Theres really a few things you have to consider with solar/wind-
effeciency, as far dc/ac rectification (inverters), wattage produced that actually gets put into battery chemical potential, and dc/dc conversion assuming its necessary with your solar setup. Personally, i'd opt for dc led's for solar power, as you skip rectification (dc battery/solar watttage > ac line voltage), which loses ~%10 of power effeciency. Granted, you still need dc/dc converters to regulate the voltage coming out of the batterys (ranges from 11.5-14.1v depending on state of charge), but dc/dc converters can be very effecient. Though led's have narrow spectrum bands compared to hps/mh, or even better spectrum spread cmh lights. You have to consider the wavelength of your leds, since some won't do anything since the plants can't use that particular wavelength of light for photosynthesis.
Prices on solar panels, and battery banks are also a big factor. Pre-built panels are very expensive, if you DIY and make your own frames, wire up solar cells yourself, you can save a TON of money, but you have to really pay attention to protecting it from enviromental factors, mainly moisture. Then you need a good amount of lead acid battery's to store the energy, and a decent charger to keep them healthy. PWM chargers work best to prevent sulfation and prolong battery life, as well as charging the battery's fuller than non pulsed chargers.
For example, if you had to power a 400w light 12 hours a day, thats going to require 4.8 kilowatt hours of power to run. Meaning you need to get more than that from your panels on average, or tie into the grid to makeup for the difference. That means, at least 500w+ of solar panels, possibly even a bit more since the sun doesn't shine all the time, seasonal changes in the amount/intensity of light means you won't get 500w/h from your panels in the winter, and the sun doesn't shine bright enough 12 hours a day anyway to get the max wattage from your panels. So you need to overshoot a few hundred watts in terms of solar panels to account for effeciency losses in rectification/charging, and the fact that they don't kick out 500w all the time, or consistently day to day depending on the weather and season. Rule of thumb, solar is very expensive. I don't think its practical unless you plan on spending a few thousand on a system, or do it yourself on a smaller scale.
Then theres batteries. You prob want a battery bank that can provide 1.5 times the power you need to run your lights, if theres no solar/wind power charging them. For a 400w growlight on 12 hours a day, lets say 500w taking effeciency losses into account, thats 6 kilowatt hours of battery potential. Or a 500ah 12v battery bank, basically a handful of deep cycle car batterys, or a good number of sealed lead acid UPS batteries of smaller ah capacity. As well as decent charger to charge that bank. All the batterys have to be identical too if you want to charge them using one charger, you can't mix/match sealed/flooded lead acid batteries that of different age or usage wear, some will be overcharged (possibly gassing and exploding), some will be undercharged unless they are all the same.
Wind using an alternator, and a dc filter to charge a battery bank works too, but once again, 400w for 12hrs a day is going to need alot of hardware to get that much power. Much cheaper than solar, but the wind has to blow to get any wattage out of it obviously.
If you really want to pursue this, i would find the most effecient lights/system for your indoor grow enviroment, use a killawatt power meter to see exactly how much power you will need, and you might be surprized at how expensive alternative power is.
Not that its a endeavor not worth pursuing, its a hobby of mine as well, but its expensive. Consider diversification of power generation methods, if you live near running water that slopes downward, diverting the flow through a pipe downhill using gravity to gain pressure, and a turbine/alternator to produce wattage is another option as well.
Perhaps, you should look into a well insulated greenhouse, semi-passive geothermal heat pumps (20ft down, the ground maintains 50-60f year round, run a radiator loop down there, insulated pipe to the surface, a dc pump to circualate water through a radiator in the greenhouse and you can grow outside in very cold climates without spending $ on power to heat it electrically). Then see how many hours of usable light you get naturally, and just turn on your lights as necessary. Arduino's and other smart microcontrollers are a good option to design effecient automated systems like this.
Another cool idea i had, was using geothermal heat pumps like i previously mentioned, and exploiting the peltier thermoelectric effect to generate electricity based on the heat potential between the ground (50-60f) and either really cold outside temps, or hot outside temps. Peltier thermoelectric devices can pump heat using power, or generate power between a thermal potential. If you use a passive parabolic solar hotbox to heat water in the summertime, and pump that (insulated) to a copper waterblock like used in computer watercooling to one side of a peltier device, and the same for your geothermal constant 50-60f system on the other, assuming you can get really hot water or really cold water in the winter, theres a possibility of net energy gain after subtracting the wattage needed to pump the water loops by exploiting this temp difference. When the ambient temperature is near 50-60f its not practical as theres not much thermal potential to exploit, and this is all an untested theory of mine, idk if it would even have a net energy gain after powering the pumps.
If sustainable energy is something that interest you, i would research/learn/teach yourself about physics, power electronics, maximizing effeciency in terms of thermal transfer and loads you need to power. Theres lots of solar forums, electronics forums, and books/ebooks you can find about all this. Start with general electronic theory books, and always tinker/expirement to test what you are learning, start on a small scale first.
If you can convert your house to led lighting (very energy effecient), and power that off a hundred watts of solar panels and a small lead acid bank, or large single cell, you can teach yourself to build far more advanced systems. I started off with a 20w panel, and built a backup battery bank kept on a float charge in the event of power outages. Now i'm working on switching all of my lighting (as far as residential, not growing) to dc leds, and expand my solar setup to be able to power all these without using an inverter, since its more effecient. Once thats done, and i use my killawatt to estimate my power needs for lighting, i'm going to build a panel and design a lead acid bank/charging mechanism to run all the lights off solar. Baby steps in essence.
Arduinos are very neat little devices for projects like these as well, they are cheap and so versatile as to what they can be used to do. Whether it be a solar charger controller, led lighting controller, energy usage monitoring/logging, or whatnot.
I'm devoting a chunk of my time to learning about this, and think its a great think to know about as far as meeting your individual energy needs in the future. Since if peak oil is true, our economy will have to change, otherwise food production, distribution, power generation, heating, etc all are heavily reliant on oil and thus if change does not happen, demand will exceed production and people will starve/freeze to death.
I'm not waiting around for someone else to find a solution to those very real problems, i'll try and take care of myself in that respect. Hydroponic indoor/greenhouse food production is a very smart thing to look into, considering how dependent food production (at least in america) is on hydrocarbon fuel. Sustainable energy production and permaculture/ecology is what you need to learn about to understand how to be self reliant in that regard.
TLDR summary- get some ebooks/books on electronic theory, especially power electronics, research effeciency maximization in terms of insulation of heat, and energy effecient loads you need to power, get an arduino to play around with, and start on a small scale. Once you understand it a bit, and make some mistakes to learn from, it becomes alot easier to scale/build what you want to accomplish.
Just know commerical solar is very expensive, and your best bet is building your own panels if you don't want to spend a fortune. Keep in mind effeciency maximization, don't skimp on chargers/converters, and learn as much as possible about the theory behind all the electronics involved, otherwise its easy to make costly and avoidable mistakes. Like frying chargers or dc/dc converters, which i have a bad habit of doing personally
, but you learn why what you did wrong, so you don't waste money doing the same thing again.
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