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 Post subject: Hi I need your help
PostPosted: Wed Jan 28, 2009 11:22 am GMT EthGMT 
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Fish Eggs
Fish Eggs

Joined: Mon Dec 22, 2008 12:20 pm GMT EndGMT
Posts: 5
I need your help. I have a well pump that I would like to run off of solar. The above ground pump is 17.5 starting and 8.5 running amps, 1 hp.

I have 2 - 60 watt kits from Northern tool, a sharp 80 watt panel and two 35ah ams batteries (that lose 0.3 volts overnight). Now it may sound like I know what I'm talking about, but I don't. I have gotten this far.

My Questions:
The 60 watt kits have a quick connect 4 to 1 to connect 4 - 15 watt panels together. Sunforce doesn't make a connector to connect the two kits, I think it might be a mc2 connector but I am not sure. Should I just wire it myself or is someone familiar with this connector and know where I can buy one? I can post a picture of it, if that matters

Is it any problem to connect the two kits and the 80w sharp together on a sunforce digital 30 amp controller?

The water pump probably starts for 15 seconds - definately less than 30 - and runs for 15 minutes to fill the pressurized tank 4 to 6 times per day.

I do not have an inverter. My initial thoughts are pure sine (as it is an important motor I am running) larger than needed, 2500 starting?


I want this system to work specifically in an emergency or even better always. And I do not want to burnout the motor either.

I am in North Carolina I seem to be getting 4 hours of direct sun per day, when it is sunny.


All suggestions and comments are welcome.
Thank you inadvance


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 Post subject: Re: Hi I need your help
PostPosted: Thu Jan 29, 2009 2:46 am GMT EthGMT 
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Guppy
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Joined: Fri Aug 04, 2006 10:24 am GMT EthGMT
Posts: 284
Location: Los Angeles
First, your pump runtime 8.5A x 120V = 1020 watts

1020 watts for 15 min, 6x a day is 90 minutes .
That becomes 1020 + 510 = 1520 Wh

Your solar panels, 60 + 60 + 80 = 200W x 4 hrs = 800Wh.

800Wh is about half of what you need to power the pump
( I did not add in system losses which run about 40% )


There are some DC powered solar pumps, that run much slower , but steady while the sun shines, and no batteries involved.

SG, correct me if I got the "rough" calculations wrong.

_________________
"Since the dawn of time it has been mankind's dream to blot out the sun"
Montgomery Burns


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 Post subject: Re: Hi I need your help
PostPosted: Sat Jan 31, 2009 2:11 am GMT EstGMT 
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Guppy
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Joined: Wed Apr 19, 2006 1:02 am GMT EthGMT
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Location: SF Bay Area
Plus the batteries are too small... Imagine trying to run the starter on your car for 15 minutes at a time (is not possible)... And that is an 80-100 amp*hour 12 volt battery.

Normally, we would suggest to size the battery for 3 days of no-sun and discharge to a maximum of 50% of capacity (for maximum life)... For higher power applications, I would suggest 24 volt inverter, minimum:

1520 Watt*Hours * [1/0.85 (inv eff)] * 1/24 volts * 3 days * 1/0.50 = 447 Amp*Hour @ 24 volts

Or, two 12 volt batteries with a minimum 447 amp*hour each in series to produce 24 volts nominal. Or, almost 10x the size of batteries versus what you currently have. This works about to roughly C/10 (1/10 the 20 Hour Rating) rating of the battery (the amount of load that would discharge your battery from 100% to 0% in 10 hours)... If you tried to use smaller batteries, you run the risk of damaging it from high discharge current (C/10 or C/20 is, roughly the optimum discharge rate, C/5 or C/1 might damage the battery--C/30 or C/40 is getting too expensive--rough rules of thumb).

In general, you want to use as small as motors and move as little water as possible--especially in an emergency. To size your system to power your normal "household use" (just a guess) in an emergency is, many times, not practical.

Regarding solar panels... you would assume that they are about 50% efficient, so:

1,520 WH * 1/50% * 1/4 hours of sun = 760 watts minimum... (recommend up to 2x more).

Solar Power, as a pure emergency backup, rarely makes sense... It is EXPENSIVE (solar panels + batteries), plus the batteries age anyways and will need replacing every 3-7+ years (depending on a whole bunch of things).

The better choice is to design your system to run on solar power all year long--with generator or utility backup (for bad weather or when more water is needed).

If you are just after emergency backup power--an appropriately sized generator (propane, natural gas, diesel, or gasoline) would make more sense.

When sizing the generator--it is pretty cheap to get some pretty large units (10kW-20kW are very common sold as "home backup" units--however, they can cost $1-$2 per hour to run--even if you are hardly using any power).

If you have natural gas or a large fuel tank (whole home propane)--it may not be a huge problem (not much fuel used, because few power failures)... However, if you have to bring fuel in 5 gallon cans--that can get old very quickly (5-10 gallons a day) or impossible to obtain (no power at service stations).

Try to size your loads to use a smaller generator (I really like the Honda eu2000i). It can easily supply smaller loads (fridge, some CFL lights, radio, TV) for a couple gallons per day... Much easier to store a reasonable amount of fuel (10-20 gallons with fuel stabilizer, another 10-20 gallons from your car, etc.).

If you have heavy loads the run for a short time, like a well pump... You can have the 5kW noise maker run for 15 minutes to get your day's worth of emergency water, and use the smaller (and quieter) 1,600 watt generator to run the rest of the loads.

-Bill


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 Post subject: Re: Hi I need your help
PostPosted: Tue Mar 03, 2009 10:49 am GMT ErdGMT 
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Fish Eggs
Fish Eggs

Joined: Mon Dec 22, 2008 12:20 pm GMT EndGMT
Posts: 5
Thank you for your input. I have a gas generator and I want to stop storing enough gas.
It is a 3500/5000 and can run the pump, coffee maker, furnace fan and a few lights.

So I guess I have been basing my minimal needs off of the above working. It is plugged directly into the house.

Again. I have more information. The pump is 17.5 Amp ! I now know that the plate 17.5/8 is related to
the voltage and I am running 120 not 240.

So the math to me looks like this - keeping it simple - 1 hour (I've timed it and the pump runs about 6 minutes at a time.)

2100 watts running on a 2500 / 5000 pure sine inverter that is 90% efficient plus an additional 210 for loss = 2310 watts.

If I am using 12 volt batteries (because my solar panel say they are a 12 volt system) then I am looking at 192 round it up to 200 amps.

Recap - I have 200 watts of solar paneling - which I know is not enough plus 2 - 51 amp batteries again not enough

Any help is appreciated. Sure I would love to have this run full time and only use the generator when necessary and store less gas.

Please help before I start to make some real financial mistakes. I can still return the inverter.

Many Thanks

SolarLady


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 Post subject: Re: Hi I need your help
PostPosted: Tue Mar 03, 2009 1:08 pm GMT ErdGMT 
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Guppy
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Joined: Wed Apr 19, 2006 1:02 am GMT EthGMT
Posts: 110
Location: SF Bay Area
I am still at a bit of a loss--Are you:

1. trying to convert your entire home to run off of off-grid solar and disconnect your AC mains?
2. trying to build an emergency system to power you for XX days after an ice/wind storm or hurricane?
3. Are you trying to save money/go green?

If you have grid power--any off grid and/or emergency backup solar system will never save you money--especially if you want it to run your entire home off-grid.

If you are trying to save some money/go green--first place to go is conservation. Reduce you power needs through insulation, energy star appliances, less use of power.

After you have done your work on conservation--you will need to understand your power usage--looking at your monthly power bill (and how much it changes by season), and at your loads (sizing the system to be large enough to start your pump and run your microwave, etc.). And at your home/site--do you have a large area with no shade between 9am-3pm (at least) all year round (East or West facing systems can work too--but are a bit less efficient).

There are some very nice systems out there that can give you solar power at a pretty good price. Grid Tie / Utility Interactive Inverters+Solar panels, no batteries--best kWhr per dollar spent, most efficient, least amount of maintenance. However, no emergency power capability. Lots of rebates and tax breaks available. Requires approval by your local building department and power company to install.

There are very nice hybrid power systems that do both Grid Tied and will supply off-grid power in an emergency. You can size the battery bank for a day of no power--with generator backup--or you can add more batteries for the ability to run off-grid for long periods without needing a backup generator.

Either of the above systems will need a person at your place that knows what they are doing--to help you decide what system you want/need--and to do the engineering, pull permits, and install it safely.

A full off-grid system usually only makes sense if you are in an area where there are no utility lines (or the lines would cost tens of thousands of dollars to run to the home).

Just to give you a very rough idea of the costs for electric power (assuming turnkey install, national average costs, no property taxes, etc.--prices are falling on solar panels, if you can find deals for parts, contract the labor yourself, you can save some money):

$0.10-$0.30 per kWhr -- typical cost of utility power
$0.10-$0.35 per kWhr -- typical cost of Grid Tied Power (after rebates--assuming 20+ year life)
$1.00-$2.00 per kWhr -- typical cost of Off-Grid Power (typically no rebates, 20 year life, but need battery replacement every ~5-10 years)

Remember, you are building your own power station--and need it installed correctly/safely, and want a 25+ year life out of it. Depending on how much power you need and local conditions (how much sun you get, any local shading, etc.)--this is a $10-$50,000+ project to add solar PV to your home.

And if it fails--you will be the one respon$ible to get it fixed and working again.

-Bill


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 Post subject: Re: Hi I need your help
PostPosted: Tue Mar 03, 2009 2:36 pm GMT ErdGMT 
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Fish Eggs
Fish Eggs

Joined: Mon Dec 22, 2008 12:20 pm GMT EndGMT
Posts: 5
Hello thank you for your feedback.

I am looking to have a backup emergency power only for the 17.5 amp jet well pump.

Last time I was in a bad winter storm water was my only problem.
My current emergency generator is gasoline and I do not want to store 3 days of gas if I don't have too.

I can locate the panels so that they get 5-6 hours of sun per day.

My appreciation in advance


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 Post subject: Re: Hi I need your help
PostPosted: Tue Mar 03, 2009 5:48 pm GMT ErdGMT 
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Guppy
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Joined: Wed Apr 19, 2006 1:02 am GMT EthGMT
Posts: 110
Location: SF Bay Area
I am not on a well--so take what I say with a grain of salt...

Jet Pumps tend to be very inefficient anyway... Depending on your flow rate, storage, etc.., a down the hole pump, or other direct pump (instead of jet) will save you a lot in electricity, and in the amount of power you will need to generate for your well pump.

Also, as you change your requirements, you might find a pump that will meet your needs when run from solar--even without a battery bank--and use the AC mains (or a generator) as backup.

Solar, makes the best economic sense when used all year long. Ideally, pumping with a small capacity solar power pump into an elevated tank--or above ground tank, with a simple pressure pump (AC driven) for house pressure (you could place a smaller DC pump in parallel with the AC pump and run it from solar/batteries/solar panel--just large enough to keep water pressure in the home for 1 faucet/shower for emergency use).

It sounds like you have a pressure tank (something like 40-80 gallons with an air bladder/air chamber?)?

If you can design a solar pump system that runs a low flow rate 6-8 hours per day into a cistern (straight solar panel with backup power source), and a standard AC pressure pump with small backup solar pressure pump (running from solar/battery/backup power)--you would 1. save money in day to use in reduced utility power costs, 2. maximize the return in solar investment (minimum solar panels, used year round), and 3. small enough secondary pressure pump to run your house in an emergency.

If you end up needing a large in ground/above ground pump that runs on demand--then solar+batteries would, probably, have to be the answer. When you add batteries, the costs and maintenance requirements go up.

What are the specifics of your well (depth, diameter, flow rate). And what is your ability to store water above ground and daily needs (irrigation, house hold use, etc.)...

Solar Guppy would probably be able to give you some better ideas (and better questions).

-Bill

PS: If you can get your well pump requirements down to 1 hour per day and run on a 1,600 watt generator (like a Honda eu2000i)--5 gallons of fuel would last you well over 3 days (depending on if you want to start the generator every time you need to refill your pressure tank or not).

The Honda can run almost 4 hours on 1.1 gallons of fuel (1,600 watts), or close to 15 hours at 400 watts on 1.1 gallons of fuel.


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 Post subject: Re: Hi I need your help
PostPosted: Wed Mar 04, 2009 9:29 am GMT EthGMT 
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Fish Eggs
Fish Eggs

Joined: Mon Dec 22, 2008 12:20 pm GMT EndGMT
Posts: 5
I would really like to know what the requirements are to set this up with solar full time or emergency.

Again the jet pump runs for about 1 hour a day at 17.5 amps.
I have a 2500/5000 pure sine inverter and 200 watts of solar panels.

Any help is really appreaciated.


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 Post subject: Re: Hi I need your help
PostPosted: Wed Mar 04, 2009 2:33 pm GMT EthGMT 
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Guppy
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Joined: Mon Mar 20, 2006 7:58 pm GMT EthGMT
Posts: 214
Location: pittsburgh
i think your best bet is the generator in an emergency but your wish to have a backup other than a generator is ok too. what you need in general is an inverter/charger (charger portion is powered by the grid) sized large enough to cover all of the loads and surges you'd expect. the batteries will need to supply this power for say 3 days without dropping the depth of discharge below 50%. you can make this larger to last longer if the charger can supply a minimum of 5% of the battery bank ah capacity.
as to solar charging this you could do it, but it isn't practical unless you expect the grid to go down longer than the backup power can supply. this might be hurricane or ice storm circumstances where the power can be out for weeks and i would be more concerned with such things as my furnace or refrigerator and this can be done this way too if all of the loads are accounted for and your inverter/charger and batteries are sized accordingly. the pvs must supply all of the power needed plus extra due to losses and efficiencies, not to mention clouds for those extended emergency times. keep in mind that you would use those loads even during the night and you must account for the entire 24hr period of loads and also what sunpower you would also typically get in a day as it must be larger than the loads. this could be 5-6 hours of full sun for the pvs in the summer, but can be much less in the winter and varies per location and time of year. i would not keep getting those little pvs from northern tool as you would be better off with the larger and better made pvs like sun electric or northern arizona wind & sun might sell.


Last edited by niel on Thu Mar 05, 2009 9:15 pm GMT EthGMT, edited 1 time in total.

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 Post subject: Re: Hi I need your help
PostPosted: Wed Mar 04, 2009 4:57 pm GMT EthGMT 
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Fish Eggs
Fish Eggs

Joined: Mon Dec 22, 2008 12:20 pm GMT EndGMT
Posts: 5
Thank you all for your information. I really appreciate it.


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