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  1. It's a Tallas D-DW (DW == Dirty Water, there is also a cheaper CW model). After I bought it I noticed the specs on their website says "Temporary use", but if you compare with the DWP (Permanent use) it seems identical except for the bottom part of the pump, perhaps so it requires cleaning less often. It's not a big pump at all, 400W, can do 140liters/minute if you have a big pipe on it, but only 0.7kpa pressure so if you use a hose pipe for "last mile delivery", use a thick one.

  2. No filtering. I capture only the bath and the shower of the one bathroom (which is not used by the wife, so no long hair issues), and no basin water where all the gunky stuff from brushing teeth comes from. The pump is rated for dirty water and will pump larger items up to 30mm in diameter, so it simply throws the water onto the lawn as is.

    If it becomes a problem, I already have a plan for that: Apparently a baby bottle brush pushed into the pipe makes a perfect filter, and cleaning it is simple enough.

  3. That inverter has a RS485 interface. Chances are it speaks SunSpec (over modbus RTU). So a limiter is at least possible in principle, though there is no telling if one already exists. There is a local guy who made a limiter for the Fronius, you might want to chat to him. Somehow I think the Fronius is also sunspec.

    http://chtech.co.za/

    Secondly, it is possible that that inverter supports GFPR (Grid Frequency-dependent Power Reduction). That means that it delivers full power at 50Hz, and linearly reduces the power to zero if you move the frequency up to 53Hz. This is useful in micro-grids/islands, where the GTI ties to another inverter downstairs, usually a Quattro or Multiplus. Probably not what you want to do, as that will more than double the costs.

    The other option would be to not use that inverter, and go with something like an infinisolar, Imeon, or whatever, that has this capability already. I don't know any of these inverters though, can't say I'm a fan of either, but that's the easiest and most cost-effective way of doing it right now.

    The one I know best is the Victron, but then you need to add at least some batteries. You can run this as a hub-1 setup and configure it not to push back into the grid. For best results, you'll want to add a CCGX as well, and you need to get one of the newer models with anti-islanding that complies with NRS-097-2-1. Not all their models are compliant, and then you need a Ziehl UFR1001e, which is another 7k. Basically... much as I love their stuff, I always have to remind people that it is NOT cheap.

  4. 32 minutes ago, The Terrible Triplett said:

    Go grid tie using the smallest possible cheap 2nd hand bank - but do it legally ne!

    I'll be ordering the Ziehl anti-islanding and the current sensor soon (ish). A good 10k worth of equipment (but only 700 Euro, which in European terms is pretty average really).

    That's the last two parts I need, the current sensor is to avoid tripping the prepaid meter. The Ziehl is to comply with NRS-097-2-1. Then to get the paperwork in order, which is likely going to cost some money too, because you have to pay for someone's time to sign it off. Apparently you need like a registered professional electrical engineer to sign off the NRS compliance... and most engineers I know decided not to bother with the professional certification.

    After that, the expansion process is pretty much adding more solar modules and MPPT units.

    32 minutes ago, The Terrible Triplett said:

    for who knows what they future holds

    Indeed. If the future is particularly unstable, that would be another reason to go 48V. If there is a chance that your local municipality is going to be funny with connection fees etc, and you decide to just drop them completely... then you want the big one :-)

    32 minutes ago, The Terrible Triplett said:

    buy a cheap Axpert

    I think that they are 6999 ex vat now. That means a second hand one might go for less than 5. For 3k, I'd take the Axpert. R1/watt for a pure sine wave inverter? Bargain, even if it isn't blue :-)

  5. 26 minutes ago, The Terrible Triplett said:

    If this forum was just 24v and everyone was  shouting 24v, I would have said "Did you know that with 48v ... ": No jokes.

    Agreed... I think that's what I'm sort of trying to do now :-)

    26 minutes ago, The Terrible Triplett said:

    Cost of batts in cities with Eskom, and are you ate home during the day to use the solar power.

    And hence me looking at a hub system. If I can push that energy back into the rest of the house, then all that energy that's just being choked out of the panels right now can be used to run dishwashers and tumble dryers and geysers and stuff like that... without requiring extra batteries. Now I only have to size the battery according to the expected backup load... and bingo. Backup load is <=500W, so I can get away with a 24V system. In addition, all your good deep cycle batteries are larger than 100Ah, perhaps with the exception of the Sonic Gel stuff (that's also available in 50Ah), but generally, the good stuff that will last a long time? 150Ah and up. So I'm EXACTLY in that bracket where a 48V battery bank is just going to cost too much.

    But as you can see, I weighed the compromise very carefully in terms of my end goal. My end goal has always been to take everything below 1kw off the grid, not to go completely off the grid. It's actually very easy to explain this using a good old load chart (watts on the vertical, time on the horizontal). The effect I'm talking about is cutting off everything below a certain point, say 500W for a start. In other words, you move the zero on the Y axis up to where 500 is now... and only the bits that stick out above that is now your consumption. The consumption is the AREA covered by these peaks (watts on the vertical, time on the horizontal, hence the area is watts times time, or some multiple of watt hours)... so this exercise is really about trying to draw a dividing line through the chart such that there is more coloured in area below the line than above (ie bill cut in half), and then discovering you can do this with a small inverter and a 24V bat. Very very specific and highly technical goal. I almost lost sight of it until we had that wind turbine discussion a few weeks back...

    If your goal is to eventually go completely off-grid, pretty please with knobs on... standardise on 48V, even if it means buying crap batteries in the beginning.

    26 minutes ago, The Terrible Triplett said:

    Eskom just lost in court, they are going to have to pull back the increase they applied in April

    Doesn't mean we're not seeing an increase, also doesn't mean price is going back to the old one immediately. Probably means a rebate will be worked into the price and/or a new slightly lower increase will be negotiated with all the relevant two-stroke letters receiving the full treatment.

    Edit: Same thing really for eToll. Yes, court struck it down based on process not being followed correctly, so we won't be getting toll gates in the Western cape YET... but nothing prevents Sanral from going back, actually following the process correctly, and getting there anyway. These efforts to stop someone temporarily are good and all, but sometimes I worry that the underlying problem -- namely that the consumer is seen as a product to be sold, an investment opportunity for those who befriend government officials -- that that is not addressed, or at least not addressed fast enough.

  6. 7 minutes ago, viper_za said:

    Best advice plonkster, why one would even go back down to 24v after running a 48v does not make any sense at all
     

    Don't get me wrong, I can see a case for that, it really depends on what you want to do. I'm also somewhat of a defender of 24V systems, in the sense that the advantages are often overlooked in favour of the mantra that higher is better. Yes, higher (voltage) IS better, and lower (amps) IS better... BUT, TTT has a point. No point in spending 20k on a Trojan battery bank (8 x 225Ah) and then never breaking 800 watts, that would be downright silly.

    Nevertheless, I've shed some of my 24V enthusiasm, mostly because I'm jealous of the low currents the 48V people have. I still think it's a good compromise, and specifically for the target I'm aiming for (a hub system with a small backup component) it makes a heck of a lot of sense, BUT... when handing out generic advice I'm a little wary of pushing too hard for 24V... you know, a newbie is going to buy that advice and be terribly upset a few years down the line.

    You really have to do your homework :-)

  7. 29 minutes ago, The Terrible Triplett said:

    Few lose thoughts:

    You "lost" me there :-P

    30 minutes ago, The Terrible Triplett said:

    IF your constant load is low: 24v

    Still not always sure I agree with that :-) It's rather a long term commitment to buy an inverter for 15 years+ (or at least 5 years) and to think you're never going to need to do a bit more. If you can afford the 48V one, do yourself a favour and just do it. :-)

  8. Depends what people mean by "last". What they usually mean is that the batteries will dip below the set voltage point in less than 4 hours. In theory however, the important part isn't how long the voltage is kept up, but what your coulomb counter (aka Victron BMV) is telling you. If a 12V battery is sitting at 11.5V under load it might be far from empty.

    Of course you cannot completely discount voltage:

    1.If it drops under 10.5V per 12V unit, inverters starts turning themselves off.

    2. Doing the same work at a lower voltage means compensating with more current, and that comes out of the Ah kitty. In other words, voltage efficiency does matter.

    You also have to understand a bit about how  battery works. The amount of energy in it is really proportional to the amount of electrolyte. The rate at which that energy can be liberated is proportional to the amount of lead in it. When the voltage drops, it is an indication that the lead plates are falling behind in terms of charge collecting on them. This might be due to the electrolyte being weak (through discharge), but it could also be that the rate of discharge is just too high and you're not giving the chemical reactions enough time to restore charge to the lead plates.

    With all that said, at 150w on a 48V battery, that is below the C20 discharge rate, and a battery that is supposedly fully charged and is discharged at such a low rate really should be able to keep up the voltage. So however you look at it, even when bringing in some mitigating factors as I did above... still sounds like those are crappy batteries.

    I have a pretty similar capacity, a 24V 200Ah bank (which in kwh is about the same as a 48V 100Ah bank). With my set point of 24.7, in December, when no TV is being watched and it's pretty much the fridge and freezer and a few lights running from it (similar load), that will go until 5AM the next morning before it hits 24.7V :-) It is a pair of Victron AGMs though, so it is too not surprising.

    (Yes, I know an AGM battery isn't the optimum for regular cycling... but they are cheap second-hand ex-UPS, I don't mind if I kill them in 600 cycles).

  9. So I posted this to show TTT how to configure your multiplus to use an input (in this case the temperature input) to tell it to connect or disconnect AC. You can then use your BMV relay to control the multiplus.

    But then I realised, in all our bickering about the greatness/oldness of inverters, I had completely missed just how wonderful the assistant stack is. I don't know any other inverter on the market with this level of programmability. Yes, perhaps overkill for the average home user. I'm not the average home user though :-)

  10. Aaaah okay, not too far off my own frame then. Mine is 40x40 angle iron. The first frame was 5mm thick (seriously over-engineered) but I have since settled for the thinner 3mm type. Have a cheapie welder, but I learned that you can counteract the cheapness of the welder somewhat by using proper rods. Afrox Vitemax works well. Only thing to keep in mind, when you put aluminium on steel, the steel rusts, due to galvanic corrosion. So you want to put some insulation down, rubber, or bitumen strips. Unless you're in the karoo, then it might not matter ;-)

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