Cobbled together PV in W.Sussex

[fred bloggs]

I'm also glad to see you back, thought you had emigrated to foreign shores.

Look forward to further updates.

Best Regards

Fred

[Scruff]

 

[Tiff]

Great stuff, pleased you are back and sharing your adventures with us!

[Outtasight]

Ever seen those cheap Chinese generators that you often see at car boot sales?



You know, those "6500W" 3-phase generators with an name resembling a cross between processed cheese and an 80's German techno band? The ones that some people buy without realising what "3-phase" means? (other than it has a volt meter that goes up to 450V AC and sockets that don't fit 13A UK plugs?)

Well, I bought this one brand new for £150 and he even delivered it to my house from the car boot sale. He drove off, thinking, "Tank god I got rida dat ting, so I did!" - (yes he was Irish).

But I had a cunning plan...

Remember these?



I've been playing with backup generators for a while. Starting with this one:



The generic Chinese 650W single phase, 2-stroke smoker. £35 from a car boot with free grass in the fuel filter.

It kinda worked with one of the chargers but that wasn't enough, although the fumigation of the neighbourhood was.

So I sold that at a car boot (for £50, minus the grass in the fuel filter) and got one of these:



It was a bit better. Even more noisy but being a 4-stroke engine, easier to start and largely smoke-free. Still only good for running one charger. So I sold that and bought the soft cheese techno generator.

With three extension cables and some adapter plugs, each phase can run a charger at 15A (400W) for a total charge rate of 1.2kW. The thing will run the chargers at up to 20A each (540W / 1.6kW) but it's prone to cutting out after about 30 minutes. At 1.2kW it seems happy to run continuously.

The latest in 2016 spreadable dairy synth electricity looks like this:





Quite a lot of 16.6kHz ripple from the (digital?) AVR.

But with a EMI filter on each extension lead, you get rid of the ripple and are just left with a 50Hz triangle wave.  Close enough to a sine wave to not start a fire, I guess.




Beats the gnarly SIP generator waveform...



The harmonics on that couldn't be filtered and almost cooked an energy monitor that I was using. I sold it to an Irishman and as he drove off I thought, in my best Japanese, "Kamisama! Nuguushimashita... Aaa, yokatta, yokatta!" (God! I got rid of it. Thank goodness!)

So now I can actually charge my house battery at night, in a power cut. It still requires ear defenders and, at 1.2kW, it will still take 16 hours to fully recharge the battery. But should the occasion arise, the neighbours will be in no doubt that I have electricity and they don't.

 

[biff]

I am soooo Shocked Outta,
                        The poor Irishman was only trying to help you. I have no doubt that he knew who you were and was only trying to help you with your electrical problems.
   He is probably now on his bended knees in church, praying to god that you got the phases in the right order , you know,? the last one goes in first and the first one comes out last.
   He more than likely wrote it all down for you. Don,t worry about your £150,00 , It is surely in the hands of some charitable thrust by now,
                                             Biff
   But that is a cracking good idea with the phases.

[billi]

i rather invest in more PV    than  relying on generators too much  , i lost a few gensets   .... worked them too hard (my mistake probably )

It works fine with me since years with a honda clone   petrol now  and  just do not stress her    too much

[Tombo]

Hi Outta, Good to have an update on your electric string wizardry. 
Can you clarify for me please, your 6500W  cheesy techno genset only produces a 1200W continuous output, spread across all three phases?
Thanks and good wizard-ing.

[Outtasight]

Yep, the 1.2kW was evenly spread across all three phases.

For a laugh I tried plugging a 1kW heater into one phase with the others unloaded and the volts on the unloaded phase shot up and the volt meter on the thing read 450V.  The stator phases are excited by the same rotor coil and the AVR has to balance providing more excitation for the heavily loaded phase against over-excitation of the unloaded phases, producing excess voltage on them with no load to pull it down.

It does seem to have some protection though. When I tried cranking up the charger power to 25A (675W) each, the generator would labour and then one of the phases would cut out leaving the other two generating.  So it has some per phase sensing of load or over-voltage and will kill an output.  It does try to restart the phase after a few seconds but the inrush current on the charger and the large step load of the charger finishing its self test and turning on the output causes the phase to crash again.

If I keep the per phase loading of chargers to 15A, the generator is happy enough to have the chargers all turn on at roughly the same time and restart any one of them when running.

I agree Billi, it'll be interesting to see if the engine on this thing lasts long enough on load to need an oil change.  There's no way I'd use it to try and go off grid. Using off peak grid power to reduce my grid bill is a much better option. Cheaper, more reliable, cleaner for the environment (as 54.9% of it is nuclear power and most of the rest is renewables).

As you can see from the photos, I'm maxed out for PV unless I rip it all off and rebuild with modern 330Wp panels and all new or expanded solar chargers.

The system I have is now not about going off grid any more, but sheltering me from grid outages as our crumbing power generation fleet disintegrates and we have black-outs from the dithering and ineptitude of those in control of it.

[Tombo]

Thanks  Outta for the detailed reply. 
Perhaps the 6500W refers to peak output, like cheap stereos where PMPO output is quoted rather than RMS.  In the case of your genset, I imagine this was calculated by the energy expended when running flat out with petrol tank on fire

[Outtasight]

Hmmm... Upgrades! (Nero - The Matrix Reloaded)

For a very long time, my system has been over-subscribed.  That is, it has had more PV on its chargers than they could output.

This often meant that the main Tristar MPPT-60 was maxed out at 60 Amps and the upper limit of charge power of it and the two little 15A chargers was 90A, or 2250W (at 25V) to 2430W (at 27V).  The current limit is the same regardless of battery voltage, so the maximum power delivered increases as the battery voltage increases.

But last week I picked up a used Tristar MPPT-60 and here she is!





With these four chargers, each fed by a different section of the array, I now have a total of 150 Amps of charge capacity which more than equals the amount of PV I have (3580Wp).  At 25V this gives 3750W and at 27V, 4050W.

The new charger on the left takes the feed from the 1640Wp of panels from the roof, while the old Tristar takes part of the wall, patio and garage array (minus the bits that are wired into the small SunSaver chargers already).

We haven't got the high noon sun of the summer now but today the array, on its first day of testing with the new charger, managed to squeak 3486W for 15 seconds into the battery, just shy of 130 Amps.





I modified the load manager software to read the extra logged channel from the new charger, so the stats and graphs are fine.  Both the Tristars are Ethernet enabled, so I could connect to them over the LAN.

I upgraded the firmware on both chargers as I'd not noticed that there were new versions.  Morningstar seem to have finally fixed the issue of the firmware not doing an EQ cycle on the first day (when they're programmed to do one every day).

The eagle eyed (and with long memories) among you may notice that there are some new buttons on the load controller program.  This was to have the water heater come on at a pre-set time and timer, now that my gas boiler is no longer with us.  It still takes 5 hours to heat the water, because it can only go at 650W, but at least we always have hot water in the evenings without me needing to remember to set the boost.  I can also dial in up to 5 hours in 30 minute steps manually on the timer too.

[eabadger]

hello looking good, was that the mppt off ebay?
have gone back a few pages in this post and cant see any more info about the "load manager" is this yours?
i am in process of upgrading my syste,. i have two new tsmppt60 a hub1 and rd1 to add to my existing mppt60 so interested in aggregating data.
i had a couple of mppt fail, not sure why did wonder if it was static discharge after electrical storm, both replaced under warranty, i like the one we have so decided against cheep mppt and went for it.
not sure about doing the battery route, due to cost.
how is your three phase generator going? even on expensive sets sometimes they only monitor one phase for the avr, if you identify the phase they use, use this as your main loading phase, the chinese amaze me with power rating stickers, what is engine horse power? this will be the deciding thing.

steve

[biff]

I have run Chinese genis for years,
                                 Generally speaking they are fine and most of my experiences have been good. I found that the windings are susceptible to damp and dust,
      The yanmar clones go for ever but the geni can and do blow the diodes or shake a wire loose behind the dash.
      Yes, many are way over rated, I have one that says 10kw in big bold letterrs and it has the small Yanmar clone. It is also pull start with no lecky starter.
      It is easy enough started with a power drill. I bought it over 12 years ago and I am stuck with it because I am the only one who can start it. Nobody else wants to
      fool around with a power drill with no power.
       I try and steer clear of Mppt,s, There are not many that can handle 140volts
                                                     Biff

[eabadger]

morning biff, morningstar can do 150v and they now have a new 600v dc mppt. but given price of panels now, maybe mppt days are numbered? however i like the remote monitoring as my solar shed is about 150mtr from house.

steve

[Outtasight]

Nope, a mate of mine locally is packing in his off grid experiment. He's got trees growing in front of the array on public land and the shading on his house got to the point where it didn't work.

He had his first one blow up too. This one is the replacement which has worked fine for a few years.  Mine was one of the very early ones in the UK and has been fine apart from some software bugs (mostly cosmetic, apart from the minor EQ scheduling issue).

It was rumoured (somewhere - don't ask me to find the link) there might have been a firmware issue with doing a soft reset via MODBUS. My mate's one went pop while powering on. I've always made sure to reset my controller only when there was no/low load (or do upgrades at night) and then follow the instructions in the guide (open the array disconnect first and then the battery disconnect.  Restart is the reverse process).

The generator is a toy, sitting in the garage. Not used it except for testing whether it would work at all with my chargers. Backup from the grid is much cheaper and, mercifully, automatic. As the inverter is a UPS, it can source select just by applying AC to the input and the off-peak timers and battery monitoring gear sorts that out for me daily. Using the generator is a last resort (for a dark and stormy night).

The load manager program is mostly mine, based on a VB6 driver & demo app for a Velleman USB I/O board from Maplins.

http://www.maplin.co.uk/p/velleman-usb-interface-board-prebuilt-kit-l92bl

The data acquisition is done by MSView (provided by Morningstar) and outputs to a .csv file that my program then reads and does a bunch of stuff and writes another consolidated .csv file that MSView then opens to draw the graphs in real time.

The graph engine in MSView hasn't been updated in yonks and only has a 16 bit DLL that does the data point management so after a few days it grinds to a halt and crashes. These days I only use the graphs for diagnostics after upgrades. If you don't use the graph module and just use MSView as the data logger, it runs happily for months without restarting.

I sometimes think about trying to get into writing a standalone app on an Arduino, directly reading the MODBUS registers and so on but this works and the laptop server is always on anyway, so I could never be arsed.

VB6 is very long in the tooth and I have to run it in a virtual WinXP machine these days as it won't run on Win7.  Maybe when it finally becomes impossible to maintain the code I'll make an effort. Until then, the motto remains, "Don't touch it. It works."  

[Nickel2]

...given price of panels now, maybe mppt days are numbered? ...
Hmm, not so sure about that. Panels are designed to be worked to produce their optimum output. To me. not using an mppt is like driving a car with the handbrake left on because you get free petrol. Surely energy efficiency is what we should all be promoting, rather than wasting a commodity because it is cheap.