Solarexploits Posted March 18, 2022 Share Posted March 18, 2022 Hi, I'm a newbie to solar (DIY) & have bought 10 x 310W panels & 4 x 12V 170Ah solar deep discharge batteries, all second hand (batteries are 2021, so still pretty much as new). I already have an MCS installed grid tied 4kW array which went in right back at the early tariffs & that also runs a Solic immersion controller which diverts excess power to the immersion heater instead of sending it back to the grid, I'm getting free hot water around 8 months of the year & a reduction in gas usage all year round from this I still have to get 4 of the SH panels up on the roof, but already have had it all working for a couple of months. The intention was to be able to go partially off grid, I currently have all lighting & the computer & a few other small draws all running off the panels/batteries. As I'm on the Octopus GO tariff, I get 5p a unit power for 4 hours overnight so I have a large 12/24V ROHR battery charger to top the batteries up overnight if necessary I'm running thge system at 24v so risk of electreocution is low & able to handle stuff myself, the panels are on 2 separate arrays, 4 on one & 2 on the other, running a "Giant of Sun" cheapy controller on the 2 x panels, which claims to be both PMW & MPPT - my understanding here is limited, but surely it can't be both? & a generic MPPT controller on the 4 panels (no brand name). The 4 panels are in parallel & the 2 panels are in parallel which gives correct voltage for the controllers. & the 2 controllers are in parallel charging the batteries. The batteries run a 3kW (max, 6kW peak) Gober inverter, which was a fairly cheap Chinese (I think) jobby, buit seems to generally work well so far - long term reliability may not of course be so good! Couple of questions, when the panels are in full sun & working well I'm getting charging at around 28.5V, which should be fine looking at the input spec on the inverter, but when charging this well, some of my LED lights in the house flicker, presumably being caused by the inverter, tho' it's still showing 220 - 230V output - I believe both of the controllers are adjustable to output at lower voltage, tho' not played with this as yet, is that likely to stop the flicker on the led's? or any other ideas as to what could cause this? Secondly, at present, I can only monitor battery voltages & charge amps etc. by physically going & looking at the installation, readily accessible, but still a pain. Is there a reasonably priced monitoring system which would send bluetooth signal to my phone to monitor &, better still, is there anything which would trip a relay to bring the battery charger in if voltages drop below a certain point, if we had particularly crap weather for several days for instance Any ideas/info welcome, like I said, I'm new to all this & getting on the learning curve Link to comment Share on other sites More sharing options...
SteamyTea Posted March 18, 2022 Share Posted March 18, 2022 41 minutes ago, Solarexploits said: Couple of questions, when the panels are in full sun & working well I'm getting charging at around 28.5V, which should be fine looking at the input spec on the inverter, but when charging this well, some of my LED lights in the house flicker, presumably being caused by the inverter, Does the inverter have a minimum current draw? And is it a good quality, full sine wave inverter? Link to comment Share on other sites More sharing options...
Solarexploits Posted March 18, 2022 Author Share Posted March 18, 2022 I don't recall a minimum current draw being mentioned in the specs, but it has the computer & a couple of other minor draws, maybe 100W consistent, as much as 200W if we have a lot of lighting on, I'm just slightly concerned that as I add more panels & get them properly positioned, then the input to the batteries is only going to go up. Obviously I can add other circuits which will create a bigger draw - all very experimental at present. Regards to quality, it's not one of the ghastly ridiculously cheap ones ( I played with a cheap 12V unit that was dreadful), it claims to be full sine wave & was around £160 IIRC - the make is Gober, which I'd never heard of? Link to comment Share on other sites More sharing options...
Radian Posted March 18, 2022 Share Posted March 18, 2022 Hi @Solarexploits At least you've got a 24V system! Expecting kW from a 12V inverter is crazy. I only got one hit on a 'GOBER' inverter and that was in a listing for the equipment on a yacht so can't find any real details. Have you got any photos of it? Link to comment Share on other sites More sharing options...
TonyT Posted March 18, 2022 Share Posted March 18, 2022 Try Victron they have inverters/chargers/charge controller/ apps. Link to comment Share on other sites More sharing options...
Solarexploits Posted March 18, 2022 Author Share Posted March 18, 2022 1 hour ago, TonyT said: Try Victron they have inverters/chargers/charge controller/ apps. I seem to remember Victron are far from cheap? Like I said in the title, not looking to spend fortunes, the concept is to save money on energy, rather than donate it to other sources! 😄 Link to comment Share on other sites More sharing options...
Radian Posted March 18, 2022 Share Posted March 18, 2022 5 hours ago, Solarexploits said: Couple of questions, when the panels are in full sun & working well I'm getting charging at around 28.5V, which should be fine looking at the input spec on the inverter, but when charging this well, some of my LED lights in the house flicker, presumably being caused by the inverter, tho' it's still showing 220 - 230V output - I believe both of the controllers are adjustable to output at lower voltage, tho' not played with this as yet, is that likely to stop the flicker on the led's? or any other ideas as to what could cause this? There's a great deal of variation from one LED to the next. Decent ones have regulated drivers so will reject 'noise' on the supply and give consistent lighting but the more 'bargain basement' varieties use unsophisticated capacitive droppers and these tend to exaggerate noisy AC rather than hide it. If the inverter is putting out something other than a pure sine-wave, then cheap LED's will almost certainly have a problem. 6 hours ago, Solarexploits said: Secondly, at present, I can only monitor battery voltages & charge amps etc. by physically going & looking at the installation, readily accessible, but still a pain. Is there a reasonably priced monitoring system which would send bluetooth signal to my phone to monitor &, better still, is there anything which would trip a relay to bring the battery charger in if voltages drop below a certain point, if we had particularly crap weather for several days for instance The Victron Battery Monitor is about the only off-the-shelf product I know of that matches what you're after. £190 is a bit steep I'll agree. How familiar are you with the Raspberry Pi? For £30 you could probably piece together a battery monitor using a 4 channel power monitor or a Hall Effect Current Sensor if you need more current. You could also add a relay board and get it to switch on a charger - the sky's the limit if you can scribble some code! Link to comment Share on other sites More sharing options...
RobLe Posted March 18, 2022 Share Posted March 18, 2022 MPPT = maximum power point tracking, PWM = pulse width modulation. Yes, you can have both - and I would expect any decent PV-> battery system to use both techniques. Be aware that super cheap ebay jobbies claim MPPT, but are not. I'd expect the batt controller to cope with up to some current of panels - don't fit more, a cheap thing may just overheat and die, and make sure the Vmax of the string is ok for the controller too, or the magic smoke will come out for that reason too. I'd put fuses on the batts - It sounds like 12V+12V in parallel with 12V +12V - I'd use 2 fuses, one for each 12+12 series pair, close to the battery terminal. Don't chance shorting those batteries out, it would be horrible. A 3kW inverter will want to draw up to 120A from the batteries, but don't rate the fuses that way; they are there to protect the cable, so should be lower than the cable can cope with to the inverter. How do you distribute the inverter AC power, is it all regular mains plugs and sockets ? Just because it's not mains, it will have plenty of current and probably no RCD, so take care. Link to comment Share on other sites More sharing options...
J1mbo Posted March 18, 2022 Share Posted March 18, 2022 I would suggest getting yourself a copy of this publication: https://shop.theiet.org/code-of-practice-for-electrical-energy-storage-systems-2nd-edition Link to comment Share on other sites More sharing options...
Solarexploits Posted March 21, 2022 Author Share Posted March 21, 2022 "Don't chance shorting those batteries out, it would be horrible. A 3kW inverter will want to draw up to 120A from the batteries, but don't rate the fuses that way; they are there to protect the cable, so should be lower than the cable can cope with to the inverter. How do you distribute the inverter AC power, is it all regular mains plugs and sockets ? Just because it's not mains, it will have plenty of current and probably no RCD, so take care" Good call, I will add fuses to the battery installation, it could save a fire & save the batteries! The inverter AC power has 2 paths currebtly, one is effectively an extension lead which runs the computer & modem/router, the other goes to an RCD adjacent to the consumer unit which has circuits removed from the consumer unit, lights, alarm & a couple of other small draws, connected to it, so I believe is correctly protected Link to comment Share on other sites More sharing options...
Solarexploits Posted March 21, 2022 Author Share Posted March 21, 2022 "There's a great deal of variation from one LED to the next." - Yeah, I did wonder if it was a case of the LED's reacting badly as it only seems to be 2 particular lights that are doing this, I'll try some other LED's, I was more concerned that it might be an indicator of another, underlying, problem, I don't want to burn the inverter out! If it was likely to simply be an issue of the suppy voltage from the batteries, being around the manufacturer's ceiling I think I can adjust that down on the controllers "The Victron Battery Monitor is about the only off-the-shelf product I know of that matches what you're after. £190 is a bit steep I'll agree. How familiar are you with the Raspberry Pi? For £30 you could probably piece together a battery monitor using a 4 channel power monitor or a Hall Effect Current Sensor if you need more current. You could also add a relay board and get it to switch on a charger - the sky's the limit if you can scribble some code!" - Really don't want to spend £190 just to save walking outside & lifting the lid on the box! - kinda counter productive when the aim is to reduce costs, I also wasn't sure if Victron stuff only worked with other Victronstuff, rather than any other. I had wondered about Pi/Arduino, but know virtually nothing about them, tho' I did learn code back in the days of Fortran, so have a basic understading, just no idea how to apply it in the medern world! Can anyone recommend a good learning source for Pi or Arduino, online tutorials etc? Link to comment Share on other sites More sharing options...
SteamyTea Posted March 21, 2022 Share Posted March 21, 2022 11 minutes ago, Solarexploits said: Can anyone recommend a good learning source for Pi or Arduino, online tutorials etc Just Google it. https://stackoverflow.com/ is very useful for Python coding, but in typical 'up their own arse' manner that Asperger's programmers have. https://www.instructables.com/ has useful stuff. https://openenergymonitor.org/ has some good stuff as well. 2 Link to comment Share on other sites More sharing options...
SBMS Posted March 21, 2022 Share Posted March 21, 2022 1 hour ago, SteamyTea said: Just Google it. https://stackoverflow.com/ is very useful for Python coding, but in typical 'up their own arse' manner that Asperger's programmers have. Raspberry Pi runs Raspbian OS which is Debian based so you can install any programming language you wish. Arduino's run C++ which isn't the easiest language to learn from scratch. Personally, if you're starting out coding having never done it before, I would learn something like Java to get the fundamentals of an object-oriented programming language. You can then write Java on your Pi, or learn Kotlin, or something more widely useful and applicable like javascript. All these languages are supported on Pi. Link to comment Share on other sites More sharing options...
ProDave Posted March 21, 2022 Share Posted March 21, 2022 What I like about Arduino is there is no OS to learn. You load the programming software, write some code, send it to the Arduino and it works. I had done plenty of C programming before so coding was easy. If it's your first time using a Pi and you are not famillar with Linux then that's another learning curve to climb before you even start coding anything. But they are very different beasts, it all depends what you want to do. the Arduino suited the simple program for my PV dump controller. Link to comment Share on other sites More sharing options...
SteamyTea Posted March 21, 2022 Share Posted March 21, 2022 21 minutes ago, SBMS said: learn Kotlin Seems dead easy, not. https://www.willowtreeapps.com/craft/raspberry-pi-gpio-with-kotlin-native Link to comment Share on other sites More sharing options...
SBMS Posted March 21, 2022 Share Posted March 21, 2022 19 minutes ago, SteamyTea said: Seems dead easy, not. https://www.willowtreeapps.com/craft/raspberry-pi-gpio-with-kotlin-native The main bit in here is setting up WiringPi, which provides native interaction with GPIO on raspberry PIs. This bit isn't actually language specific, so the same steps would need to be taken to set it up with other languages. Most languages though have pre-built wrappers so these steps aren't needed. As Kotlin is built on top of the Java Virtual Machine, one of its advantages is it has interoperability with all java libraries. Someone has done the heavy lifting of pre-building WiringPi into a java-compliant library here: https://github.com/soonuse/jwiringpi so you can just import that to interact with the GPIO. There are also pre-built bindings for nodejs (https://github.com/soarez/node-wiring-pi) and most other languages if you search github for WiringPi (there's some for ruby if that's your language of choice). Link to comment Share on other sites More sharing options...
Solarexploits Posted March 22, 2022 Author Share Posted March 22, 2022 Ok, got some slightly odd stuff going on with the controllers, appreciate any advice. I have a simple clip on inductive ammeter which I use to check what's going into the controllers. Once properly sunny on the panels, the 4 controlled by the MPPT controller have around 20 A & the 2 with the Giant of sun controller around 10A, but as the voltage stored builds up, to around the 28V or a little above, the MPPT controller starts to cut in & out, roughly once a second, so, ammeter will jump from zero to 10+ then back to zero, once voltage achieves around 28.5 the controller on the 2 panels, appears to cut out completely, ie not recording any amps on the meter, tho' still showing around 27.5V+ on the display & the display shows it to be working, ie showing flow from panels to battery Is the above normal? The MPPT controller cutting in & out suggests it's registering over voltage or current, but display never showing above 28,5V & both controllers are supposed to be rated at 100A, I've never seen more than around 20 on the meter. I'm guessing the 2nd controller cutting out once volatages are high could be simply that it's registering no further top up to float voltage required & therefore cuts out until voltage drops back a little? Just had a look at some of the Pi stuff - I think that may have to wait a while!!! Apologies for numpty questions, like I said this is all new to me & whilst I have good engineering & general electrical knowledge, intricacies of controllers & the like are outside my experience Link to comment Share on other sites More sharing options...
Marvin Posted March 22, 2022 Share Posted March 22, 2022 (edited) 1 hour ago, Solarexploits said: Apologies for numpty questions, like I said this is all new to me & whilst I have good engineering & general electrical knowledge, intricacies of controllers & the like are outside my experience Hi @SolarexploitsNo apologies required. we are all searching for understanding. The good thing with so many people is someone will have knowledge of either there experiences or ways to obtain the info. We have 5.12kW tied to the grid and we are just about to start wiring up the 12V off grid battery set up which is designed to run the MVHR, Grey water system, garden watering and household lights. However the system here will be all mechanical relays and timers. We have set the panels vertical on the wall of a shed as we need as much power as possible over the winter months, and summer we will have excess so we don't need to set them at 35 degrees. For us, our aim is to reduce the amount we buy from the grid. Over the last 4 days we have purchased 30kWh. We are working on how we can reduce this to zero as much of the time as possible. Obviously: no bright days - no way, but we could probably achieve some days. We have calculated using the European solar calculator that panels produce more power than we need over the course of the year, its just the wise use and storage that's the challenge. Good luck M Edited March 22, 2022 by Marvin Spelling! Link to comment Share on other sites More sharing options...
SteamyTea Posted March 22, 2022 Share Posted March 22, 2022 1 hour ago, Solarexploits said: Ok, got some slightly odd stuff going on with the controllers, appreciate any advice. Can you do a sketch of the wiring, and where/how, you are testing it. I am wondering if, when the amps go to zero, the voltage showing is the battery voltage, rather than the charge controller voltage. Link to comment Share on other sites More sharing options...
Solarexploits Posted March 22, 2022 Author Share Posted March 22, 2022 I had no idea how to upload a file to here, so see screengrab below! I'm measuring amps in any one of the 4 positions shown, simple clip on inductive ammeter. The voltages I've been giving are those shown on the display screens of the 2 controllers. When first connecting up those screens show battery voltage of whatever you're powering them with, once panels are connectedvoltage rises to, I assume, whatever it is charfing the batteries at. I have now checked the Giant of Sun controller & that has float voltage set at 27.4V (seems a little low?) factory default, the other MPPT controller, which I've now discovered is an MCU unit, I think float voltage is 28.5V, but can't find the instructions to confirm - I've definitely seen at least 28.4V on that one. If float voltage is set at 27.4V on the other unit would it then stop making an output if it sees a voltage of over that?I believe I can adjust that higher to make it match the other unit Still doesn't explain why the MPPT unit kicks in & out when at high voltages, could that simply also be maintaining a float voltage? In which case I can draw substantially more from the batteries than I currently am Link to comment Share on other sites More sharing options...
SteamyTea Posted March 22, 2022 Share Posted March 22, 2022 (edited) Bit hard to tell what is going on. Can you discharge the batteries tonight and see what happens when they start charging up. I think it may just be fooling itself into thinking the batteries are full because if the voltage and the MPPT is just checking to see if there is any room for a bit of charge. To attach files Edited March 22, 2022 by SteamyTea Link to comment Share on other sites More sharing options...
Solarexploits Posted March 22, 2022 Author Share Posted March 22, 2022 When they are charging, say voltage is down at 24 or 25V, both of the controllers are working & I'm getting around 20A on one string & around 10-12A on the other, so, thinking about it, it would make sense oif the MPPT unit has 28.4V set as the float voltage, then if it achieves that charge would kick in & out at lower level simply to maintain that float voltage? & the other unit would drop out as it "sees" a voltage above it's float voltage? I'll try & get a look tomorrow or Thursday & reset the float voltage of the lower unit, see what happens then - I'll report back in case it helps anyone else in future! Link to comment Share on other sites More sharing options...
Radian Posted March 22, 2022 Share Posted March 22, 2022 Once the controllers see the batteries are full, they will shut off all charging current. Here's a plot from a single 250W module, 24V LiFePO4 battery PV setup I have for my garden lighting: Once charged, absolutely no current goes into the batteries until dawn (just started to discharge at dusk as I grabbed this plot). Link to comment Share on other sites More sharing options...
Radian Posted March 22, 2022 Share Posted March 22, 2022 Hold on a minute... 4 hours ago, Solarexploits said: I have now checked the Giant of Sun controller & that has float voltage set at 27.4V (seems a little low?) factory default, the other MPPT controller, which I've now discovered is an MCU unit, I think float voltage is 28.5V, but can't find the instructions to confirm - I've definitely seen at least 28.4V on that one. Your schematic shows the two solar battery charger units connected to their own pair of paralleled 12V batteries. Those, in turn, are series connected to provide 24V to your inverter. For a start, the 310W panels would probably deliver peak power at around 37V so would not be a good match for 12V whatever the chargers do. But then you say the (charge) controllers show 27.4V/28.4V why would they when connected to 12V? So did you draw it wrong, and in reality have two controllers (with >40V input capability) wired in parallel across your series connected battery pairs? Link to comment Share on other sites More sharing options...
Solarexploits Posted March 23, 2022 Author Share Posted March 23, 2022 You're quite right, I have drawn it wrong! That's what happens when you rush things! The 2 charge controllers are in parallel with one another charging the batteries at 24V. I'll redraw later & repost it The panels have a max o/c voltage of 44, opt. op. volts of 36V, both controllers have max input voltage of 50V, so everything should work fine together at 24V, which it seems to. I think basically I have a lot more available power than I'm using, at present, recent sunny weather, I'm not using the overnight charger which is available for 4 hours at 5p/unit, at all, so there is also spare capacity there My initial idea was to get it all working & see what I'd got in terms of operating capacity, I had already worked it out very approximately, but there are sooooo many variables involved, particularly with whether the sun is shining or not, that I was trying to overallow. As I still have 4 more panels to go up, & at present none of them are permanently fixed & are at too shallow an angle &/or not ideally placed it looks as though I should have a lot more capacity to come I want to keep the fridge & fridge/freezer on grid at present certainly at least until such time as I feel the system is 100% reliable & I'm keeping the large (but relatively temporary) draws from stuff like cooker/kettle & my garage with compressor & welder on grid as a lot of that usage is already covered by power from the existing MCS grid tied array & I didn't want to get into the realms of needing a huge, expensive inverter to handle high loads that are, by their nature not drawn for that long Link to comment Share on other sites More sharing options...
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