48V Off grid system for down payment on 6 Acres help

BB.

Re: 48V Off grid system for down payment on 6 Acres help

No, I was looking before for this information (last year):

http://www.rc-electronics-usa.com/meter-faq.html#faq2

Oh--and it only counts up in one direction... Reverse current flow is not logged at all.

[h=2]About measuring current flow in both directions (e.g. bi-directional measurement)?[/h] The "Watt's Up" and Doc Wattson meters only measure current flowing in the black (negative) wire from their LOAD side to their SOURCE side as labeled on the meter's case. Current flowing in the opposite direction is not measured and does not affect accumulated or peak readings. Current flowing in the red wires is not measured at all.
To do a net current flow "bi-directional" current measurements (e.g. measure both directions of current flow) at one point in a circuit, we recommend using two meters connected together and oriented LOAD to LOAD (or SOURCE to SOURCE) as that is a more flexible and easily interpretted arrangement, than a bidirectional meter usually offers.
Alternatively, the meters can be mounted in separate parts of the system to measure two currents simulaneously. For example, the charge current into a battery and the discharge current out. Those currents may differ and this arrangement will show that. In this case meters are connected as usual ensuring that the current to be monitored is flowing in the correct direction in the black leads.
These dual meter arrangements allow independent measurement of the two current flows and their peak values. It also allows their respective accumulated values (e.g. Ah, Wh) to be reset separately. A bonus is that the voltages of the two separate systems can be independently monitored as well as the currents.
Note that with the dual systems, the red wires can also be connected using the "3-wire" arrangement. The red wires only need to carry enough current to power the meters and measure the voltage at the desired points.

-Bill

gww1

Re: 48V Off grid system for down payment on 6 Acres help

Will the outback system with 5600 watts+ and with a 48 volt battery bank overpower the doc watson and if I tried to salvage what I have already bought would buying another one give me a fairly decent battery managment system? I paid $103 for mine cause I bought a heavier exterior shunt to change the interior one to make it more robust. can I get something decent for another one at $53 plus shipping?
Thanks
gww

chevenstein

Re: 48V Off grid system for down payment on 6 Acres help

To the OP's original questions: I have a similar deep well pump that I run off grid with the system in my signature and have borrowed a fancy industrial motor troubleshooting ammeter to see that the startup load on the DC side for my pump is over 500 AMPS. My battery bank and inverter can barely start this thing even with 2/0 wire on the DC side, let alone run the well pump for an extended period of time (tens of minutes would be a stretch on fully charged batteries due in part to the Peukert effect: http://en.wikipedia.org/wiki/Peukert's_law ).

I would consider replacing the pump itself with a model that can be soft started and/or a DC model that can run directly off of the array, depending on how the well is to be used.

PS - I would not use homemade panels for cost, safety, and longevity reasons.

gww1

Re: 48V Off grid system for down payment on 6 Acres help

Chevenstien
How quikly does the 500 amps drop to a more reasonable level after start up. I also have a deep well.
gww

PS I also have 2000 watts homade panels and have bought 2800 watts at 94 cents a watt. I can't build them that cheep and the are not as good.

BB.

Re: 48V Off grid system for down payment on 6 Acres help

So far, the best "entry level" battery monitor (from comments on this forum) still seems to be the Trimetric at ~$152... Anything else is going to cost more (I believe, I am not in the solar biz, and I do not work at/for NAWS).

-Bill

chevenstein

Re: 48V Off grid system for down payment on 6 Acres help

Gww,
The 500A draw is momentary (< 1 second) then falls to about 40 when the pump is running. Note that when I had half of my battery bank (220AH @ 48V) on 6 gauge temporary wiring the voltage drop on the AC side was so bad when the pump started that most other AC loads connected would shut off when the well pump started.
Chevenstein

Blackcherry04

Re: 48V Off grid system for down payment on 6 Acres help

chevenstein wrote: »

Gww,
The 500A draw is momentary (< 1 second) then falls to about 40 when the pump is running. Note that when I had half of my battery bank (220AH @ 48V) on 6 gauge temporary wiring the voltage drop on the AC side was so bad when the pump started that most other AC loads connected would shut off when the well pump started.
Chevenstein

Have you tested it since you installed the new cables and Battery bank ??

SERESOLAR

Re: 48V Off grid system for down payment on 6 Acres help

chevenstein wrote: »

To the OP's original questions: I have a similar deep well pump that I run off grid with the system in my signature and have borrowed a fancy industrial motor troubleshooting ammeter to see that the startup load on the DC side for my pump is over 500 AMPS. My battery bank and inverter can barely start this thing even with 2/0 wire on the DC side, let alone run the well pump for an extended period of time (tens of minutes would be a stretch on fully charged batteries due in part to the Peukert effect: http://en.wikipedia.org/wiki/Peukert's_law ).

I would consider replacing the pump itself with a model that can be soft started and/or a DC model that can run directly off of the array, depending on how the well is to be used.

PS - I would not use homemade panels for cost, safety, and longevity reasons.

Buying some panels from solar blvd.com that Photowhit helped with providing they have 220W 24v panels for a good price i was thinking 4 of them,

Also got the call back from the engineer tech i emailed regarding my pumps full electical details, he says the pump needs for start up of Minimum 5000w at 230V so 21.7 or 22 amps at start up (for <1 second) for no harm to be done to the pump. And a running draw of (min)1600W-2100W (max) at 230V, 9.1 Amps (max)

so for my 48V system a starting of 104Amps <1 Sec (tech said it was literly 4/10 sec) and running at 33-45 Amps . So my Pure sine inverter i was about to return which is continuos 2800W and well enough surge over 5000W for the start up should work for me?

chevenstein

Re: 48V Off grid system for down payment on 6 Acres help

Blackcherry04 wrote: »

Have you tested it since you installed the new cables and Battery bank ??

Yes, the instantaneous peak is still >500A, but the voltage drop on the AC side is not as severe.

chevenstein

Re: 48V Off grid system for down payment on 6 Acres help

SERESOLAR wrote: »

so for my 48V system a starting of 104Amps <1 Sec (tech said it was literly 4/10 sec) and running at 33-45 Amps . So my Pure sine inverter i was about to return which is continuos 2800W and well enough surge over 5000W for the start up should work for me?

There are too many unknowns here. 104A on the AC side for 4/10 of a second probably assumes connection to grid power with correctly sized conductors, so there is virtually infinite capacity for motor starting load. In an off grid scenario you are pushing the batteries, connection from the batteries to the inverter, and the inverter itself very hard in this situation so each component must be up to the task to start this pump. The detailed specifications for your inverter should list surge ratings for different time intervals; oversizing your battery to inverter connection will minimize your potential for problems there and the batteries themselves should be sized according to the longest duration you plan to run the pump times at least two for a reasonable maximum depth of discharge.

I reiterate: you may be able to solve this problem less expensively by changing the pump.

Photowhit

Re: 48V Off grid system for down payment on 6 Acres help

SERESOLAR wrote: »

... providing they have 220W 24v panels for a good price i was thinking 4 of them,...

I don't think the site reference has any true 24v panels currently (though I'll check when I get to work) They have a nasty habit of calling panels with a VMP of 26-31 volt '24volt panels' they are NOT, and will require a mppt charge controller to work properly and you would have to have strings with a vmp of 70volts (individual panels of 35v VMP) to use pairs of panels...

SERESOLAR

Re: 48V Off grid system for down payment on 6 Acres help

chevenstein wrote: »

There are too many unknowns here. 104A on the AC side for 4/10 of a second probably assumes connection to grid power with correctly sized conductors, so there is virtually infinite capacity for motor starting load. In an off grid scenario you are pushing the batteries, connection from the batteries to the inverter, and the inverter itself very hard in this situation so each component must be up to the task to start this pump. The detailed specifications for your inverter should list surge ratings for different time intervals; oversizing your battery to inverter connection will minimize your potential for problems there and the batteries themselves should be sized according to the longest duration you plan to run the pump times at least two for a reasonable maximum depth of discharge.

I reiterate: you may be able to solve this problem less expensively by changing the pump.

thanks for reply

Unkowns?? thats straight from specs from pump company not assuming connection to grid power, the starting at safe minimum for an alternate power source is 5000W at 21amps for 230V. what the pump (wants) when on grid is 52 amps at 230V so about 12,000W for less than a second, and this pump is not running for more than an hour to fill a 200Gallon tank for Emergencies thats it , pump is 5gpm at 1Hr thats 3ooGallons so im not seeing the hard impact on the batteries when by math at 328AH can put the 45amps thats needed to the pump to last 4.2hrs at 50% which will never happen.

SERESOLAR

Re: 48V Off grid system for down payment on 6 Acres help

Photowhit wrote: »

I don't think the site reference has any true 24v panels currently

http://www.solarblvd.com/Solar-Panels-&-Systems-24-Volt-Solar-Panels/c1_270/p2712/MX-Solar-220W-24V-Solar-Panel-MX60-220/product_info.html

let me know if there not what im needing thanks

Cariboocoot

Re: 48V Off grid system for down payment on 6 Acres help

From the listed specs:

"Rated voltage Vmpp, V28.9"

Not a true 24 Volt panel which would have a Vmp of 35.

BB.

Re: 48V Off grid system for down payment on 6 Acres help

When off-gridders talk about 12/24 volt panels, they are talking about Vmp ~ 17.5-18.6 volt (35-38 volt) panels that will run efficiently with a PWM charge controller.

When GT folks talk about 24 volt panels, they are usually talking about Vmp in the range of 28-30 volts or so--Not really high enough voltage to reliably recharge a battery bank in hot weather.

-Bill

SERESOLAR

Re: 48V Off grid system for down payment on 6 Acres help

ok so i am getting a new charge controller for the one i originaly bought was for 12/24 volt systems. that was the original plan for the battery bank. i am going for a MPPT controller and was curious on if stacking two 24V MPPT controllers was a way to go and how to go about doing that. or just go with a 48V 40amp controller
thanks

-Jett

Cariboocoot

Re: 48V Off grid system for down payment on 6 Acres help

SERESOLAR wrote: »

ok so i am getting a new charge controller for the one i originaly bought was for 12/24 volt systems. that was the original plan for the battery bank. i am going for a MPPT controller and was curious on if stacking two 24V MPPT controllers was a way to go and how to go about doing that. or just go with a 48V 40amp controller
thanks

-Jett

You don't stack charge controllers to up Voltage, you just get one that can handle the system Voltage. Most of the 'top end' MPPT controllers can do 12, 24, or 48 Volts without any problem. Most have an input Voltage limit of 150 (MidNite being the exception here as they have models that can take up to 250 Volts). Input and output Voltage don't have to match (the controller will adjust), but input has to be above charging Voltage for the system.

You can stack controllers to handle greater current if necessary (usually a bad idea to need to) or charge from multiple arrays ('stationary tracking').

The main problem with the smallish battery bank is not supplying the Watt hours but rather the current surge when that pump starts. 12 kW on 24 Volts is a massive 500 Amps and may result in a momentary severe Voltage drop that stops the whole thing from working.