Thread: Solar Panel Voltage Control

I have this for my dashboard solar panel,, about 30 bucks from Jaycar

Your solar reg needs to have a battery connected to it for it to work properly. If you're measuring the regs battery output without a good battery connected the reading is meaningless. Connect a reasonably charged 12 volt battery to the regs battery connection and see what voltages you get. I'd expect an end voltage of around 14.3 volts.

With cheaper regs such as the projecta when they fail quite often it's the voltage regulation ability that fails and the higher than normal charging voltage unchecked can then stuff the battery(s).

Your reg may actually be OK.

If you're charging an important or expensive battery bank it's a good idea to use a quality reg to guard against reg failure taking out the battery(s).

Victron mentioned earlier make excellent regs as do Morningstar and no doubt others do as well.

Deano

Originally Posted by JDNSW

It is quite possible that the regulator you have will not regulate to reduce the output voltage if no current is being drawn. I suggest you connect it to a suitable load and measure the output voltage with that.

The ideal would be the battery, and keep an eye on the voltage as it charges, but a suitable resistance such as a couple of tail light bulbs in series (will stand the maximum possible voltage but low enough current draw to cause voltage regulation if working) would enable a faster assessment.

John

You may not have a problem. Your regulator could be operating normally. 17.5 volts is 4.5 amps. Even if it goes to 18 volts why is that a problem?
My 80 watt was supplied by the manufacturer with a 10 amp regulator. The panel would normally operate at less than peak power.
I actually have mine feeding into a 10 amp circuit breaker as an extra safety measure.

Originally Posted by BMKal

Any solar panel experts on here ?

I have a Projecta folding 80W solar panel kit, which includes a Projecta SC005 voltage controller / regulator. Over the past week or so, I have been using this to supply some power for electrolytic cleaning of some old cast iron cookware and an old workshop bench vice. So far, has been working well - but today I wanted to use the solar panel set-up to charge up an old "Thumper" battery that was sitting in the back of the shed.

When I checked the output voltage at the end of the leads (alligator clips) - I was getting 17.5 volts. And that was with the solar panels in the shade - when I moved them into direct sunlight, I was seeing output as high as 20 volts.
So I unplugged the SC005 voltage regulator and measured the voltage being produced directly from the solar panels (in the shade) at 18.1 volts.

From this, I assume that the Projecta voltage regulator is not worth two knobs of goat **** (I did note the "made in China" information on the face of the unit) and it will be removed tomorrow. For the purpose of continuing my electolytic cleaning processes, I have no problem with direct connecting the supply from the solar panels to the cathode & anode in my chemical bath - anything up to about 20 volts is quite OK for this purpose.

However, before I use the solar panel again to charge any batteries, I will need to install a decent regulator. I have been meaning to re-position the regulator for some time anyway, as I was advised a while back that it should be positioned as close as possible to the battery being charged to reduce voltage drop in the lines to the battery terminals - so now's as good a time as any.

Anyone have any good suggestions for a decent voltage regulator that doesn't cost the earth. Obviously, I'll be steering clear of any rubbish produced by Projecta, but there must be other reasonably priced units out there that do the job.

Because Mick if that is what voltage it's throwing into the battery post regulator (BM has to check under load) then 17v will cook the batteries.

Thanks all for the advice. I tried connecting to a battery this morning (WAECO Thumper) and was still getting ~ 20 volts when direct sunlight on the panel. However, I later discovered that this battery was dead flat (less than one volt) and would not even accept charge from my CTek charger. It is now charging OK using an el-cheapo charger that seems to be better at charging from dead flat.

So I tried connecting the solar panel up again directly to my electrolytic rust removal project - initially showing between ~ 14 and 17 volts at the tub, but after a short period, drops down to nothing at all. I assumed that this was because the voltage controller sensed insufficient load or something, and cut the power. It was pretty obvious even without using the multi meter, as the bubbling in the tub stopped.

So - have now removed the voltage controller / regulator altogether, and running directly from the solar panels to the electrolysis tub. When direct sunlight on the panels, and when I only had one anode connected (I have two steel plates, one in each of the tub), I was getting about 10 volts at the tub. If I connected the second anode to give better distribution of the electrolysis within the tub, the voltage dropped to about 8.5 and sat there pretty steady for the rest of the day (until the sun started to go down).

So, I am still not sure if the Projecta voltage controller / regulator was working correctly or not. After I have finished cleaning what I have left to do, I will connect the regulator back into the circuit (but on the "battery" end of the cables rather than on the "solar panel" end as I have been advised to do), and try it out on a decent and charged battery.

At the moment, the el-cheapo battery charger is on the Thumper (it seems to be accepting charge OK), the CTek is plugged into the back of the D4 (haven't topped up the batteries in that for a few months, so it's due, and I wanted to make sure that the CTek is still working OK after it wouldn't put any charge into the Thumper earlier today - everything looking OK with it plugged into the D4 though) - and the solar panels are plugged into what SWMBO is calling my "mystery" tub out near the shed, waiting for the sun to come up again tomorrow.

The electrolytic cleaning / rust removal has been working very well so far (apart from some issues in keeping up power supply to it. I tried doing a couple of components in apple cider vinegar for comparison - it worked but nowhere near as well as the items cleaned using electrolysis. So far, I have finished restoring an old workshop bench vice (now re-assembled, oiled and mounted on one of the benches in the shed), plus one camp oven and an old cast iron kettle, both of which were seasoned today using flax seed oil. Have been very pleased with the way everything is turning out so far ................. still a few more items to go, including one larger camp oven. I also have one huge camp oven (made from a truck rim) that I am thinking of using as a fire pit. It's way too big for anything we are likely to need in the future. The last time it was used, it had a whole goat plus vegies in it at a work Christmas party ............. and that was a few years ago. This one is definitely too big to clean using electrolysis, but is still pretty clean and well seasoned on the inside anyway.

Brian.
I would love to see some pics of your set up and the results of the 2 methods.
Andrew

I'll take a few pics tomorrow of the before, during & after.

Unfortunately, I can't show the results of the vinegar soak - it really didn't work as well as I had hoped, and I have since re-cleaned the items that I had previously soaked in vinegar for three days.

Originally Posted by Tombie

Because Mick if that is what voltage it's throwing into the battery post regulator (BM has to check under load) then 17v will cook the batteries.

That was without a battery connected to put a load on the regulator, so I thought it wouldn't prove much. Hopefully if it's put on a charged battery the regulator will pull it down.