Solar Regulator

Thanks a lot. Will head off to camping show now. Great idea.

Ian

Boobook,
you say: "If you have 160W of panels, you will get a maximum of about 110W usable with PWM such as the ones suggested. You will get up to about 150W with a MPPT one. That is 40W for free"



How can 12 Amps from 200 Watts, while panels are laying *horozontal* on the roof, be explained ?

Image Could Not Be FoundMaîneÿ . . .

Thanks for the ideas.

ian

Maîneÿ,

Do you have a wiring diagram for how you have set up the Steca and the amp and volt meters?

I have always been interested in that when you post photos of your setup.

I currently have my regulator and power system built into a home made battery box, but I am intending to wire up a house battery for the van but want to keep my charging system portable for when we just take the tent and our boxed gell cells.

Thanks

Pete

Pete,
will do it shortly and email you direct :)
(have MM you with questions)

Maîneÿ . . .

Mainey said

"How can 12 Amps from 200 Watts, while panels are laying *horozontal* on the roof, be explained ? "

Mainey where is the 12 A? Is it before the reregulator or from the reg to the load or somewhere else. Also what is the panel voltage?

If the panel voltage is 14.2 ( just reading the panel voltage on the meter) then that is about 170W output.

It really is impossible to tell the panel output just from that photo. But I can tell you that if it is PWN then your average charging loss is about 30%

Boobook,
You say:
"If the panel voltage is 14.2 ( just reading the panel voltage on the meter) then that is about 170W output"

Your numbers are not relevant to the information I've posted
the relevant facts are:

The panel Voltage would be ~17+ Volts 'minimum'

Yes, I agree it's impossible for me to PROVE the panel output *from the photo*
but the Manufacturers specifications do confirm the panel *Operating Voltage* is 17.2 Volts
Image Could Not Be FoundImage Could Not Be Found

The 14.2v you quote, as shown on the voltage meter, is only the voltage measured down at the battery, this voltage is NOT relevant to Solar panel Voltage.


The 12 Amps, as displayed on the Steca LCD, is registered @ the Steca controller (see photo)


Using your own maths:
17 Volts x 12 Amps = 204 Watts

( my panels are: 123 Watts + 80 Watts = 203 Watts, is this just coincidencial ? )

Maîneÿ . . .

Mainey it's not your panel that is inefficient, it is your regulator. A PWM.

14.2V (output) x 12 A is about 170 watts. Please read the previous posts.

Yes the MPPT regs give better efficiency, but for the price I can buy another two panels and leave them mounted on the 4BY and then who cares about efficiency then! ;o)

I guess the bottom line is that both Maîneÿ and I have systems that work for us. I can go on an extended stay, run my Waeco, charge the laptop and camera and have lighting at night all from 70 AH of gell cells and 100W of panels. Maîneÿ's setup is better than mine so he should have no problems at all.

If it has been cloudy or my campsite is shady I might run my batteries down a little, but I can always take the fridge and batteries for a spin in the Jack when we are looking at the local area if I get desperate. Sometimes I take a genny along if I know in advance that these conditions will be an issue, but not often.

Cheers

Pete

Boobook2 posted:
"Mainey it's not your panel that is inefficient, it is your regulator.
14.2V (output) x 12 A is about 170 watts. Please read the previous posts"

Ok, lets go back to Maths class :)

The only FACTS we are positive of are:-> 12 Amps and 203 Watts

Do you agree with the numbers so far ?

203 Watts / 12 Amps = 16.91 Volts

this is not NOT your 14.2 Volts

My point is how can the regulator be "inefficient" when it can deliver 12 Amps from a 203 Watt Solar system that's been sitting up there since god knows when and only gets cleaned when it rains :)

This picture clearly shows the 10 Amp gauge is past it's limit and the charging Voltage is 13.7v both pictures were taken on different days, this one was at 9.50am Image Could Not Be FoundMaîneÿ . . .

Mainey where did you get the 16.91 V? I took 14.2v from your voltmeter in the photo.
Just to be clear.

Yes the panel can output 200W in the right conditions ( at it's maximum power point). No Question. BUT this is at 18 ish volts, not usable to a battery. It is thte role of the regulator to drop the voltage to that of the battery requirement.

The power delivered to the battery is the voltage at the (battery & Load) x the charge current to them.

The power at the panel is the voltage at the panel x the current.

The difference in these is a loss.

Boobook2,
You ask: "Mainey where did you get the 16.91v? I took 14.2v from your voltmeter in the photo just to be clear "

The 14.2 Volts is only the *charging* Voltage of the AGM's, nothing else, nothing to do with Voltage produced by the Solar system, which as Sharp claim in their technical info is 17.2 Volts.

# Voltage meter under the Steca regulator shows my AGM's Voltage
# Ampere meter shows the Amps going either 'in' 0R 'out' of the AGM's

These two gauges take into account current used by the fridge and all accessories and give a constant readout of their relevant numbers, they are not reliant on the Steca for any information.

You ask: "where did I get the 16.9v"
You also say: "The power at the panel is the voltage at the panel x the current"

power = 203 Watts
current = 12 Amps
voltage = 16.9 Volts

The maths are as follows:
203 divided by 12 = 16.9v

The Solar system is *203* Watts and capable of producing at least *12* Amps (shown in picture)

( Sharp tech info states 17.2v but I use a 123W Sharp and a 80W Solarex (BP) panel which obviously compromise results )

You also say: "Yes the panel can output 200W in the right conditions. BUT this is at 18 ish volts. It is the role of the regulator to drop the voltage to that of the battery requirement"

YES, absolutely and totally correct :)
that's why it's showing 14.2 Volts in the Volt meter picture above
as I've been attempting to show you, it's NOT the Solar panel Voltage, but as you say it's the BATTERY Voltage.

But where this is in any way relevant to your thoughts that the Steca reg is inefficient is beyond me :)

To get 12 Amps from a 203 Watt Solar system is realistic
The only 100 Watt system I can find for direct comparison purposes is the GP100W
power: 100 Watt
current: 5.8 Amp ( 2 systems = 11.6 Amp )

Maîneÿ . . .

So unless I am missing something Mainey we agree.

Your Panels appear to be putting out 200W as claimed by the manufacturer.

However losses in your regulator mean that there is only 14.2V x 12A = 170W available for charging. A loss of 30W in your regulator or about 15%. It would be a 50W approx loss if the battery was only half full.

On the other hand a MPPT charger would charge the 14.2 v battery at 14A ( 200W less a few percent.)


Try it yourself Mainey.

Get that battery ( which would be at about 12.3V), and put your solar panels in the sun on a good day and pointing right at the sun.

Measure the voltage on the batteries, measure the current into them with no other loads and multiply them together. V x I = P in watts. Bingo, about 170 Watts. The rest being lost in your regulator as inefficiencies in the system.

Do it again woth 50% discharged batteries and the power will be more like 150W. A loss of 50W in your regulator.

A MPPT charger would charge that battery at about 15.5A with the same 200W panels. Ie a loss of only about 6watts.

Simple maths.

Oops
"Get that battery ( which would be at about 12.3V)"
should read

"Get that battery ( which would be at about 12.8V at rest or 14.2v under charge)"

Boobook,
We disagree :)
so lets see if I can say it more clearly from a different perspective ?

You say:
" losses in your regulator mean that there is only *14.2* Volt x 12 Amp = 170 Watt available for charging. A loss of 30W in your regulator or about 15%."

Your maths are not relevant because 14.2v is only the *regulated* Voltage
it's definitely NOT the Voltage produced by the Solar system ( ~17 Volts )
It's the Voltage *after* it's been regulated = the battery charging Voltage


Some irrefutable facts are:

Sharp panel is rated @ 7.16 Amps
Solarex panel rated @ 4.71 Amps

Manufacturers total Amps: 11.87
This is a fact beyond dispute :)

As can clearly be seen there is definitely *no Amp loss* at the Steca regulator

To be even a 10% loss the Steca would have to show only ~10.7 Amps MAX

Maîneÿ . . .

Mainey. I never said there was an amperage loss. Look at what I posted. In fact I even calculated the power los using 12A in each case. What I said was there is a POWER loss of 30W.

I am sorry but it is pointless arguing this with you any more. You clearly have no understanding of the fundamentals of electric power unfortunately.

I'm not arguing with you at all, you say whatever you want, it's obvious that when a Solar system is rated at a certain number and also charges at the same number there is no loss.

Remember you posted a Steca is only 70% efficient in charging / delivering loads

The numbers clearly show this in not correct, they are efficient.

Maîneÿ . . .

Hi,

i now see why others hate solar questions...too much talk and not enough listening lol

For the record, your explanation boobook makes sense to me....as someone who is trying to get their head around solar regulators. Thanks for the clear explanation of power calculations and losses.

If ANYONE believes that there is NO losses in any tranformation of power then they are kidding themselves:

"it's obvious that when a Solar system is rated at a certain number and also charges at the same number there is no loss."

Andrew

Andrew,
You say the "explanation boobook makes sense" to you..

Then you explain how 12 Amps can be only 70% efficient from the output of a 203 Watt Solar system ?

Maîneÿ . . .

Mainey, read follow up 7 of 18. It explains everything. Calculate the POWER you are delivering to the battery.

Forget the 200W from the panel. That is correct, but it is delivering 12A at 17.2v, but your battery is only 14.2 according to your meters.

Therefore (17.2-14.2)Volts x 12 Amps of POWER is lost in your regulator.

That is a 36WATT loss in your regulator. Not magic.

Hi Mainey Your system looks to me too work just fine in reality world. So i wouldnt get too boged down with the numbers boys.

Mainey, I refer you to the link that Ed C posted below. It explains it better than I can and in simple terms. Hopefully this will make sense to you.


Ed posted

Perhaps this may assist >>

MPPT solar charge controllers

;-))

Geez Mainey you're still going. Got to give you points for perseverence ;)
Power in vs power out equals % performance, and there's no such thing as a perpetual motion machine.
Devices consume power.
Didn't we go through this a few years back?

Boobok's figures are correct, and if anything a bit forgiving, as he uses the manufacturer's specs for full output rather than an empirical measurement. Due to manufacturer's specs being at optimal conditions (as opposed to real -world conditions) the loss is probably less than will really occur.
But there must be a loss.

People seem to think that these "12V threads" are full of differing opinions, and this isn't the case.
This is simple physics/chemistry and to each definitive question there will be one correct answer only.

It's always had me buggered why self-taught fellows will argue with people who are professionally trained. Sometimes I wish Ohm's Law was proscribed reading.




ed

Thylacine,
My 203 watt Solar system is rated @ 11.9 Amps (manufacturers figures)
My system clearly shows 12.0 Amps @ the Steca regulator

Will you please answer these 2 easy questions with a ONE WORD reply ?

Questions:
(1) is there any loss shown in *Amps* to the battery in the 12 Amp picture ?
(2) what is the loss ( % ) with 12 Amps, as is shown in the 12 Amp picture ?

Maîneÿ . . .

Mainey, I am sorry but you just don't get it do you? Unfortunately your last question further demonstrates your lack of understanding. For the 1 millionth time, current is preserved, it is POWER we are talking about.

Did you read the article?

Arrrrrgh. Ok you got me, now I really do give up on you.

If you can ONLY think in amps going into the battery, with the same sunlight and panels, then look at it this way.

A conventional PWM Regulator puts 12 amps into the battery.

An MPPT regulator puts 14 amps into the battery.

The conventional PWM regulator is less efficient COMPARED WITH the MPPT Regulator.

An MPPT Regulator can put MORE current into the battery than the current rating of the solar panels. HOW it does this is obviously a waste of time.

This entire long line of followUps is ONLY based on the following post by Boobook:
"This compares to about 70% for PWM regs"

Read my posts and you can clearly see I have not claimed PWM regs are as efficient as the MPPT system, because they use different technology.

It is ONLY relevant to Boobooks statement the Steca is 70% efficient

My question remains unanswered, how can it be only 70% efficient if the same Amps produced by the Solar system are ALSO sent to the battery, as my pictures clearly show this is the case, I don't believe the picture is *****.

Maîneÿ . . .

Mainey
I find it interesting that none of your pictures show the charging current display.
Image Could Not Be Found

Only the solar modules output current display.

Image Could Not Be Found

Since this is a shunt regulator, then the module output current is
being diverted through the internal shunt except for the 5 amp going to the battery.
By your meters the charging power is currently 71.5 watts. (5 amps X 13.3 volts.)

The 12 amp solar panel output is at an unspecified voltage as it is internal to the regulator and is related to the short circuit current of the solar cells.

I suggest you show us some pictures of the charging current display if you want to show us the efficiency of your solar system. I think the pictures you display only show us what you want to see, not the real conditions.

Lex,
the reason is the picture showing the "12 Amps on the Steca LCD" was taken on 21-11-07 @ 11.21am, the other pic (13.7v @ Steca LCD and the Amp meter below showing >10 Amps going into AGM's) was taken on 5-10-07 @ 9.50am and are stored on my computer hard drive.
Sorry but I can only show pictures I have.

Are you suggesting the picture showing 12 Amps @ the steca and also the 5 Amps @ the Amp gauge below it, in the same picture, is not realistic ?

Maîneÿ . . .

The picture is a picture which tells us nothing about the efficiency of the regulator.

It shows the output current of the solar panel at an unspecified voltage, most probably the short circuit current. Not the charge current.

It shows a battery at a good state of charge at which the regulator has determined a 5 amp input current is appropriate.

It shows you are getting 71.5 watts of effective charge.(5 amps X 13.3 volts.)

It shows that the regulator is shunting up to 7 amps of solar panel current. (12 amps - 5 amps.)

The regulator is doing exactly what you want. It's charging the battery.

The solar panel is providing more than enough power for the required charge. more than half of it's capability is being wasted.

If you want to show the efficiency of the regulator, show us a picture of a battery in a state of charge that can absorb the full output of the solar panel.
Then show us the CHARGE current as measured by the regulator and the meters.

You have to understand Mainey that a solar panel with its output shorted can produce lots of amps but (almost) no power. Similarly when its not connected it can produce lots of volts but no power. The useful operating point is somewhere between those two extremes. Volts go up and amps come down dependant on the load connected. The power output is the product of volts and amps for the load conditions at the time.

To get a realistic picture of the efficiency you have to record all the parameters at the same time and analyse the results.

"This entire long line of followUps is ONLY based on the following post by Boobook:
"This compares to about 70% for PWM regs"

Read my posts and you can clearly see I have not claimed PWM regs are as efficient as the MPPT system, because they use different technology.

It is ONLY relevant to Boobooks statement the Steca is 70% efficient

My question remains unanswered, how can it be only 70% efficient if the same Amps produced by the Solar system are ALSO sent to the battery, as my pictures clearly show this is the case, I don't believe the picture is *****.

Maîneÿ . . . "

It's 70% efficient in terms of the POWER produced by the Solar Panel and the POWER going into the battery.

The Solar Panel could be putting a lot more CURRENT and POWER into the battery by using all of the VOLTAGE that Solar Panel can deliver - but only when using an MPPT Controller which delivers more CURRENT into the battery than the CURRENT that is coming out of the Solar Panel.

Mike
I'm going up North this week as it's cool and wet here now, so will get pictures requested

My point is the 203 Watt solar system develops ~12 Amps (manufacturers figures) and the Steca shows 12 Amps available, it's not the picture you asked for, so will get new ones, the (10a) Amp gauge shown below the Steca shows >10 Amps is going into the battery simultaneously

Maîneÿ . . .