Solar powered forced air compost pile

ZooMan · March 2010

I’m ready to start my solar project for an aerated compost piles. There is a company that has systems ready to go. I’m just getting parts from O2Compost so there technical support is going to be limited.
They do offer a solar option so I know it will work.
http://www.o2compost.com/content/Solar.htm
http://www.o2compost.com/content/MicroBin.htm
I’m looking at a 1/4 HP High Impact Plastic Blower: $126.00
On-Off: Cycle Timer $104.00
These are supplied by O2Composting.
I will be getting one of 12 135 watt panels
Kyocera Solar KD-135 135 Watt 12 Volt Solar Electric Panel
http://store.solar-electric.com/kyso130wa12v.html
BZ Products MPPT250 250 Watt MPPT Solar Charge Controller
http://www.discountpv.com/charge_controllers/mppt250.htm
I have an unused 120 amp hour lead acid battery that I can start with.
I need to find an inverter that will work with this system.
I know the BZ MPPT is not going to be something you would recommend.
I was able to find a few blowers and cycle timers that would work and are also 12v , but I need to make sure the motor can do a steady cycle on and off, these cycles can be as short as 2 minutes on and 5 off temp is the guiding factor.

I’m going to make a panel mount and a box to house the various components.
Thanks in advance
Ken Scofield

higgins · March 2010

Re: Solar powered forced air compost pile

I'm a relative begginer in the world of solar composting,but my opinion about this project is that for composting it is quite expensive and you may be buying a lot of equipment that could be more efficient for another type of project.Composting is usually leave it a while,then manually turn it over to allow air in etc;Are there any benefits or advantages other than speeding up the air flow to break it down faster?
Higgins

peterako · March 2010

Re: Solar powered forced air compost pile

I think this is a lot off wast energy. You will dry out or cool down the compost to fast.

I am using for years a system from old wood in a box shape whit holes in the bottum it takes two to four weeks to have compost filling in the top removing in the lower part.

Use the solar panel and battery for garden lights.:D

Greetings from Greece

russ · March 2010

Re: Solar powered forced air compost pile

Hustlers trying to cash in on the green thing.

İ don't think that is even how compost works.

Cariboocoot · March 2010

Re: Solar powered forced air compost pile

Please stop before you waste your money.

I've gardened for more years than most of the members of this forum have been alive, and have never yet needed forced air to make compost. In my opinion this whole procedure is unnecessary.

Beyond that, a couple of warning flags crop up:
BZ charge controller. Their reputation is bad. Search this forum and see how many positive comments you can find about their equipment.
Systems that are "ready to go" are quite often poor value. Most are "ready to go" to the dump right after you discover they don't live up to their claims.

Trying to force air through decomposing waste via a fan is likely to be not very effective for making compost. There's more to it than just adding air. As Peterako mentioned, what about the moisture? Nor will this 'circulate' the micorbes involved.

Save your money; buy a pitch fork.

ZooMan · March 2010

Re: Solar powered forced air compost pile

Sorry to be sort with you, but this enquiry was about the inverter recommendations and not about the merits of composting. I do compost about 15-20 cubic yards pine shavings a month along with horse manure that’s removed the 10stalls, it’s kept in 3 large piles that are static, no room to turn. I have had this system in place for the past 10 years. We have increased our stalls from 7 to 10 and need to increase the efficiency and quality of compost that I’m producing now.
This is a proven and Easley maintained via aeration, one of many links.
http://www.magicsoil.com/index;_2009_backup.htm
My current piles are 8’ wide 5’ high and 18 long I have already installed the vents in them and are ready to go, Static piles are big producers of C02 and not that much of a friend to the environment. In south FL sugar sand is our biggest enemy of our pastures. ENOUGH! Rant stopped.
My wife and I work full time on our very successful horse training facility in south FL.

peterako wrote: »

I think this is a lot off wast energy. You will dry out or cool down the compost to fast.

I am using for years a system from old wood in a box shape whit holes in the bottum it takes two to four weeks to have compost filling in the top removing in the lower part.

Use the solar panel and battery for garden lights.:D

Greetings from Greece

russ wrote: »

Hustlers trying to cash in on the green thing.

İ don't think that is even how compost works.

Cariboocoot wrote: »

Please stop before you waste your money.

I've gardened for more years than most of the members of this forum have been alive, and have never yet needed forced air to make compost. In my opinion this whole procedure is unnecessary.

Beyond that, a couple of warning flags crop up:
BZ charge controller. Their reputation is bad. Search this forum and see how many positive comments you can find about their equipment.
Systems that are "ready to go" are quite often poor value. Most are "ready to go" to the dump right after you discover they don't live up to their claims.

Trying to force air through decomposing waste via a fan is likely to be not very effective for making compost. There's more to it than just adding air. As Peterako mentioned, what about the moisture? Nor will this 'circulate' the micorbes involved.

Save your money; buy a pitch fork.

Cariboocoot · March 2010

Re: Solar powered forced air compost pile

Well if you're satisfied with the results you get now, fine. When I did composting in this volume we turned it over with a front-end loader.

As for supplying the electrical needs via solar, one 120 Amp/hr batter and a 132 Watt panel aren't going to supply much power even under the best conditions. The BZ controller will probably quit shortly after it's installed, although many of them don't work straight out of the box.

So you need to know how many Watts your fan(s) require and how long they will be running for. The fan may be rated at 1/4 HP, but that doesn't necessarily mean they will draw <200 Watts. The frequent cycling is also a problem, as motors draw more on start-up. If you had an existing system you could plug a Kill-A-Watt meter into for a month you'd get a good idea of the average daily power requirements.

But consider this: battery-based solar power systems produce electricity at a cost o around $1 per kW/hr over the lifespan of the equipment. Now how much are your local utility rates?

Pardon our collective skepticism here, but we've all seen too many cases of people getting ripped-off by solar-powered wonder gadgets that usually just plain don't work! We try to keep people from getting robbed whenever possible, so the cynical attitude runs high around here.:p

ZooMan · March 2010

Re: Solar powered forced air compost pile

Turning is just about useless, o2 will be gone in a matter of minuets. but it does give you access to add water evenly. The system has nothing to do with electricty coasts, there is no serevice at the end of the property. As far as the battery goes that can be modified. I'm starting to see if it's not on the forums store list its going to get slammed. I just asked for an inverter recomundation..
I see this thred is going noware fast..

No time for the spell checker. Sorry

Cariboocoot wrote: »

Well if you're satisfied with the results you get now, fine. When I did composting in this volume we turned it over with a front-end loader.

As for supplying the electrical needs via solar, one 120 Amp/hr batter and a 132 Watt panel aren't going to supply much power even under the best conditions. The BZ controller will probably quit shortly after it's installed, although many of them don't work straight out of the box.

So you need to know how many Watts your fan(s) require and how long they will be running for. The fan may be rated at 1/4 HP, but that doesn't necessarily mean they will draw <200 Watts. The frequent cycling is also a problem, as motors draw more on start-up. If you had an existing system you could plug a Kill-A-Watt meter into for a month you'd get a good idea of the average daily power requirements.

But consider this: battery-based solar power systems produce electricity at a cost o around $1 per kW/hr over the lifespan of the equipment. Now how much are your local utility rates?

Pardon our collective skepticism here, but we've all seen too many cases of people getting ripped-off by solar-powered wonder gadgets that usually just plain don't work! We try to keep people from getting robbed whenever possible, so the cynical attitude runs high around here.:p

BB. · March 2010

Re: Solar powered forced air compost pile

This Morning Star 300 watt / 600 watt surge would be a very nice inverter for what you need... You may need a larger inverter if the fan motor has high starting current (heavy fan assembly or something):

Morningstar SureSine, 300 Watt Sine Wave Inverter 115VAC

You can hook your timer to the remote power switch input to the SureSine inverter... This will save a lot of power of not having an idling inverter by turning off the AC power.

Our host has larger inverters if you need them (some have inhibit switches, or also have "search mode" to save power too).

To be honest though--how much power are you planning on needing to run the fan. A single 135 watt solar panel will provide this amount of AC power during a sunny summer day of 5 hours of full sun:

135 watts * 5 hours of sun * 0.52 system eff = 351 Watt*Hours
1/4 HP * 746 watts * 1/0.80 motor eff = 233 watts (guess)
351 WH per day / 233 Watts = 1.5 hours of operation per day

There are a lot of other issues too--You need to protect the battery from over discharge, you need to get the battery fully charged every few days for long life, etc...

A good place to start would be to have you measure with a Kill-a-Watt Meter how much power you plan to use.

If you have a lot of piles to aerate--It may be worth the money to run Utility Power to your site... Solar is a very expensive solution for driving motors.

Another possibility is to run DC motors/Fans directly from the panels--if you only need power when the sun is out--you save the price (and losses) of the batteries and inverters. Again, how much on time you need for the fan will determine if that is a cost effective solution or not.

-Bill

BB. · March 2010

Re: Solar powered forced air compost pile

ZooMan,

Sorry for the hard feelings... Most of the people here want to see you happy with whatever solution you end up with.

And, we are, in general, cheap. Conservation, alternative means of performing the operation with non-solar power, etc. are all suggestions that we make here every day...

In the end, battery powered off-grid solar will cost $1-$2+ per kWHr by the time all the costs and maintenance (such as replacing batteries every 3-8 years or so) are taken into account. Most people pay only 1/10th that amount for utility power--so the cost of running poles/trenching utility power to the point of use is frequently still the most cost effective solution.

If you want to offset power use--a Grid Tied system (solar panels and a GT/Utility Interactive Inverter) is a good way to achieve both cost effective power and conserve resources in the longer term.

The suggestions and questions are from the heart--we don't want to see you spend anymore than you have to for your solution.

-Bill

mike95490 · March 2010

Re: Solar powered forced air compost pile

I concour with the Sure Sine, with the duty cycle you list, it should handle a 600W starting surge fine (rated 600W for 10 minutes)

But your single 125W PV panel will NOT be enough.

1/4 hp = about 200W consumed @ a 30% duty cycle 24/7 (2on/5 off)
200W in 24Hours = 4800wh @ 30% =1600 Wh consumed
PV generates 100W for 5 hours = 500Wh generated.

You will need at least 6 of the 125w PV panels, and that will barely hold you through a week of sunny days
(I'm accounting for PV, charger, battery, inverter losses here)

Your battery requirements:
1600Wh /12V = 133Ah from your battery. You seldom want to deplete your battery more than 30% or lifetime becomes very short, the deeper the cycles, the fewer the battery has. At 50%, you might get a years worth out of 2 batteries in parallel.

You do not want a blower with a brushed motor, they are fine for a disposable blow dryer, but not for a long life 24/7 application

CaptTurbo · March 2010

Re: Solar powered forced air compost pile

It sounds like an interesting project to me but perhaps he just needs to upscale the array and battery size. Making compost fast and efficiently is hard work.

I'm an avid SW Florida gardener and compost is the life blood of gardening succes since this sugar sand can't grow much on it's own.

I used the large sized Compost tumbler for five years. It really did produce good compost in two weeks if I turned it (by hand crank) each day. I was thinking about using solar power to do this chore for me but the darned tumbler rusted out just as the five year warranty expired. :grr

I know this is smaller scale then the OP is needing but if I could find a corrosion resistant tumbler I think one panel and one battery could power it fine since it would only need to rotate about three minutes per day.

Solar powered forced air compost pile

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