Living offgrid with small solar system(s)

[George Harmony]

Sorry mod. My internet connection was slow ive pressed several times the send button ??

[Muhendis]

Sorry mod. My internet connection was slow ive pressed several times the send button ??

George. This one was covered ages ago. Startup current can be anything from 5x to 9x normal running current. Starting under load will be the higher number (or more) the length of time for the startup is dependant on the mass of the pump armature and the load. Water does not compress so the load will be all of the mass of water in the pipes which has to start moving less slippage of the pump impeller. So a 1 HP pump is 746 watts which will quite happily draw 3.24 Amps when running plus a bit more for efficiency losses. Startup current at 230 volts will be between 16 Amps and 29.2 Amps for anything from a few hundred milliseconds to a second or more. The motor current will diminish to the normal running current as the motor picks up speed. The reason for this is that the back EMF normally generated by the revolving armature is not there when the armature is stationary so all you've got at the instant of switch on is the dc resistance of the coil in the motor. Variations on this startup depend on whether the motor is switched on at the zero crossing point of the voltage cycle or the peak of the voltage cycle. This is not a problem with brushless dc motors, but if you're intending to run an ac motor then make sure your inverter has the spare capacity for motor starting on load when other loads may also be drawing current.

[George Harmony]

I got the price to change from my generator and 1 HP submersible pump. The complete solar system and DC pump would cost 124,000 baht. That choked me up some. I can buy a lot of gasoline for that much money. The fruit trees my wife waters are not worth that much. I have to hope for rain to refill my pond.

This with inverter and accessoires excl panels=44.000bht.

4x250wp panels=4x7000=28000bht.

Above prices r rounded prices but real.

Why pay double??

[Naam]

announced power cut today lasted exactly 10 hours (08.20-18.20).

temperature house main area ~22.5ºC when power went off and ~28ºC @ 18.20 hrs.

load on main battery bank was ~1,300 watts.

initial voltage under load 25.8 when power was cut, voltage after 09h45m 24.3.

any comments from the learned resident sparkies?

[Gary A]

I got the price to change from my generator and 1 HP submersible pump. The complete solar system and DC pump would cost 124,000 baht. That choked me up some. I can buy a lot of gasoline for that much money. The fruit trees my wife waters are not worth that much. I have to hope for rain to refill my pond.

This with inverter and accessoires excl panels=44.000bht.

4x250wp panels=4x7000=28000bht.

Above prices r rounded prices but real.

Why pay double??

Because it is a high quality Lorentz system. All sorts of safety sensors and water level protections.

[Gary A]

announced power cut today lasted exactly 10 hours (08.20-18.20).

temperature house main area ~22.5ºC when power went off and ~28ºC @ 18.20 hrs.

load on main battery bank was ~1,300 watts.

initial voltage under load 25.8 when power was cut, voltage after 09h45m 24.3.

any comments from the learned resident sparkies?

Not bad, your batteries will live for a few more outages.

[Gary A]

I got a price for batteries. One 200 AH 2 volt tubular AGM type battery is 18,000 baht. Of course you need six for 12 volts. That comes to 108,000 baht plus shipping.

[Naam]

I got a price for batteries. One 200 AH 2 volt tubular AGM type battery is 18,000 baht. Of course you need six for 12 volts. That comes to 108,000 baht plus shipping.

not too much compared with the cost of an aircraft carrier.

[Naam]

announced power cut today lasted exactly 10 hours (08.20-18.20).

temperature house main area ~22.5ºC when power went off and ~28ºC @ 18.20 hrs.

load on main battery bank was ~1,300 watts.

initial voltage under load 25.8 when power was cut, voltage after 09h45m 24.3.

any comments from the learned resident sparkies?

Not bad, your batteries will live for a few more outages.

we experience these long outages only once or twice a year.

[Gary A]

It appears that your backup systems are sized quite well.

[Naam]

announced power cut today lasted exactly 10 hours (08.20-18.20).

temperature house main area ~22.5ºC when power went off and ~28ºC @ 18.20 hrs.

load on main battery bank was ~1,300 watts.

initial voltage under load 25.8 when power was cut, voltage after 09h45m 24.3.

any comments from the learned resident sparkies?

charging time till the "normal" 27.1V reached was 4hours 15 minutes (probably a little less).

question for the learned: "can one extrapolate percentage of drawn down amp hours using charging time (built-in charger variable output but max 15amps)?"

Edited April 27, 2016 by Naam

[Muhendis]

announced power cut today lasted exactly 10 hours (08.20-18.20).

temperature house main area ~22.5ºC when power went off and ~28ºC @ 18.20 hrs.

load on main battery bank was ~1,300 watts.

initial voltage under load 25.8 when power was cut, voltage after 09h45m 24.3.

any comments from the learned resident sparkies?

charging time till the "normal" 27.1V reached was 4hours 15 minutes (probably a little less).

question for the learned: "can one extrapolate percentage of drawn down amp hours using charging time (built-in charger variable output but max 15amps)?"

There are far too many variables to give a definitive answer to your question Naam.

If you had a known constant load across your batteries during your outage then it is a fairly straight forward case of converting that into amp hours. Trouble is, I expect your load varied considerably during your 10 hours. Your best bet if you want to know these things is to fit a bidirectional amp hour meter (http://www.ebay.com/itm/DC-120V-100A-Voltage-Current-AH-Meter-Battery-Charge-Discharge-Bidirectional-/170483294165) to your battery so that you can record the amp hours in and out again.

[Naam]

There are far too many variables to give a definitive answer to your question Naam.

If you had a known constant load across your batteries during your outage then it is a fairly straight forward case of converting that into amp hours. Trouble is, I expect your load varied considerably during your 10 hours. Your best bet if you want to know these things is to fit a bidirectional amp hour meter (http://www.ebay.com/itm/DC-120V-100A-Voltage-Current-AH-Meter-Battery-Charge-Discharge-Bidirectional-/170483294165) to your battery so that you can record the amp hours in and out again.

load did not vary!

hiw are the six leads connected?

[Crossy]

One of several options, the charger goes between the + of the battery and the cold (non-battery) end of the shunt.

[Muhendis]

You say the load did not vary which helps. Is the load supplied direct from the batteries or is there an inverter involved. If there is an inverter any losses would need to be taken into consideration and added to the output load. If you have no idea about inverter losses then you can still work out the A/h consumption but it won't be so accurate.

Load power divided by the applied voltage will give the result in amps. Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

Thanks to Crossy for the drawing. The device is simply a volt meter that is used to measure the voltage drop across a very very low value resistor (the shunt). The circuit and display is powered by your battery with facility for an external supply if needed which in your case it isn't. Current from the battery goes through the load and the shunt and calculates all the magnificent information which will keep you happy for hours.

Edited April 27, 2016 by Muhendis

[Naam]

Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

your doubts are justified! a thorough load recalculation came up with just 920 watts ±5%, initial applied voltage was 25.8 = 35.7 amps.

battery bank consists of four 12V/120Ah. is it correct to deduct 357Ah from the total nominal 480Ah and arrive at a remaining ~25% theoretical capacity?

what i still don't understand is that it took only 4h15m to recharge

Edited April 27, 2016 by Naam

[IMHO]

Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

your doubts are justified! a thorough load recalculation came up with just 920 watts ±5%, initial applied voltage was 25.8 = 35.7 amps.

battery bank consists of four 12V/120Ah. is it correct to deduct 357Ah from the total nominal 480Ah and arrive at a remaining ~25% theoretical capacity?

what i still don't understand is that it took only 4h15m to recharge

Not really, because your bank is only 480Ah if it's discharged over a 20 hour period (standard lead acid ratings are based on how much current it takes to deplete the cells to 20% charge over 20 hours). Discharging over a shorter period than 20 hours (or in your case, faster than 24A) significantly drops the total capacity.

Edited April 27, 2016 by IMHO

[George Harmony]

A Thai video of someone who operates a pump directly from a small array of 2 panels.

Did he indeed run the pump directly from the panels??? It seems that the pump is a strong pump.

If its all true, can anyone read thai?? They were some reactions. Cause im very interested in such a pump

if this demonstration is not a hoax.

[Naam]

Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

your doubts are justified! a thorough load recalculation came up with just 920 watts ±5%, initial applied voltage was 25.8 = 35.7 amps.

battery bank consists of four 12V/120Ah. is it correct to deduct 357Ah from the total nominal 480Ah and arrive at a remaining ~25% theoretical capacity?

what i still don't understand is that it took only 4h15m to recharge

Not really, because your bank is only 480Ah if it's discharged over a 20 hour period (standard lead acid ratings are based on how much current it takes to deplete the cells to 20% charge over 20 hours). Discharging over a shorter period than 20 hours (or in your case, faster than 24A) significantly drops the total capacity.

it seems i got a lot to learn but my questions are not answered. however, the only important thing is that i have enough power storage for 10 (most probably 12-14 hours) for all communications including a 70" TV which consumes ~320 watts.

any power cut exceeding 12 hours and i'll be on my way to a hotel

[Jing Joe]

One of several options, the charger goes between the + of the battery and the cold (non-battery) end of the shunt.

Great graphics there Crossy. How did you do that? But my goodness the current is flowing the wrong way. Is it like cyclones/hurricanes that go the other way North of the equator?

Seriously though, has conventional current from pos to neg become popular again after 100 years or so?

[Jing Joe]

Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

your doubts are justified! a thorough load recalculation came up with just 920 watts ±5%, initial applied voltage was 25.8 = 35.7 amps.

battery bank consists of four 12V/120Ah. is it correct to deduct 357Ah from the total nominal 480Ah and arrive at a remaining ~25% theoretical capacity?

what i still don't understand is that it took only 4h15m to recharge

Not really, because your bank is only 480Ah if it's discharged over a 20 hour period (standard lead acid ratings are based on how much current it takes to deplete the cells to 20% charge over 20 hours). Discharging over a shorter period than 20 hours (or in your case, faster than 24A) significantly drops the total capacity.

it seems i got a lot to learn but my questions are not answered. however, the only important thing is that i have enough power storage for 10 (most probably 12-14 hours) for all communications including a 70" TV which consumes ~320 watts.

any power cut exceeding 12 hours and i'll be on my way to a hotel

Naam; 320 Watts, that's a lot of power for a LED TV or is it plasma? But then again that's a BIG TV and I reckon Plasma un-popularity now might not stretch to that size anyhow. Just out of curiosity what brand/model please so I can keep up with the latest? Happy with the definition? Edited April 27, 2016 by Jing Joe

[Muhendis]

Your load is 1300 Watts and your applied voltage is 28.5 Volts. That's a whopping 45.6 Amps. I'm having problems with that much current for 10 hours. What is the size of your battery bank?

your doubts are justified! a thorough load recalculation came up with just 920 watts ±5%, initial applied voltage was 25.8 = 35.7 amps.

battery bank consists of four 12V/120Ah. is it correct to deduct 357Ah from the total nominal 480Ah and arrive at a remaining ~25% theoretical capacity?

what i still don't understand is that it took only 4h15m to recharge

Not really, because your bank is only 480Ah if it's discharged over a 20 hour period (standard lead acid ratings are based on how much current it takes to deplete the cells to 20% charge over 20 hours). Discharging over a shorter period than 20 hours (or in your case, faster than 24A) significantly drops the total capacity.

it seems i got a lot to learn but my questions are not answered. however, the only important thing is that i have enough power storage for 10 (most probably 12-14 hours) for all communications including a 70" TV which consumes ~320 watts.

any power cut exceeding 12 hours and i'll be on my way to a hotel

It is my considered opinion that the calculated load of 1.3kW or 930 Watts (whichever) is not the true load I suspect the aircon spent quite a lot of time not running having achieved the target target temperature. You need to get one of those amp hour meters to see what is really happening or maybe connect your computer to the inverter to do a bit of data logging if that's possible.

[Muhendis]

A Thai video of someone who operates a pump directly from a small array of 2 panels.

Did he indeed run the pump directly from the panels??? It seems that the pump is a strong pump.

If its all true, can anyone read thai?? They were some reactions. Cause im very interested in such a pump

if this demonstration is not a hoax.

I am quite sure that is not a hoax. The measured current is quite normal for solar. The motor looks to be a high speed dc motor of some sort. The power is really great but we only see the free flowing water maybe it would not be so good trying to drive that through a pool filter.

[Muhendis]

One of several options, the charger goes between the + of the battery and the cold (non-battery) end of the shunt.

Great graphics there Crossy. How did you do that? But my goodness the current is flowing the wrong way. Is it like cyclones/hurricanes that go the other way North of the equator?

Seriously though, has conventional current from pos to neg become popular again after 100 years or so?

Jingjoe There is a problem with the current flow indication. The device is bidirectional so the arrows should be pointing in all directions........

[Jing Joe]

If I were going to go totally solar, I would definitely set up a ground mount system. Orientation would be precise and cleaning the panels would be easy. At this point my panels on the roof look like they haven't been cleaned for years. It's unbelievable how dirty they get. I'm getting about half of the rated wattage. Fortunately that's enough power for my requirements even on overcast days. I doubt that my system will ever pay for itself but there is the satisfaction of having clean power free from spikes and low voltage. The best part is there are never power outages.

Maybe the question is why don't I clean them? The answer is that at 71 years old, I don't want to be standing on the roof, cracking tiles and risking injury or death. When I ask my 100 pound light weight wife to clean them, she just gives me that, "Are you crazy" look. And no, just spraying water on them doesn't work.

@Gary A; With our age and wives unwilling to do rooftop housework we have a lot in common. Yes amazing how the dust sticks o panels even with the slope involved here at latitude 27 degrees. Ground based orientation will be to your advantage and how about simple tracking system too? Not in common is the roof with obviously more slope hence the tiles. Mine is nearly flat but I did make a permanent safe ladder system too.

Whats your latitude? I feel for George located right on the equator and logically having dead flat panels??

Edited April 27, 2016 by Jing Joe

[Naam]

It is my considered opinion that the calculated load of 1.3kW or 930 Watts (whichever) is not the true load I suspect the aircon spent quite a lot of time not running having achieved the target target temperature. You need to get one of those amp hour meters to see what is really happening or maybe connect your computer to the inverter to do a bit of data logging if that's possible.

are you joking? none of my systems can power an aircon!

breakdown of the load:

1 TV 70"

1 PC with 3 monitors

1 PC with 1 monitor

1 pair of active speakers

1 transformer 220>110V for these speakers

2 satellite receivers

1 audio system (amplifier only)

1 media player

3 modem/routers

2 desk lamps

i could have reduced the load as i don't watch TV and use my PC at the same time. but i wanted to test the worst load case scenario.

[Naam]

Naam; 320 Watts, that's a lot of power for a LED TV or is it plasma? But then again that's a BIG TV and I reckon Plasma un-popularity now might not stretch to that size anyhow. Just out of curiosity what brand/model please so I can keep up with the latest? Happy with the definition?

Sony LED not plasma.

yes, happy with the definition but was also happy with my 9 year old Samsung 67" back-lit which had a built-in processor that extrapolated non existing pixels and added them.

Edited April 27, 2016 by Naam

[Jing Joe]

One of several options, the charger goes between the + of the battery and the cold (non-battery) end of the shunt.

Great graphics there Crossy. How did you do that? But my goodness the current is flowing the wrong way. Is it like cyclones/hurricanes that go the other way North of the equator?

Seriously though, has conventional current from pos to neg become popular again after 100 years or so?

Jingjoe There is a problem with the current flow indication. The device is bidirectional so the arrows should be pointing in all directions........

Thanks M there's more to it than meets the eye, I took a too-quick sleepy look sorry, and I reckon you know your stuff anyway.

You didnt say anything about the graphics/art programme?

[George Harmony]

I was thinking of replacing my tiny pump with such a pump and using my tiny pumps for hydroponics later. Ofcourse not for my planned pool. Eh, perhaps as extra for a waterfall to the pool... Would be great if i can realise it later.

Never power outage when living offgrid and never have to think of booking a ticket or hotel due to power outage @naam hehehe

300+watts for a tv???? Hmmmm..... Perhaps time to look for another

Edited April 27, 2016 by George Harmony

[Naam]

I was thinking of replacing my tiny pump with such a pump and using my tiny pumps for hydroponics later. Ofcourse not for my planned pool. Eh, perhaps as extrq for a waterfall to the pool... Would be great if i can realise it later.

Never power outage when living offgrid and never have to think of booking a ticket or hotel due to power outage @naam hehehe

300+watts for a tv???? Hmmmm..... Perhaps time to look for another

because you like sweating like a pig 24 hours a day whereas i prefer airconditioning and a lot of ice cubes in my drinks hehehe

shall i heed your advice, throw my one year old TV (129,000 Baht) in the garbage and buy a smaller one for 99,000 Baht to save 50 or perhaps 100 watts?

is it perhaps time for you to switch from cheap home brew booze to water or fruit juice? because that would eliminate some of your "intelligent" advice.