It’s obvious that high-intensity discharge lamps are the choice for anyone serious about indoor horticulture. Problem is how do you off-set those high power bills that go along with powering high-intensity-discharge lamps. Enter, off-grid solar. Now that you have decided that getting (or remaining) off-grid, solar electricity is the natural choice that will work best for anyone. It’s generally thought that high-pressure sodium are the best overall light when deciding between high-pressure sodium and metal halide. However, 600 watt bulbs may be the best option for indoor gardeners coupled with a good off-grid solar generator to keep down the electrical bills.
Kyle Kushman writes in an article for High Times that more watts or lumens equals higher yields. But bigger isn’t always better. 1,000 watt lights are not for amateurs. If your grow space is 150 square feet or more, you’ll probably want to utilize 1,000s. But if you’re growing primarily for yourself and would like to save electricity, then consider what 600 watt high intensity lights can do. (Four-hundred-watt lamps are out of the question for any serious cherry tomato bud production.)
Kyle argues that 3 600 watt grow lights bulbs for marijuana will give you more bling and produce a better indoor horticluture crop than 2 1,000 watt bulbs. Either way you are going to need a serious amount of off-grid solar to power your indoor garden.
To start figuring out how much off-grid solar you are going to need, start with adding up the total wattage of all your bulbs and circulation pumps, fans and power ventalation. Go to the product specs and look at the watt rating or amps for all your horticulture equipment. Add up all the demand then decide how long you are going to run the high-intensity discharge lamps each day which gives you an idea how much off-grid solar you need.
Kyle makes a point when he says that using 600 watt high-intetensity bulbs creates forty percent less heat which means that the lights can be 40 percent closer to your marijuana plants without burning them. This alone cuts the difference in efficiency between the 1,000-watt and 600-watt lamps nearly in half. And although it will save you some off-grid solar power demands, the off-set will not be significant in the overall design of your solar equipment. The placement of lights is especially important because maintaining the perfect height in relation to your plants is essential to extracting maximum yield. The highest yields and densest buds come when lights are kept close as possible. During times of peak growth, you should adjust the lamp height every day. Set-it-and-forget-it growers should stick with 1,000-watters.
The next step in desiging your off-grid solar for grow lights is to look at the available average sun hours in your area. California has between 6 (San Diego) and 4 (Northern California) of sun hours. Take your total daily wattage and divide by the number of sun hours which will start to tell you how much off-grid solar you need.
Jumping around a little you should keep in mind that multiple points of light commonly called inversion lighting, will encourage the entire marijuana plant into rapid photosynthesis more efficiently. More direct light comes into contact with all parts of the plant, resulting in faster growth rates and more developed buds. Believe it or not, more high-intensity discharge lamps with lower wattage actually produce higher yields. Say you have come up with 10,000 watts per day of off-grid solar needed. 10,000 watts / 5 sun hours means you will need about 2,760 watts produced by your off-grid solar generator.
Because one of the advantages from growing indoors is that you can substantially increase your harvest by growing 24 hours per day. That mean you will need to properly size your off-grid solar system with a battery bank that will keep the lights on all night.
To properly size your off-grid solar system batteries you first take your 10,000 watts / 48 volts = 208 amp hours. Now decide how many day of atonomy (days without sun) you expect in your area. 3 days off-grid is considered a minimum with 5 days the norm.
Now multiply your amp hours by the number of days without sun (In this case we will use 3) and you get 624 aH. Now we need to double the 624 aH needed because the depth of discharge for your batteries should not drop below 50% unless it is an emergency because it can shorten the life of the off-grid solar battery bank used to power your high-intensity discharge lamps used for personal use marijuana growing.
We are not done yet, but we are getting there. Since hot and cold regional temperatures can greatly affect the power of your off-grid battery system, you need use an ambient temperature multiplyer. In this case we will use 1.4 because our high-intensity discharge lamps and system is in Northern California.
1,747 now represents the total battery capacity amp hours needed for our off-grid solar grow light system. Overkill is okay with fans, filters and general safety precautions, but not when it comes to wasting electricity. 600 watt high-intensity discharge lamps are excellent, efficient lamps; so are 1,000s. Either way you go, off-grid solar can keep your plants growing and substantially increase your indoor marijuana horticulture harvest.
Source High Times