Increasing capacity of 20A solar regulator

[tarbaby]

I have a 20 amp Plasmatronics solar regulator in our van. It manages the output from 3 X 150watt panels, so the regulator is at or a bit beyond capacity, current-wise. I want to put more panels on the van, and double the solar output to 900 watts, if I can find room on the roof among all the things that get in the way.

The way to increase capacity apparently is with a solid state relay controlled by the load circuit of the regulator, so that the switching of the regulator is mirrored by the SSR. I plan to do it as described and illustrated in the Plasmatronics downloads. I just have difficulty understanding how this works, and am concerned that I will be feeding panel voltage to the battery via the SSR. I understand that the regulator can detect battery voltage and reduce its voltage supplied in absorption and float phases (is this correct?), but how does the voltage passing from the panels through the SSR get reduced?

[Mrcoolabah1au]

Ask T1 he know everything there is to know electric and all that stuff

[tarbaby]

yes I think so, just waiting for him.
probably a nice evening in SA yes? maybe he is outside have a quiet glass of something?

[dapope]

More like working his butt off doing an install. If you are able to follow the diagram then it will all work..

[T1 Terry]

I have a 20 amp Plasmatronics solar regulator in our van. It manages the output from 3 X 150watt panels, so the regulator is at or a bit beyond capacity, current-wise. I want to put more panels on the van, and double the solar output to 900 watts, if I can find room on the roof among all the things that get in the way.

The way to increase capacity apparently is with a solid state relay controlled by the load circuit of the regulator, so that the switching of the regulator is mirrored by the SSR. I plan to do it as described and illustrated in the Plasmatronics downloads. I just have difficulty understanding how this works, and am concerned that I will be feeding panel voltage to the battery via the SSR. I understand that the regulator can detect battery voltage and reduce its voltage supplied in absorption and float phases (is this correct?), but how does the voltage passing from the panels through the SSR get reduced?

Unless you can supply more than the battery can accept the battery will hold the voltage down, if the input is greater than the battery can accept the voltage will climb until the Plasmatronics regulator control voltage is reached, then the SSR's internal mosfet turns off/on exactly the same as the mosfet in the Plasmatronics regulator does. The trick is to use the correct resistor, the correct SSR and a cooling method for the heatsink so the SSR remains below 50*C. Do not be tempted to buy the cheap SSRs sold on evilbay, they will heat up at an alarming rate wasting a lot of the solar energy harvested and virtually need to be water cooled to stop them from destroying themselves. I'm guessing they are the rejects from various manufacturers because no one in industry would tolerate such a high internal resistance.

T1 Terry

[tarbaby]

Thanks Terry, all is clear now. So the battery suppresses the voltage at the SSR input, whch slowly rises until it reaches the regulator limits, which then controls further input.

I have this obsessive compulsion to understand things. It doesnt help that my knowledge of all things electrical is fairly rudimentary and lacking in theoretical training.

I may have more questions ...

[T1 Terry]

It is the battery that holds the voltage down at the battery terminals, the SSR is letting everything flow through it till the controller says the voltage has reached its control limits, then it turns the SSR off, then the voltage drops as it is absorbed into the battery so the controller turns it back on, and the on period gets gradually shorter and the off period gradually longer, but the on/off can be multiple times a second so a mechanical relay wouldn't last very long, but an electronic relay (mosfet) can but it does waste a bit as heat when switched rapidly, this is the reason for the heatsink so this heat can be drawn away from the SSR and into the air. Too much heat and the unit dies so if a lot of current (amps) is being turned on/off rapidly the heat sink on its own can't get rid of enough heat, then a fan is needed to move the heat away faster, a poor quality SSR and even the fan can't move enough heat fast enough to keep the SSR cool.
The unit we make san hand up to 200 amps, but we try not to push them that hard for very long and generally build the system to run at 50% to 75% peak, so if we had 200 amps to control we would just use 2 units side by side. The fan is controlled by a thermostat to turn on at 50*C and off at 45*C, each SSR has its own thermostat and we assemble them in pairs on a tunnel heatsink with the fan on top. The Plasmatronics regulator can handle as many of these as required so there is no limit to just how many amps the regulator can control really, just add more SSR modules

T1 Terry

[Jon and Kay]

I now put all of the 1100watts @12v through the 100A SSR. I found my PL40 did not allow the full output of the panels due to heat compensation in the controller, so I recommend using a SSR in this way, rather than running some of the panels via PL and the others via SSR (provided cable sizing allows)
My 400ah of Lithiums reached a year old last week, consistently returning the same SOC each morning and reaching Float by midday. I can charge via Alternator, Solar or Charger (shore power or gennie) all at maximum 70ah each. We are full time on the road, never use caravan park jails, use a 7.5kg washer/dryer,a 240v fridge and a 240v freezer, split system aircon. The best thing about the LFPs is the high charge acceptance, and ability to accept high loads.

[tarbaby]

I have a Jaycar 100a SSR part no SY4086 and heatsink. I was planning on mounting the heatsink on an aluminum panel, on which is mounted a 45C thermostat controlling a small fan which pumps air from outside the van. I am not sure if these are good quality SSRs, but the current that I plan to run through them will be less than half their rated throughput, so hopefully will be OK.

I now put all of the 1100watts @12v through the 100A SSR. I found my PL40 did not allow the full output of the panels due to heat compensation in the controller, so I recommend using a SSR in this way, rather than running some of the panels via PL and the others via SSR (provided cable sizing allows)
.

I find this interesting, because I have been considering how to install a high voltage cutout in the event that I ever get around to putting in lifepo4 batteries. I read somewhere that Dingo and Pl regulators go into an error state if they are cut off from the battery while receiving solar input, so that a HVC that cuts all charge without disconnecting the solar panels will cause problems with the regulator. If, like Jon and Kay I put all the charge current through the SSR, I wont have to worry about cutting the solar feed to the regulator. Does this sound right?

[T1 Terry]

You are on the right track, drop me an email and I'll try to guide you through the mine field so you at least have the base set up ready for what ever battery chemistry you choose to run in the future.

T1 Terry