Powering a home garden sprinkler with solar?

System

I'm involved with a local homeowner's association and we have a small residential pump system irrigating our landscaping. It consumes about 5 kilowatts of electricity per month. The system is a "Rainbird professional ESP 6-LX", which the internet tells me takes an input of 120v, 60hz (the key to the lockbox also has a warning to only connect to a 120v +/- 10% power source).

The local power company just jacked up our rates so that we're going to have to pay about $250 a year for that fifty-three-cent-a-month's worth of electricity (they're charging us a commercial base rate, as I understand it).

How much would it cost to power that pump system with a solar panel instead, and take it off-grid? Could y'all point me in any good research directions on this question, or is what I'm considering not feasible?

Any help appreciated. Thanks!

Cariboocoot

Re: Powering a home garden sprinkler with solar?

Before you go jumping off-grid, as it were, you should know that a typical off-grid system produces power at a cost of $1.00 or more per kilowatt hour over the lifespan of the system. Furthermore they require space and periodic maintenance. To replace your existing watering system with a more "solar friendly" set-up that would reduce the size requirements of the solar would involve further capital expense.

Now how bad do those commercial electric rates look to you?

icarus

Re: Powering a home garden sprinkler with solar?

IF you are REALLY only using $.53 per month, than it should be pretty easy to solve with Pv. However, before you go to far down the road, load at your REAL consumption numbers, either with a Kill-a-watt meter, or look at your electric bills averaged over a year or so.

Good luck, post more when you know more.

Tony

PS. If you are only using $.53 per month that is only about 4 kw per month, or .13 per day. Question is, what are you powering, just the control panel and some solenoid valves? No pumps? It sounds like the "Rainbird" is a control panel. Get a Kill-a watt ans see what it draws. Then check back.

mike95490

Re: Powering a home garden sprinkler with solar?

Thornwell wrote: »

I'm involved with a local homeowner's association and we have a small residential pump system irrigating our landscaping. It consumes about 5 kilowatts of electricity per month. The system is a "Rainbird professional ESP 6-LX", which the internet tells me takes an input of 120v, 60hz (the key to the lockbox also has a warning to only connect to a 120v +/- 10% power source).

The local power company just jacked up our rates so that we're going to have to pay about $250 a year for that fifty-three-cent-a-month's worth of electricity (they're charging us a commercial base rate, as I understand it).

How much would it cost to power that pump system with a solar panel instead, and take it off-grid? Could y'all point me in any good research directions on this question, or is what I'm considering not feasible?

Any help appreciated. Thanks!

1) Are you sure there is a PUMP in there. Rainbird makes Timers, that draw hardly any power at all. If there is no pump, a group 27 AGM battery, controller, and a 200W panel should keep it happy. Look at it's wall wart, and you might even be able to power it off 12V ! If it needs 120VAC for a 24VAC valve system, well, a SureSine should be able to do that, Whole thing for less than $2K

BB.

Re: Powering a home garden sprinkler with solar?

Another possibility--If the $250 a year works out to be the minimum connect charge with the utility (meter+billing)--If there is an existing condo meter nearby that can be spliced to instead. Give the Condo owner $5 per month credit for the power usage -- and everyone is happy.

We did this for water on an apartment--Just was not worth connecting another city water tap to irrigate 500 sqft of grass.

-Bill

peakbagger

Re: Powering a home garden sprinkler with solar?

Assuming that the system truly draws 5 kilowatt hours per month. This lines up with a rate of 10.6 cents per KW hour @ 53 cents per month. If that is correct, thats a 6.9 watt hour load 24 hours per day. With a consumption like that, what you are doing is supplying power to a irrigation timer controller not a pump (which would draw a lot more). I expect that there is a solenoid valve in the timer that draws a somewhat higher load intermittently.

Given the low load and non critical nature, it sounds like all you need is a battery, a solar panel, a charge controller with a Low Voltage Disconnect and a small true sine wave inverter. You may even be able to get away with a cheap modified sine wave inverter, you can buy at walmart, but the power supply in the timer may not be happy or functional if it depends on the sine wave for a timing pulse. If you could get a 12 volt irrigation timer, it would even simplify things a bit more.

Probably the biggest hassle is keeping someone from stealing the equipment as it would be attractive to thieves.

dwh

Re: Powering a home garden sprinkler with solar?

mike90045 wrote: »

1) Are you sure there is a PUMP in there. Rainbird makes Timers, that draw hardly any power at all. If there is no pump, a group 27 AGM battery, controller, and a 200W panel should keep it happy. Look at it's wall wart, and you might even be able to power it off 12V ! If it needs 120VAC for a 24VAC valve system, well, a SureSine should be able to do that, Whole thing for less than $2K

You're right about that - there is almost certainly no pump in that system.

The RainBird timers generally don't have a wall wart - they usually have a 1/2" ko to which you can either hard-wire it with conduit or install a pigtail cord.

http://www.horizononline.com/products/showproduct.phtml/ESP6


They use an internal transformer to put out the 24v for the valves:

http://store.rainbird.com/shopexd.asp?id=1223


RainBird also makes battery operated controllers:

http://www.rainbird.com/landscape/products/controllers/tbos.htm

and the now discontinued:
http://www.rainbird.com/landscape/products/controllers/easyrain.htm


There are other manufacturers of battery operated irrigation controllers:

http://www.sprinklerwarehouse.com/Hunter-Battery-Operated-Single-Valve-Controller-p/svc-100.htm

westbranch

Re: Powering a home garden sprinkler with solar?

also NELSON products. I have used their stuff for 20 years so far with the usual service needs...

http://www.lrnelson.com/root/instructions

Eric