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Forum Index : Solar : Build a Mppt 3 Kw Charge Controller
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| Ghost Newbie  Joined: 30/03/2019 Location: NigeriaPosts: 25 |
140a, what a current 🤕. |
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| azhaque Senior Member  Joined: 21/02/2017 Location: PakistanPosts: 117 |
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| Ghost Newbie Joined: 30/03/2019 Location: NigeriaPosts: 25 |
Hello Mike, I suffered pic microchip freezing at higher current above 30a with my previous mppt before I then isolate the pic gnd and buck gnd, now everything is stable, but isolation is way cost, I want to ask you "adding tvs diodes across PV input, will it limit the EMi generated by the Inductor ?" I use only 470uf at the PV input . |
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LadyN Guru  Joined: 26/01/2019 Location: United StatesPosts: 408 |
Do all these run on 48V? I have two 1kW arrays and I have kept them at 106V nominal each. That keeps the current at 9A I wish I could parallel them but I have repeatedly failed to do so. I can power almost all home units (laptop, TV, lights, modified oven so it runs on 230v) without an inverter (straight 230v DC) using this. For surge currentABILITY I will need either a large cap bank (in progress) or grid share (not an option for you BUT I'm working on it too) Is 230V that not an option for you? PS: Even with this, I will have to learn and implement load sharing between these two arrays and the grid because the voltages change too much and I want to use diode OR config. if possible. Let me know if you want a separate thread to brainstorm this |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Two ways to tackle a problem like this. 1/ Go to a higher system voltage, 100v dc @75 amps, or 200v dc @ 38 amps would be far more practical. 2/ Run the inverter direct from the solar panels, and use the solar controller only for charging the battery. Cheers, Tony. |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Yes careful design needed to prevent ground loop interference, opto-couplers work well here. No, TVS diodes across the pv input will have no effect on EMI; you will require a ferrite cored choke with suppression caps to stop your panels acting as an antenna for generated EMI. Cheers Mike |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
I agree, that's why we are going to 150 - 180 vdc pv array input voltage for the three mppt controllers used on the 50v lead carbon bank. We could move the storage bank voltage to 100v, but gets more problematic getting standard off the shelf components to run at the higher voltages and more hazardous, we are using a lot of DC solenoids\pumps etc for controlling water flow running direct off the bank supply. |
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| azhaque Senior Member Joined: 21/02/2017 Location: PakistanPosts: 117 |
No, 230 VAC. The inverter that powers these devices is on 48 VDC. For redundancy I have a second inverter running at 24VDC that powers the lighting fans wall sockets etc. It is run off a 2.5K solar array. I have 4 arrays, two each of 2.5K nominal and 2 more of 3.5K nominal. Previously these were just two, 5K and 7K, based on similar panels. However I have had to reconfigure them to 4 exactly for the reason that you have mentioned. It isn't right now because I am using commercial CCs that have a 96 VDC upper limit. I am waiting for SolarMike to finalize his 200 VDC MPPT CC which I will then deploy in place of my current PWM units. I need to parallel the CC outputs to increase current capacity. I don't think direct paralleling of arrays is possible except by having an intervening electronic system. SolarMike was talking about a multi-phase unit for the future so that system expansion can be easily managed. I am not sure this concept has been studied or not for the domestic market. I am sure that it would be available for the commercial (solar power generation for the grid) market. Maybe this can be studied in this forum. azhaque |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
I am definitely interested! Do you have a link to the post where you saw this? Also, in this thread I make this observation: |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
Why the difficulty in paralleling them? LV arrays have been paralleled for decades without issue (A blast from the past, my first offgrid place was 3kw, at 24v, using 2 100w 12v panels in series, then the lot paralleled , using copper waterpipe as busbars (flattened out by driving a truck over them!) Electronics that could handle that kind of power was way out of my reach at the time, so it had a rather crude 'macguyver' reg system- it just poured the power into the batteries (a uteload of ex telstra exchange batteries) which usually took it without too much hassle, but if the voltage rose dangerously high, a voltage sense circuit made from a modified 24v truck generator regulator literally pulled a pin out of a knife switch with a solenoid (said switch shamelessly 'borrowed' from the railways) which had a lead weight hanging off it- and with a rather impressive spark it would shut off- telltale was a piece of fishing line run into the house that pulled a indicator flag from a signal box (also borrowed from the railways) into the red 'tripped' position Things have changed, just a bit... |
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| brucedownunder2 Guru Joined: 14/09/2005 Location: AustraliaPosts: 1548 |
Hey Good morning Boppa, What a beaut story, a real BACKSHED type yarn.... I can just imagine it.. Luv the water pipe bit, she's a real story out of the Ol Foottrot Flats comic book -Youse young guys don't know that comic book ,a dinky-di Aussie comic book. I digress, sorry. A good story, Bruce Bushboy |
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| BrianD Newbie Joined: 06/05/2014 Location: New ZealandPosts: 7 |
Hi Brucedownunder2 Footrot flats comics were written by Murray Ball and he wasn't an Aussie |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Quite correct there Boppa, paralleling isnt generally an issue, however if the charge controller say has an upper safe charge current of 60 amps, and we add additional PV to the system that could allow that 60a to be exceeded; that is the problem. If the array can supply 100 amps charge current and the controller can only handle say 60, then it must current limit in a very fast manner to prevent damage at the buck switching rate. The current transducer generally outputs an averaged current not a peak pulse value depending on the device used. I could use a fast transducer and alter the PWM value on a cycle by cycle basis to prevent overload, or do as currently and average (slower) combined with huge overload capability in the switching devices. If you look at the spec's of most controllers they have a max PV input power capability and the cheaper ones would probably blow up if exceeded, ie they cannot current limit. Cheers Mike |
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| Boppa Guru Joined: 08/11/2016 Location: AustraliaPosts: 814 |
Ahha, sorry, I was reading it as the arrays weren't outputting full output power when paralleled unless each array had its own controller, which didn't make sense to me (I had just driven 600km, which may have been a factor LOL) (I had every Footrot Flats cartoon book when I was a kid lol- Didn't hear about it at the time, but he died in 2017) :-( |
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| BenandAmber Guru Joined: 16/02/2019 Location: United StatesPosts: 961 |
I can't wait to this controller is finished I'm betting it's going to be one of the best ones in the world be warned i am good parrot but Dumber than a box of rocks |
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| LadyN Guru Joined: 26/01/2019 Location: United StatesPosts: 408 |
Yes, this is the power board and I'm really hoping Mike ends up using an ARDUINO platform like the STM32 or the ESP32 for the brains. I understand Mike wants to put in battery charging algorithms in here but with an ARDUINO codebase, the MPPT bit could be used to make a MPPT inverter instead that could power share with rectified grid. The ESP32 excites me because it specifically has I2S, ULP, RMT and the like that makes this a wonderful controller to use. It has two regular cores and of course the above ultra low power (ULP) third core. Because of the built in BT or WiFi, it allows one to run an asynchronous webserver on it that will allow one to remotely monitor what the mainprocessor sees. The control program runs on the other core. When the sun goes down, it can shut down the two regular cores to reduce power needs and use the third ultra low power (ULP)core to see if it should come up. If we can go this route, except the PCB and the capacitors, the BOM cost could very well be $50 or less! $50 for a 3kW MPPT Buck convertor! Mike will know better of course. |
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| azhaque Senior Member Joined: 21/02/2017 Location: PakistanPosts: 117 |
Mike, I have been looking at the circuit from the point of view of implementation once the circuit design is finalized. One of the local issues in Pakistan is availability of components. So I always view any project from component availability perspective. The ZXGD3005E6 that you have used to increase gate current/charge capacity is likewise not available locally. So I have been researching a replacement for this component. The datasheet for the 3005E6 does not give the internal block diagram of the chip. However the datasheet of the 3009DY shows a simple two transistor totem pole arrangement. So I am assuming that the 3006 wouldn't be much different. So my question is whether I should look at the possibility of using discrete transistors as a replacement for the 3005. |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
Strange, that chip is pretty much available at nearly all the large suppliers (RS, Element14 DigiKey etc) at approx 50c each, all over the world. No you cannot use discrete transistors without complete re-design of the pcb. Cheers Mike |
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| Solar Mike Guru Joined: 08/02/2015 Location: New ZealandPosts: 1138 |
I have ordered a couple of STM32 boards to play with, by profession I'm a dot net programmer, so it will be a bit of a learning experience to move to another platform.... Used to higher level object orientated languages. Mike |
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| Ghost Newbie Joined: 30/03/2019 Location: NigeriaPosts: 25 |
Hello Mike, can I use 1 piece of irfp4568 (180a silicon limited) to switch PV input in a 45a mppt , typically maximize PV current is 28a to 30a . And what about 2*irfb4115 (to220 130a silicon limited) . Please which is better recommended ? |
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