes this.

[Divinorum]

So far extremely interesting and useful information all around! Thank you!

[New Wisdom]

I would need a ton of solar pannels as well. I have about 650 watts of power going with all my flouros and heat pads/fans.

[happyconcacti]

When you angle fixed solar panels, put them at the same angle as your latitude on earth and face them towards the South. This maximizes the total power over the course of a year.

Also, when sizing an array or solar panel, keep in mind that you need a panel that's about 1.5x the voltage requirement of a system. For example, a 12W 1A (12V) solar panel wont charge a 12V battery. It needs to be around 18W (1A, 18V) to charge effectively.

As far as solar technologies go, active systems (photovoltaic) aren't very efficient, yet. There's quite a bit of loss. Most commercial solar panels operate at 14% to 20% energy conversion efficiency. Some of the high-end prototypes are hitting about 42% efficiency. Technology developments typically grow at exponential rates (i.e. memory) whereas photovoltaic technology has only grown linearly since the early 1970's.

If I were to put a bunch of solar panels on my house, I would NOT go off-grid with the system: Battery energy storage is incredibly inefficient. Super-capacitors, that use fractal based geometry of carbon and saline solutions, could potentially be the winning ticket to making "batteries" economically feasible for solar arrays.

I would grid-tie my array and use the grid as my battery bank. This would require a nice inverter that operates at (USA) 120 V AC +-5%. This approaches being economically feasible with the 30% rebates in the US. Essentially, you sell power to the grid during the day, peak hours, and buy it back at night when you need it. 

In my opinion, passive solar technologies are the way to go. Especially for heating applications, efficiencies of 40% to 60% which are common efficiencies for power generation: nuclear and coal.

There are some cool developments with passive solar using Zeolite materials as thermal batteries. Zeolite has near 100% conversion rates of heat. Essentially, heat is used to "dry out" the Zeolite. Zeolite has a unique ability to allow its molecular bonds to expand when dry, thus storing thermal energy. When humidity is introduced, the Zeolite releases its stored heat. Search for "Zeolite thermodynamic cycles" or "Zeolite passive solar" if you want to read more.




Zeolite thermodynamic cycles can also be run in reverse, for cooling:


Hcc

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[happyconcacti]

If anyone is seriously considering photovoltaics, check out this book. Its one of the leading resources on Photovoltaic design.

"Photovoltaics: Design and Installation Manual" by Solar Engergy International (SEI)

hcc

[Sherman]

I am actually taking an engineering class right now on photovoltaics!

My number one advice: avoid shading at all costs! PV panels work like a chain, in that the weakest one brings everyone down to its level. If one panel is shaded, all are shaded!

This could be a good way to make fluorescent lights run, but keep in mind there is less light in winter overall, the time of year when one needs artificial light, which means you may need more panels to run your lights, depending on what your power draw is. Power output is directly proportional to the intensity of light hitting the panels.

Another option for someone like New Wisdom is batteries. If the lower intensity of the winter light is not as big of an issue as the shortness of the days, then the lights could be used to extend the daylight for the plants. Batteries could store the energy from the PV cells through the day, and then provide the required power for a few hours of light in the evening/morning. This would decrease the number of panels needed.

I have actually thought about what an off the shelf solar water heater might do in the winter. It may be enough to keep the greenhouse warm, and the water could be circulated by a PV powered pump.

This is not solar, but I have heard of people just stacking up compost on the north side of their greenhouses during the winter. The compost provides its own heat, which conducts straight into the greenhouse. I've always wanted to try that one, as it seems so simple. Taking it a step farther, I thought about actually putting the compost in the greenhouse, and containing it, with its own ventilation connected to the outside of the green house. It would be kind of like a large wood stove, but instead of burning wood, it heats by microbe power! Just a thought....

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