Solar regulator question

Submitted: Monday, Feb 11, 2019 at 15:24
ThreadID: 137792 Views:1006 Replies:5 FollowUps:20
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G'day everybody and hope you're all well and comfy. Don't know where else to ask such a question so please help. I've recently got into the solar thing for camping and my vehickles. Ive hooked up the solar regulator to charge my AGM battery and run the fridge by connecting it to the battery directly. Now I notice that the solar regulator has a load outlet on it (solar panel-Battery charge-Load). Should I be running my fridge off the load connection on the regulator or is it the same as connected direct to the battery? Regards Boris
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Reply By: Peter_n_Margaret - Monday, Feb 11, 2019 at 15:38

Monday, Feb 11, 2019 at 15:38
Some solar regulators keep a record of power in and power out. To do that they need to be able to measure the loads and the LOAD terminal is one way to do that.

Many load terminals have fairly low capacity though, so they are limited. The specs of the controller should tell you its capacity.

What type of fridge is it? If it is a gas/12V fridge, the load is probably too high for the controller. If it is a compressor fridge it is probably OK
.
It is not much use though to measure the fridge power consumption if you are not measuring all of the other 12V loads as well...
Cheers,
Peter
OKA196 motorhome
AnswerID: 623767

Follow Up By: Boris K - Monday, Feb 11, 2019 at 16:22

Monday, Feb 11, 2019 at 16:22
Thank you for your reply. Just for everyones info, the solar regs are very simple 20amp Sun Yee specials, the two fridges I run are an old waeco 35 or a Verb 60 waeco. The two AGM batteries I have are 130amp hour each. Two solar panels are 200w and a 160 mounted permanently to the car. Ive been running the 35 waeco direct to the battery for about a year now and the battery hasnt really needed a charge with the 200w panel but wondering if it is beneficial to run the other way.
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Reply By: RMD - Monday, Feb 11, 2019 at 15:47

Monday, Feb 11, 2019 at 15:47
G"day Boris
Some regulators have that port to switch on or off, to a settable time. Not much use for fridge though. Others may cut off the power to the load when battery drops below a certain lower threshold. Not sure if yours has those features.
Some instructions with regs are in Chinglish and hard to work out the logic or actual meaning of printed words.

I have a few different regs and can't understand how to set it, if settable.

For most of the time it is the same as connecting fridge to battery, which I prefer, because it is one less Mosfet swtiching transistor less in the frdige circuit.
If the fridge flattens the battery too low, then the charging ability is then the question. I have never used that port anyway.
Usually you need quite a bit more solar panel output than first thought of, particularly if the fridge is used in hotter climates or used as a freezer at any time.
AnswerID: 623768

Follow Up By: terryt - Monday, Feb 11, 2019 at 15:55

Monday, Feb 11, 2019 at 15:55
So do those replies mean you can draw power via the load connection on the regulator when there is no input. ie at night
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Follow Up By: Boris K - Monday, Feb 11, 2019 at 16:12

Monday, Feb 11, 2019 at 16:12
Good Question Terry
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Follow Up By: Peter_n_Margaret - Monday, Feb 11, 2019 at 16:51

Monday, Feb 11, 2019 at 16:51
"So do those replies mean you can draw power via the load connection on the regulator when there is no input. ie at night"

Yes.

Cheers,
Peter
OKA196 motorhome
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Follow Up By: terryt - Monday, Feb 11, 2019 at 17:24

Monday, Feb 11, 2019 at 17:24
Thanks Peter. For some reason I have always thought the load output was only good when the panels were working.
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Follow Up By: Peter_n_Margaret - Monday, Feb 11, 2019 at 18:24

Monday, Feb 11, 2019 at 18:24
I have an old (14 years) PWM Plasmatronics controller. It has a good "information" display capability including total power in and total power out for each day and uses that to calculate SOC.
The load terminal is good for about 14A (from memory - many are much lower). I run the 2 compressor fridges and all the lights from that. The other general loads I run via a 50A shunt and a 200A shunt for the inverter loads and charge loads from the alternator. Both shunts report to the controller so it knows what went in and what came out of the batteries.
Cheers,
Peter
OKA196 motorhome
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Reply By: RMD - Monday, Feb 11, 2019 at 17:57

Monday, Feb 11, 2019 at 17:57
Boris
I see you have now revealed it isn't one battery but two, and you have what sounds like two regulators too and also two solar panels.
Are the panels in parallel or separate and each has it's own regulator?
If two panels, are the batteries also in parallel, ie.charged as one, or separate and effectively you have two solar systems with a fridge on each?
You have to know the specs and what each regulator is made to do before connecting to the load terminals if that is your choice.

If people know the situation they can reply more accurately to your situation.
for example.
If you suddenly decided to run both fridges from one LOAD port, typically 10amp max, it may tax the regulator load output quite a bit. Especially if they start at the same time when cycling. What is the load rating?


Two solar panels 200w and a 160w in parallel into one 20 amp reg, would be asking it to work hard to dump charge into discharged batteries. If it is a PWM regulator then it's switching devices will run hot when solar is in full sun, batteries down a bit and near max current if being metered in. MPPT reg a different story.
AnswerID: 623775

Follow Up By: Boris K - Monday, Feb 11, 2019 at 18:22

Monday, Feb 11, 2019 at 18:22
They are all set up on different (2) vehicles separately mate with only one spare panel for the camp ground. All fridges are set up to run direct from the battery. Ill be getting a 30amp regulator and piggy back wiring so I can run two panels to one battery if needed once I see how I go at Blanket Bay in March. And I just moticed that you mention theres a difference in regulators between MPPT and PWM. I didnt know that. I think theses are PWM.
Regards
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Follow Up By: Boris K - Monday, Feb 11, 2019 at 18:52

Monday, Feb 11, 2019 at 18:52
I haven’t used the solar panels in a camp scenario yet. We haven’t camped in 6 or more years.
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Follow Up By: RMD - Monday, Feb 11, 2019 at 20:00

Monday, Feb 11, 2019 at 20:00
Boris
The more efficient regulators are MPPT, “maximum power point tracking”. Sounds fancy doesn’t it, however, an mppt regulator makes more deficient use of the available power from the panel. Instead of dumping the panel energy into the battery and holding the panel voltage to near the battery voltage while switched on, the mppt unit uses inverter technology to hold the panel at a higher voltage and more energy is therefore usable and transferred for the battery charging.
These regs are more expensive as a result. Some brands only use an mppt function while they are in bulk charge mode and return to pulse width modulation while in absorption and float mode.
Best to research these if interested in using that type.

Be aware, many cheap eBay MPPT regulators are not MPPT at all and are falsely represented. Check the specs closely. Others will know/use reputable brands.
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Follow Up By: Boris K - Monday, Feb 11, 2019 at 20:11

Monday, Feb 11, 2019 at 20:11
I will look into it thank you but can you recommend a 30amp one that doesnt break the bank?
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Reply By: Frank P (NSW) - Monday, Feb 11, 2019 at 22:17

Monday, Feb 11, 2019 at 22:17
When camped I run my fridge off the LOAD terminals on the solar regulator. That way the panels power the fridge and left-over power in excess of what the fridge requires goes to charging the battery. If the sun doesn't shine adequately the fridge is powered by the battery, which it would be anyway if connected direct to the battery.

This way if you have sufficient solar wattage and sufficient sun the battery has no load on it, which I believe is a better situation for the charging part of the regulator - ie it cannot be confused by fluctuating battery voltages as the fridge cycles on and off.

Re your question to RMD about recommendations for a reasonable 30 amp MPPT reg that won't break the bank, you could have a look at this one from Jaycar. A number of folk in our large Karavan club have used it with success.

Cheers
AnswerID: 623780

Follow Up By: Boris K - Tuesday, Feb 12, 2019 at 08:05

Tuesday, Feb 12, 2019 at 08:05
Thank you for your reply Frank. What you wrote makes sense to me and I will give it a go. I like the caravanners recommendations too as I had a caravanners recommendation here regarding a smart charger from Jaycar that is still working brilliantly 15 years later. But, one more question, which way is best to connect 2x200w panels for use with a MPPT regulator? Since yesterday Ive started reading all the forums on this and it is very complicated. REgards
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Follow Up By: Frank P (NSW) - Tuesday, Feb 12, 2019 at 10:22

Tuesday, Feb 12, 2019 at 10:22
Boris,
We need to know a bit more information for a complete answer, but in general you can connect two panels either in parallel or in series. Both have advantages and disadvantages. I think it's fair to say that the most practical method in a portable panel or camping scenario is parallel.

If you choose the Jaycar regulator I linked to, then your two panels connected together will be 40 watts over the max specified for that reg for a 12 volt system, which I presume yours is. I think you'd get away with that as the reg should dump excess input that it cannot process. I would have to check on that.
In any case it would occur only in ideal conditions, which are infrequent.

Can you look at the labels on the back of the panels and advise what the numbers are for Voc, Vmp and Imp. Voc or open circuit voltage is probably the most important for this discussion.

Cheers

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Follow Up By: Boris K - Tuesday, Feb 12, 2019 at 10:48

Tuesday, Feb 12, 2019 at 10:48
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Follow Up By: RMD - Tuesday, Feb 12, 2019 at 11:18

Tuesday, Feb 12, 2019 at 11:18
Frank P
Are you sure the load runs from the panels before the regulator?
If it did, the voltage to the load terminal would be fluctuating at the PWM frequency and therefore, changing from around 0.6 above battery voltage to near the 22v which is open circuit of the panel. A constant regulator cause change of close to 10v sometimes. Not sure fridges would like that sudden over voltage fed to their electronic circuits.
I have an Ecoworthy MPPT regulator and it has a section which can be set to turn load on and off at programmed times. Some others turn off load at set times after solar/sun is not happening. I think the battery is connected to the load terminals for load use, but the regulator wouldn't be supplying the load first and then the battery.
Because the MPPT part is effectively an inverter, there is no direct connection from panel to load terminal at all under MPPT mode. PWM is used for absorb and float. I imagine very similar situation in a PWM regulator too. ALL regulators and or chargers in vans or battery chargers simply change their output amp and voltage to siut the battery condition. If a fridge is present and running it simply adjusts to it. An alternator is a vehicle does the same. A DC/DC charger does too.
I cannot see any advantage in running a fridge off the load. Happy to discover otherwise.
Thousands of people have solar, reg and battery with fridge running off a direct to battery as Boris has, they all work properly.
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Follow Up By: Frank P (NSW) - Wednesday, Feb 13, 2019 at 15:07

Wednesday, Feb 13, 2019 at 15:07
RMD
It is my understanding based on what I was told (or thought I was told) by the manufacturer of my MPPT regulator. It's a GSL MPPT 30-2. However your discussion is persuasive and I checked again today. The advice was that basically the output of the regulator is shared between the load on the LOAD terminals and the battery. I'm trying to get my head around the difference (if there is one) in effect between that and my previous understanding.

Perhaps it's a subject for its own thread rather than hijack this one.

Boris,
Those panels will be fine in a parallel setup with the Jaycar regulator I linked to. Be aware there are plenty of other brands you could look at, some cheaper some more expensive, but in researching for other people I and they have found this one to be a good performer at a reasonable price.

Right or wrong, I've had perfect results with the fridge connected to the LOAD terminals on the regulator, but as RMD said, thousands (ie, most people) connect the fridge direct to the battery.

In the PDF I've shown a parallel setup. I prefer to use blocking diodes in the output from larger panels like yours to stop backfeed from a lit panel to a shaded or partially shaded one. Again, most people don't bother with this, but I do and it's cheap. Eg, Diodes. You can leave them out if you wish.




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Follow Up By: Boris K - Thursday, Feb 14, 2019 at 01:48

Thursday, Feb 14, 2019 at 01:48
Thank you for all your help. Ill be getting a MPPT from Jaycar soon
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Reply By: Allan B (Sunshine Coast) - Wednesday, Feb 13, 2019 at 16:15

Wednesday, Feb 13, 2019 at 16:15
.
Boris, you sure have some information above to digest.

The simple answer to your question..... "Should I be running my fridge off the load connection on the regulator or is it the same as connected direct to the battery?"..... is 'probably not' or maybe even 'no'.
And no, it is not "the same as connected direct to the battery".

The primary function of the 'Load' connection is to disconnect the load when the battery voltage falls below a set value in order to prevent over-discharge. This value will vary by model and will probably be in the range of 10 to 12 volts.
The 'Load' connection will have a limited current capability, again varying by model, and will possibly be less than what you may wish to draw. So then it would be preferable to connect your loads directly to the battery. Independent over-discharge protection of adequate current capacity can be arranged if desired.

Some models of solar charge controllers have additional functions associated with the 'Load' function. Typical are settings to switch the load on & off to programmable times, intended for controlled lighting. Also, on more featured controllers, the 'Load' connection may monitor the discharge current to determine the state of battery charge.

For solar charging of recreational vehicle charging, my recommendation is to not use the 'Load' terminals at all.

Cheers
Allan

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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Feb 13, 2019 at 16:30

Wednesday, Feb 13, 2019 at 16:30
.
Boris, further to the above, I have looked up the specs of your Sun Yee controller and it states.......
Discharge stop: 10.7V(default, adjustable)
Discharge reconnect: 12.6V(default, adjustable)
Discharge Current: 20A

Pretty much as I expected.
Cheers
Allan

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Follow Up By: RMD - Wednesday, Feb 13, 2019 at 17:41

Wednesday, Feb 13, 2019 at 17:41
Thanks Allan,
I regard the use of LOAD much the same. I didn't like the load you rely on for a fridge, to be through a MOSFET all the time. Yes it is fed from the battery terminal point which has it's origin from the regulation, be it MPPT or PWM.
I have had a couple apart and the load runs off the same BUS bar as the battery terminals do.
If any short circuit happened in the line and the instantaneous current flow talked harshly to the LOAD Mosfet then it may fall over.
Then people would be forced to use the battery connection. I see LOAD as a weak link for an essential fridge supply. All is OK while all is OK though, perhaps.
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Follow Up By: Allan B (Sunshine Coast) - Wednesday, Feb 13, 2019 at 17:55

Wednesday, Feb 13, 2019 at 17:55
.
Yep RMD, with respect but perhaps stated more explicitly...........

..."the load runs VIA THE MOSFET off the same bus bar as the battery terminals do".

Before someone tells us that the "Load terminal is NOT connected to the battery bus".

Cheers
Allan

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Follow Up By: bellony - Thursday, Feb 14, 2019 at 00:34

Thursday, Feb 14, 2019 at 00:34
I don't imagine Boris is very interested in the fact he may have a MOSFET in his controller.
Boris, your fridge probably (Waeco, Engel etc do) has a low voltage cutout to save the battery voltage from going too low. If this is the case leave it how it is and enjoy the camping.
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