Big Plans for the Spring

I've been wanting to own a big system for quite a while, and I feel I've learned enough to handle it. I may not know the answers, but when I don't, I know where to look and who to ask in order to get them.

I'm considering getting into the wholesale herb market. There are quite a few decent restaurants within 25 miles of here as well as farmer's markets where I could sell directly. I found a 160 site (yes, 160 plants!) system that will fit in an 8'x 8' area.

It uses 3.5" netpots with only enough expanded clay pellets (aka: LECA, Hydroton) to hold the seedling in place until it's roots can grab the netpots. It's an aeroponic system with fine mist sprayers. This type of system is *extremely* high performance, but does require a lot of monitoring - filters must be cleaned daily, nozzles checked to make sure they don't clog, and a back-up pump and UPS is a must. Since there is no media to retain water, a pump failure or power outage can turn the roots to hay and destroy the entire crop in a matter of a couple of hours.

Being aeroponic, it only needs about 2/3 strength nutrient solution which saves a considerable sum of money over the course of a year.

Here's a picture of the system:


Systems available through retail are ridiculously expensive. This one is no exception (though for the number of sites, it's relatively cheap compared to most). It prices out at about $3500. (Yikes!).

I've already begun researching parts and am pretty certain I can build just as well for $400-$500. I'll be making a few modifications such as plumbing a second pump into the same lines with a back flow prevention valve and alternating cycle timers. That way if one pump fails, the other will keep the plants alive and well (though obviously slowing growth somewhat) if a failure should occur while I'm on vacation.

The real issue with this system is the cost of electricity. you want 40-60 watts per square foot of HID lighting. With a high performance system such as this, you definitely want to have 60w/sf. Here's my calculations:
Pd160 is 96" x 84", 58" height.
96"/12"=8 ft
84"/12"=7 ft
8'x 7'=56 sf
60w*56sf=3,360 watts

Biggest lights are 1000 watts.
That's 3x1000 watt lights. That would give us:
3000w/56sf=53.57 watts/sf
We can use a rail-type light mover to make up the difference.

As a side note:
600 watt lights are a lot more efficient wrt lumens/sf (they can be placed closer, and are also much cooler, which means less climate control issues), but 1000 watt lights penetrate deeper. Something I'll need given the "V" configuration of this system and the fact that the basil will be growing 18-24" tall... a 600w won't penetrate that far below the canopy top with sufficient light to keep the lower growth alive.
The whole issue of lighting is rather complicated. I know almost nothing about it and could write a few chapters. Just take my word on it. Unless there is no choice for your application (such as this one), use more 600w's, or even more 400w's before choosing a 1000w light.

Back to the problem at hand:

3x1000 watt lights require 3 separate 15 amp circuits. They also use 3kWh of electricity every hour (I iz reel smurt, huh?). The lights run 16-18 hours a day. Let's call it 17 hours. Here's the math:
3kwh*17hrs/day= 51kWh/day
51kWh*31 days = 1,581kWh/month.
Electric rate is $0.083566 per kWh
$0.083566*1581kWh=$132.12/mo

$132 per month just for the lights. *sigh*. That's more than what I pay for electricity for the entire house right now.

It's hard to believe, but it would be *way* cheaper to build a greenhouse, heat that, and just use the lights for supplemental lighting for a few hours in the morning and evening (when the sun is low in the sky in the winter).

So, why not do it? Firstly, it's not allowed by the HOA. Technically (according to covenants), you can't grow *any* food on the property. Secondly, I'm built into the side of a hill and the land has a roughly 35 degree slope, making any sort of out building impossible. With the house built, there is no place for earth-moving equipment to get in and level it out - it's a 25 foot near-vertical drop 6 feet from the side of the house.

I do have a few ideas, such as a screened-in balcony greenhouse where the second story window is for the upstairs bedroom, but this is a log home - the walls aren't easily modified as with a "normal" house.. they are 7.5" thick solid wood, and it's all load bearing.

I'll be throwing ideas around all winter to sort out how to handle this as running all these lights full time isn't a practical (or very earth-friendly) solution.

It's all just hurdles to be overcome, right?