No power from panels to mppt?


New Member
No power? to mppt from 4 in series group 100 w HQST panels. No power at mppt which is hooked to 200ah sok battery. Checked all connections. followed diagram in Wil’s book. How do I troubleshoot the problem. I’m feeling bad on this one.


New Member
I’m digging up a volt meter. Battery just came in the mail. I guess I can’t do any without a meter. I’ll check back when I test the volts.


Solar Addict
Are you exceeding max input volts?

Good question (one reason I asked for the voltage reading). He said they are 100w panels, so most MPPT controllers "should" handle it.

Not sure if he is getting no power or just a little, because the battery may already be full which would explain low power. He also said he just got the battery today, so I hope it was connected (and connected first).


Solar Addict
Found a multi meter I’m confused I’m getting 34 volts on a evening sky. What’s going on?
Your HQST panels have some performance numbers on the back. If you wired 4 panels in Series, then the voltage on the wire ends (before connecting into the MPPT Solar Controller should be very near 4 times the V(oc) of a single panel., even under moderately strong sun (without shade). There are many possible problems here.... including (most disastrous) the possibility of 4 times V(oc) exceeding the maximum PV Voltage of your MMPT Solar Controller. Example: If you had 4 panels with V(oc) of 22.0 Volts each, wired in Series to make 88 Volts V(oc), and you plugged that into a "60 Volts maximium" MPPT controller, then you will have fried the MPPT controller. A 36 Volt reading is possible near sundown, very late in the day.

First, tell us the specifications (and preferably the model number) of that MPPT controller. Also whether the SOK battery is "12v" or "24v". Before plugging in the "PV" solar leads, check your PV Voltage on the 4 panels in fairly bright sun. Also check your battery voltage as recently received by you.

Before plugging in those PV solar leads (tape them carefully before you plug them into the MPPT controller; 85-95 Volts is a bit dangerous to mess with). You can plug in your battery(s) to the Solar Controller, but you should then re-program your MPPT charging parameters for charging an LFP battery string (at either "12v" or "24v" nominal). There are many Threads and Posts with advice about setting those charging parameters - search is your friend for that topic.

If your battery is already nearly "full", (e.g., more than "float" charging Voltage on your MPPT), then it might not accept very much power from the Solar array. But your MMPT display should still show the Solar with high Voltage (around V(mp) when charging heavily, or around V(oc) when hardly charging at all), and it should show "battery voltage" at the same value you have measured with the meter.

The only way to "force" your MPPT controller and Solar Array to deliver a lot of power into the batteries is to put a big load on the battery (bigger than the capability of your MPPT in conjuction with that panel array and that amount of sunlight), causing the battery voltage to fall below the value for MPPT's "Boost Resume Voltage". When the battery Voltage has fallen below that value (IIRC, I have my MPPT set at 13.2V), then the MPPT is free to again supply maximum power into the battery(s) and the new "big load" at "Boost Voltage".

That will be either the maximum power of the Solar Array (minus conversion loss of roughly 4-5%), or the maximum output current capability of the MPPT controller operating at Boost Voltage -whichever is lower.

Bud Martin

Photon Sorcerer
Show us good clear pictures of your wiring/setup.
What is the make and model of the SCC?
What is the PV panel spec?


New Member
More details would help.

Did you connect the battery first, then the panels?
What model charge controller?
What makes you think it is not working?
Yes connected the battery first 8 ga marine tined copper 1 foot run from Epever 40 amp mppt. 12/24v auto working max 150v regulator tracer Bn series neg. ground control/. HQST 100 solar panel mod. HSP 100 DL. No inverter 12 v distrablution system has no fuses so. Not drawing


Solar Addict
What is the battery voltage?
As mentioned, if it is fully charged, the SCC won't have anything to do.
Does the controller have a display? If so, does it show the solar panels being connected (when in the sun)?


New Member
Here it is. I don’t know what’s going on. 4 100w hqst mono panels. Wired exactly to Prowse’s book page 62. 8ft run with 10g wire to Epever 40w mppt. 1 foot run of 8g marine tin clad copper wire to sko 200ah battery. Via bolt on 50amp fuse on pos. Battery post. Here are my readings. From panels to mppt terminals 32.7 v, battery at mppt 36.5 v
volts at battery terminals 13.5 v. Between 50 amp fuse and battery negative termina 12.6 v.
reset button on mppt dose nothing. Digital display from mppt nothing.
what next?


Solar Addict
From panels to mppt terminals 32.7 v, battery at mppt 36.5 v

Are you saying the voltage at the battery terminals of the controller is 36.5v and the battery voltage is 13.5v? If so, it sounds like something is open (fuse perhaps) between the controller terminals and the battery. The controller will need to sense the battery voltage to work.

Disconnect the panels and only connect the battery. Then measure the voltage at the battery terminals of the charge controller. Make sure you are connecting to the correct terminals. If you don't see 13.5v at the battery terminals, something is open in your wiring.
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Solar Addict
I don't understand how you can have "battery at MPPT 36.5V" with "volts at battery terminals 13.5V". They're simply connected together with BIG wire, and therefore MUST be at the same Voltage.

You should not have 0.9V voltage drop at the fuse, either. That fuse, or its terminal wiring, is defective. You either need to re-connect the wires , or you need to get a fuse which works.

You have possibly fried the MPPT by connecting something backwards, but please try doing all connections over again:

First: Connect battery "-" to the Tracer-BN "Batt -" terminal.
Second: Connect the Battery Temp Sensor, if you have one.
Third: Connect battery "+" to the Tracer-BN "Bat +" terminal.

Now plug in the MT-50 monitor/programmer unit. It should display battery voltage correctly (within a couple tenths of your meter on the battery terminals, with zero PV power and zero current to the battery. If you DON'T have those readings, don't even bother to attempt programming (it's dead).

If you DO have those good readings, then it's time to program the Tracer-BN from MT-50, using "user" battery settings. (They are similar to "Gel", but not exactly the same. They are different from "Sealed Lead Acid" in an important way - there must never be an attempt to equalize.)


Solar Addict
When the Battery versus Tracer-BN voltage difference is resolved, start programming a "user" battery profile with something like this:

Over Voltage Disconnect 14.7 V
Charging Limit Voltage 14.6 V
Over Voltage Reconnect 14.6 V
Equalize Charging Voltage - shut off or 14.4 V (with 0 duration 'equalization time')
Boost Charging Voltage 14.4 V
Float Charging Voltage 13.6 V
Boost Reconnect 13.1 V
Low Voltage Reconnect 11.3
Under Voltage Warning Reconnect Voltage 11.5
Under Voltage Warning 11.5
Low Voltage Disconnect 11.0
Discharging Limit Voltage 11.0 (irrelevant, if you do not use the SCC "load" port).
Equalize Duration 0
Boost Duration 180 minutes

After programming, you CHECK (with a voltmeter) the PV "ground" is equal to Battery "Ground". The plug the "PV -" cable to the Tracer-BN.

Finally, again check your fuse wiring along the "PV + lead", and then check the PV Voltage (versus any grounding terminal screw on the Tracer-BN). If the panels are all in Series, you should have about 80 volts. If the panels wired 2x2, you should have around 40 volts. You STILL haven't told us how you wired the panels, and references to a page in Will's book (which I don't own) don't tell me.

But one way or another, you should "see" either ~ 20 Volts (all Parallel, definitely the WRONG way to wire for an MPPT controller), or ~ 40 Volts 2x2, only useful when shading might occur), or ~80 volts (optimal for that MPPT with all-sunny conditions).

Only then plug in the "PV +" wire into the Tracer-BN "PV +" terminal. Then the MT-50 should show some charging current into the batteries at 13.6 volts.
If that all worked and you want to test for maximum PV power, you need to put a *BIG* load on that battery - somewhat more than the maximum output of the PV panels, so that the battery Voltage will be dragged *lower* than 13.1 Volts "Boost Return". The Tracer-BN should then shift charging Voltage to a higher value (up to 14.4V), putting in all the power it can get from the Solar Array.

If everything works right, you're finally done.


New Member
Well folks everything was put together the way it should be. Took another look at everything thinking my 69 year old brain was going. And low and behold saw that the fuse that bolts onto the battery post was at an angle. Fixed that hooked it all up and now am charging the battery all be it slow as it is raining. sometimes it’s the tiniest things that get us all ape.
thank you all


Solar Addict
Fixed that hooked it all up and now am charging the battery all be it slow as it is raining. sometimes it’s the tiniest things that get us all ape.
Glad you got it working. As mentioned a few times, even if the sun was out, a full or nearly full battery will show little current going into it, The only way to fully check your panel output is to load the battery more than the panel ratings.

Bud Martin

Photon Sorcerer
Good to see that you found the cause of the issue, that is why providing good clear pictures is important since we are thousands of miles away and trying to troubleshooting the problem remotely is not easy since we do not have the setup in front of us to look at.