coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
I strongly don't recommend connecting 7.2 kW of panels to an inverter (any brand or model) that is rated for 4 kW of PV. I know it will only use what it needs in theory, but the Solar Charge Controllers assume rated panel power (or a little higher), and can overshoot and undershoot quite badly with severly "overclocked" PV. When the Pylontechs disconnect due to over-voltage, unusual and sometimes bad things can happen.
HOOo i did not know that, noted ... i will then use a separate MPPT to deal with the 3.2kW remaining panels.
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
Also, the bifacial panels are quite new; I would call them an untested technology. Do you intend to mount them vertically to get east-west sun, or conventionally on a roof? I've not heard of the former before, and would not know how to mount them safely. The 6 mm thickness modules seem fragile to me (perhaps you are considering the ones with the frames, but those are only 10 mm wide at the top and bottom, and 30 mm wide at the sides). I note that I could not see any 300 W models; the lowest models I saw were 305 W (unframed) and 310 W (framed).
I said 300W, but they are in fact 310-330W :
https://www.jasolar.com/uploadfile/2020 ... 344322.pdf
I will mount them on the ground, vertical 55°, from south 0°, i plan on perhaps creating a kind of "box" around them to preheat the air that come into my house. Box from which the top will be opened in summer.
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
Those will be able to be charged at 37 x 3 = 111 A, which should be able to take the full power of your PV array (nearly 12 A per string, or some 96 A).
Yea that what i've calculated too, i've got little room there, which is good. 10-12A per string, 8 strings.
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26I will perhaps add a "SCC MPPT 3kW" to cover what the PIP can't
I would recommends this (or any other external MPPT). Or a second PIP in parallel to take half the PV strings (see below).
Not sure about the second PIP .. but .. i keep the idea since they do not cost that much more then ther MPPT alone and it could replace my first inverter in case of problem.
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26By "transformer", I assume you mean a DC-DC converter, since your 48 V is presumably DC. This is an attractive idea in theory, but consider the problems:
- A completely separate wiring system, which should be physically separate from the AC system (not sharing the same conduits or channels, for example).
- The difficulty of switching 48 VDC at significant currents. Ordinary AC switches will not be suitable, as they will arc. I get away with AC switches in my house for a few lighting loads, because I use 24 V (makes a huge difference), and the loads are very low power (< 1 A). 95% of my lights, and 100% of my power, are 230 (or 240) VAC. The 24 VDC system is a legacy that I keep as an ultimate backup in case two other systems fail, or something trips the house Residual Current Device.
- The difficulty of fusing DC (fuses are larger and way more expensive)
- 48 V cables need to be some 5 times thicker for the same power level.
Yea sorry, i meant DC-DC converters, i do not plan on using more then 1000W on my 48V circuit, something like 20A.
My water pump will be 1m from the battery pack/inverter (in an underground concrète shed, just under the panels, some tubes are running under ground and are cooling the system, convection act like a natural pump), seems 2.5mm2 is enough. 4 meters from this inverter/battery you draw a circle of 5 meters in diameter and all my electric devices (appart from lighting) will be in it => My circuits are pretty short, i can use 2.5mm2 or even 4mm2 if needed for the 48V. In fact i want to be able to use my important devices even if my inverter fail.
I'm using this table for cable sizes :
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
The goal is to switch the inverter off each night automaticaly, cause those 30W are way too much in my opinion and loss in transforming also add up while my 48V-12V transformers kind lose near nothing.
I note that if you have a charging source (PV all day, or you have utility AC-in at night), then PIP inverters don't switch completely off, even if you turn off the switch. If you don't have AC-in connected, then leaving the switch off will cause the inverter to switch off at sunset, but that's presumably not what you want. Turning off 230 VAC power at night means every clock in the house will lose power (apart from battery powered ones, of course). Personally, I find the clock in the microwave to be very useful.
Yea you are right, i do not want it to switch off at sunset, i want to be able to watch a film or something like that then switch it off when going to bed.
But .. for what i've read, the PIP 5048 got 3 modes : ON under load, ON without load (45W) and idle mode what i call sleep mode which is 15W .. m i right on the values here ? Cause 15W is perfectly acceptable. And if i remember correctly, the peep wake up from idle mode when the "demand" rise over some watts... isn't it ?
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
This is another idea that is attractive in theory, but difficult in practice. You'll need several DC rated contactors, and if you connect to the panel side, it's ~100 VDC, so those are different elements than ones suited for 50 V. Resistive elements draw 4x the power at 2x the voltage; you very likely can't overpower the elements by 300%. You can't ue the ordinary thermostat; it's only rated for AC, so you'll need a special thermostat, or some other sensor, and then there are safety concerns. It likely can be done, but it's very tricky.
What about connecting the resistive elements on the charge port of the pip ? WOuld be something like 35A with all 3 elements on.
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26
My questions : What is the best voltronic / Pip to buy today, i need 5kW, i think i will not need parrallel capability cause 5kw is already plenty for me, and this would double the sleeping energy cost.
I thought that 4 kW would be enough for me (one PIP-4048MS). But now I'm running two in parallel. The main thing I didn't cater for is charging an electric car. You may not have one now, but in 5-10 years, that could well change. So I'd at least get a parallelable model, even if you go with only one inverter for now.
The 450 V or 500 V max SCC models make it easier to wire the solar panels, that's all. PIPs don't have insulation monitoring, so the higher voltage models aren't legal in Australia; I don't know about other countries. There is no patched firmware for the higher voltage SCC models, although there may be one or two lightly patched versions (just fixing the premature float bugs) in future.
Ok you bought me on this one, we already got electric cars, since 1997, i'll go with the 145dc parralel compatible device then..
If i need to add more panels in the futur.. i'll be ready.
One last question, for people that already tried both, would a victron system be really more efficient in terms of sleep energy cost, in term of inverter efficiency, in term of Mppt reaction time.. voltage start up .. ?
coulomb wrote: ↑Sat, 28 Mar 2020, 07:26Total : 2900€ ... vs a PIP 5048MG that would cost me 650€... that a quarter of the price .. !
Wow. I haven't checked the price differential for years; it was something like that ratio back then. I thought the newish Multiplus II was supposed to be much more competitive.
Perhaps there a way to get it cheaper, like 1400€ .. but i'll still need a 4kW MPPT to match the PIP posibilities.