well pumps ?

denn

 i just jumped in and started out by buying 9 355 watt panels, 47.45 voc.  i am intending to build it using 2 make  sky blue s340 and one 3kw all in one off grid tie, 24vlt 220.  my understanding is that  the more panels and charge controlers the fewer batteries needed.  my biggest draw will be the two 3/4 hp, 1495 watt 6.5 amp well pumps, and they are my biggest concern.  i do not yet know how to find the starting draw and dont know if a 3kw will handel the well pumps.  

mike95490

Here's a chart that should help.
Will both pumps start / run at the same time ever ?
Pumps run sunlight hours only ?
Are the pumps 2 wire ( starting cap underwater with the pump) or 3 wire - cap above ground in the control box.  3 wire starts a bit easier.
Is your chosen inverter a low-frequency or high-frequency inverter

My 1/2 hp pump, after starting and is running stably, logs 1,000 watts in use by the inverter.  That's includeing Power Factor  ( PF ) losses, copper losses and efficiency losses.

Having this be successful long term, at only 24V, is going to be rough.  What are the batteries, Flooded Lead Acid, Li,  ??

A low budget. 3Kw inverter, is going to be marginal at starting 3/4 hp

The minimal battery for a 24V system would be about 500Ah to keep the inverter happy, maybe 250ah at 48V , regardless how much solar is present.  Panels and charge controllers cannot respond to the 120hz peak power draw from the DC bus, batteries have to handle that.

denn

wow, lot to consider.  currently have 6 104ah  batteries planning on having 18 beforre start up, lead acid.  Reason for lead acid is availability, price and the rapid advancement of battery technology, hopefully by the time i replace them the sodium cells or nickle ion may be a better choice, and the shtf senerio, i live on a big lake with hundreds of bass boats loaded with deep cycle batteries.  The well pumps, along with most power consumption will be during full sun, overnight draw will be icebox and deepfreeze and some tv, occasionally.  i understand that 48vlt is better for big voltage but i dont want to go that way because of cost.  the 3500 watt inverter that i do have i plan on hard wireing for the fridge and icebox only, and if the 3kw msb will not run both well pumps then will get one for each pump perhaps.  See, im thinking that if i have a seperate inverter for everything along with several charge controllers then I can achive redundancy in the system itself as well as the batteries, and individual unit failures will not shut the entire system down.  i hope im being a little clearer about my understanding on solar to this point, and thanks a million for the chart.  My pumps are above ground 3 wire, however they are tagged at 6.5 amps at 220vlts, both 3/4hp, one pulls from the ground, the other provides increased pressure to house.     Dee

wellbuilt

That seams like a lot of hoopla , I just sunk a grundfos  pump down 670’ plus and it’s giving me allmost 6 gallons a minute  with no serge and it runs on 800 to 1000 watts
 I was going to run it on solar but it seam like a wast of power I’m just running it off my inverter for 1/2 hour a day in good sun and have 0 troubles the pump was a lot but in the end it was very east to set up with nothing extra to buy .   

wellbuilt

Ps 48 volt always  ends up being cheaper in the long run . 

mike95490

denn said:

....if the 3kw msb will not run both well pumps   ......     Dee

What is msb ?   I hope you don't plan to run motors on a modified sine wave inverter.  Bad for motor life.

MichaelK

If you don't know how to measure the starting draw of your pumps, then you really aren't qualified at this point to be building a system.  Take a few steps back and do a lot more research.  First off, get a clamp meter that can measure inrush current and learn how to use that.  Once you have a firm handle on the exact draws of each pump, then you can start to plan.

You mentioned an all-in-one, but most that I know of have little or no surge capacity.  A popular AiO, the MPP has only a 16 millisecond surge to 200%.  My Schneider inverter that I use for well-pumping can surge for 60 seconds to 200%.  My 1hp pump surges about 4X the running current.

Reading you responses really gives me the "design once build twice" mentality.  Don't spend another dollar on random stuff until you have a clear design goal in mind.  Resistance to going to 48V suggests to me that you are not ready yet either financially or mentally to tackle this scale of problem.

Really the first thing you should do is make an itemized list of everything you want to power, and how many watts they'll consume over the course of the day.  Take into account that the inverters themselves will be consuming power.  I've looked at other solar enthusiasts that found that their inverter was their single largest load that they were not even aware of.

denn

Thanks for the honest reply.  A lot of what you said i have learned over the last several days, thats how i do it, jump in and learn as i go, however a little more time on the research side of things wouldnt hurt.  i decided not to go with sky blue and choose Epever 60 watt for my first section of the system consisting of 4 355 watt panels, 40 amp breaker, 250 amp breaker and a 3500 watt pure sine wave inverter.  this section will run my 900 watt fridge and a 700 watt deep freeze and on sunny days my washing machine.  the battery bank is currently 12 104wh lead acid.  well, good or bad thats  whats getting built, inverter and breakers arrive next week, after i learn how to drive this unit, then ill grow from there.  again thanks for the reply.

BB.

Are the batteries 104 WH or 104 AH @ 12 volts (12 volts @ 100 AH is a typical size).

Have you figured out how many Watt*Hours (or kWH) per day you will need? 

And how many panels (Watts) are you going to use? And what voltage for the battery bank (12/24/48)?

Refrigerators and Freezers use a lot of energy in a home... If they are modern Energy Star Rated, something like 1,500 WH (1.5 kWH) per day EACH. And will this be a weekend or full time off grid installation?

Just to give you an idea of the math... Say 3,000 WH per day (2x fridge/freezer set) near Houston Texas:
http://www.solarelectricityhandbook.com/solar-irradiance.html

Houston
Average Solar Insolation figures

Measured in kWh/m2/day onto a solar panel set at a 60° angle from vertical:
(For best year-round performance)

Jan	Feb	Mar	Apr	May	Jun
3.53	3.87	4.65	4.98	5.20	5.20
Jul	Aug	Sep	Oct	Nov	Dec
5.40	5.24	5.19	4.75	3.93	3.51

• 3,000 WH per day * 1/0.52 off grid AC system eff * 1/3.51 hours of sun per day (December) = 1,644 Watt array for December "break even"

That would close for a "summer" system... But if you want to run in December, either larger array (upwards of 2x larger) or backup genset and fuel for bad weather...

This is a big jump in system specifications... Want to make sure you are OK with sun/genst/etc. for your needs....

-Bill

WaterWheel

Like Welbuilt said having a low start up surge pump like a Grundfos will cut your required inverter size by 2/3.

I was running my standard 1 hp well pump off my Conext inverter but the start up surge was so massive (somewhere around 8000 watts) it would occasionally trip a "low DC voltage" warning if I had another high load running after sundown.       I have since bitten the bullet and had the pump changed out to a 1 hp Grundfos SQ pump and it maxes out around 2300 watts draw.

This also means that if I ever need to use a generator to power the water pump I can get by with a much smaller generator.

wellbuilt

 2300 watts seams like a lot , I’m pumping from 700’ and use 700/1000 watts depending on how deep the water is in the well I get about 6 gallons a minute . 

 I can actually run my pump , charge the battery’s , and power he house on my 2800 watt Honda 

WaterWheel

You're right,     It's probably less than 2300 watts.       I only recently had the pump changed and haven't made a point of shutting everything down in the house and run the pump.      But the rating on the pump. was for 230v 9.8 amp.

wellbuilt

2300 watts would be a no go for me , I only have 120v in the house. 

 The sq pump is half the price of my SQF unit , but it sure makes  things easy . 

    I think the extra money is a  worth while expense as long as 5 or 6 gallons a min is enough water .