Tuesday, June 7, 2011

Rain Barrels on Crack

I built a rain barrel setup a few years ago for my garden / yard, complete with a rather powerful electric pump to provide some needed water pressure for a spray nozzle, sprinkler, extra-long garden hose, or what have you.  I wasn't really trying to be green when I put this sucker together, I just wanted to save some damn money on my water bill.  Little did I know, the electric pump I used with the barrels would cause a serious uproar with my neighbors - I got a lot of: "Well that's not very green...using electricity to pump your rainwater!" and of course the: "Are you really saving any money on water when you're paying for the electricity to use that pump?!" and the ever-popular: "If you spray my kid in the face one more time with your 70 psi f*&%ing rainwater I'm gonna sue!!"  Not gonna lie, that pump was really pissing people off.  So I decided to add a solar / battery power system to the whole setup and make it TOTALLY green.  

Or sort of a fiery-red?

So.  Back up a few years to the process of building the rain barrels themselves.  To start, I poured a small concrete slab for the two 55 gallon food-grade poly barrels I found on Craigslist.  Went with plastic since it obviously doesn't rust, and clear so I could see the water level.  Of course after a month or so of water sitting in 80 degree heat, a nice coat of algae formed on the inside of the barrels, rendering sight a little difficult...but not impossible.  
The barrels are fed by one downspout, which to my surprise provided plenty of water.  Just an hour of moderate intensity rain will fill both barrels.  Heavy rainfall, a matter of minutes.  I fashioned a removable pre-filter to catch leaves and other large debris by epoxy-ing a wire downspout mesh into a 4x2 PVC pipe reducer.  The hole in the top of the rain barrel is just large enough to accept the 2-inch side of the reducer, and the gutter downspout sits right inside the 4-inch part of the reducer. 

VoilĂ .  I should patent this shit.

Downstream, I used flexible PVC pipe to join the barrels and connect them to the pump via a line strainer.  This single pipe serves as both the fill and the discharge from the second barrel and keeps the water level in each tank the same via hydrostatic equilibrium.  The actual connection from the pipe to the plastic barrels was made through an iron pipe nipple.  This does two things - threading it directly into the barrel makes a tight seal that doesn't require any additional sealing or gaskets, and it allows for detachment of the hoses from the barrels.  You can almost see it here - 

Like how you almost made the A team.

I included a PVC union between the two barrels and another before the pump / line strainer to allow for disassembly and drainage at the end of the season.  Both barrels have a small opening at the top for air venting. The line strainer has NPT pipe threads and a removable canister which houses a stainless steel mesh screen filter.  The pump is a handy dandy little Dayton Utility Pump purchased from Grainger, the specs can be found here.  

I may not look like much, but I'm a pro at pretending to be a ninja.

Essentially everything is connected by an assortment of PVC solvent-welded fittings, PVC unions, and threaded fittings, including the piece of flexible PVC from the discharge side of the pump up to a tee fitting that feeds into two hose bibs - one on each side of the fence.  

The valve is just there for Feng Shui.

Overflow is handled by a 2 inch PVC pipe attached at the top of one of the barrels, also through an iron pipe nipple, as shown here - 

"If you're gonna spew, spew into this."

The PVC pipe feeds into a flexible rubber hose which simply runs around to the front of the barrels and discharges away from the house.

Here's the whole setup - 

So...back to the solar power / battery arrangement.  Essentially, the solar panel will charge a 12 volt battery and an inverter will convert the 12 volt DC battery power into 120 volt AC in order to run the pump.  I found a 15 watt @ 12 volt solar panel on Ebay for around $50, and a permanent-mount 1000 watt inverter for even less.  The pump motor draws 6.5 amps @ 120vAC, so using Watts Law this equates to about 800 watts.  The inverter is capable of delivering a 2000 watt surge, so a little extra current draw required during motor start-up shouldn't be a problem.  Here she is -   
Yes, she's a she.  Her name is Susie. 

The battery is a 12-volt commercial type, and is similar in size and shape to a automotive battery, but has 5/16 inch threaded studs as connecting terminals instead of clamp-style posts.  The solar charge controller shown below will keep the solar panel from overcharging the battery. It even has three indicator lights in a stoplight-like configuration - Red: Solar Power Available, Yellow: Charging, and Green: Charged.

"I live my life a quarter watt at a time."

To get the most exposure, I mounted the south-facing 38x12 solar panel on a treated 4x4 post in the backyard, next to the existing eye-sore, my satellite dish.  Unfortunately, the rain barrels are on the north side of the house where there's practically no direct sunlight, so I couldn't put the panel near them.  I made a mounting bracket arrangement out of 1 inch aluminum angle iron that would allow for pitch adjustment of the solar panel throughout the year.  To catch the most sun in the summer months, the panel will be about 25 degrees from horizontal.  In the winter, around 65 degrees. 

To make the run back to the house, I buried 16 gauge outdoor "landscape cable," which I found at the local home improvement store for about $16 per 100 ft length.  Cheap and bury-able. 

'Nuff said.

Since the inverter had to be kept dry (and reasonably cool) I decided to mount it, along with the battery and charge controller, inside the house.  Conveniently, just on the other side of the wall where the rain barrels reside, is the laundry room.  I cut a few pieces of 3/4 inch particle board for a mounting base / shelf for the components and fastened it to the wall in a location where it would be visible but out of harms way - 

Right above the beer fridge in case Susie gets thirsty.

I wired the inverter to the battery with #4 copper battery cable with ring terminals.  Large conductor wire was necessary since at full load the inverter will draw close to 100 amps from the battery.  (1000 watts / 12 volts = 83.3 amps x 20% efficiency loss = 99 amps)  The solar panel supply cable is connected to the charge controller, which is then also connected to the battery.  Here's a closer view - 

The solar panel supply and 120 volt return pass through the wall (just below the shelf) through 1/2 inch EMT conduit and into the switch and outlet mounted outside - 

The solar panel supply cable exits through the bottom of the outlet box and makes its way out to the solar panel in the back yard.  The lower receptacle of the outlet (where the pump is plugged in) is switched by the above weatherproof toggle, while the upper receptacle is "always on."  The painted outlet box to the left is the existing, mains-powered outlet.  

And that's about it!  A complete, self-sustaining pressurized water supply for my entire garden / yard that uses no fossil-fueled electricity or city water resources.  As an added bonus, the inverter (and battery) is large enough to power just about any appliance, electronic, or light in the house (except the A/C or the stove/oven for instance) so when the power goes out, guess who will still be watching re-runs of Sister Sister?  That's right.  This guy.  

Take that, neighbors.