Inverter for 48v off grid - PIP xxxxx or something else?

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Hyena
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Inverter for 48v off grid - PIP xxxxx or something else?

Post by Hyena »

Hey guys,
I'm looking for an inverter to use totally off grid. I've done a bit of reading but now I'm more confused by all the model subtleties than when I started! :P

My situation is as follows:
48v AVASS battery pack (~20kwhr)
2.5kw solar panels (not adverse to buying more if needed)
Totally off grid, No grid / AC available and never will be (acreage in the middle of nowhere)
It will just be a weekender for now
I dont need a heap of power - 5kw will be more overhead than I'll likely need so won't need to parallel units.
Fridge, lights and occasional use of other appliances (kettle and toaster for a few mins in the morning, microwave at night, maybe a few hrs of TV if we watch a movie, charging laptop / devices)

I was initially thinking something like the MPP solar PIP 5048GK but I see in another thread there's a recommendation for the solarpower24 version, and then there's the ebay no name version that seem to be an unbranded version of a similar thing ?
High voltage version vs lower ? Running all the panels in a string would make for easier wiring but more bitey if there's a wiring / user (me) error. I guess the alternative is running 2S5P of my 250w panels at a small efficiency hit ? I guess running more parallel strings at lower voltage is easier to add more panels later ?

The other consideration is turning the inverter / load off.
Given I'll be away for weeks at at time I dont really want it cycling the batteries just to keep an empty fridge running. Or is such shallow discharging negligible in the grand scheme of things ? I was also thinking it is pointless having the inverter running continuously, and it'd be better for longevity to only turn it on when in use. I'll probably be pulling down around 10kwhr/day from the solar panels and only using around 5kwhr so it should be enough capacity for few days at a time even if it's overcast. The other thing is I could rig up some sort of timer (mechanical or otherwise) that allowed the battery to fully recharge for 2-3 days after I leave and then shut down ? Not sure what I can / can't program in these things until I get my hands on one I guess, but want to make sure I buy the correct unit the first time.

Thanks for any suggestions.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by jonescg »

Hi Jay, hope the paddocks are starting to green up after the fires. Got a new shed / dwelling on the way?

I think the MPP Solar options are the most cost effective off grid solutions. From memory they will take three panels in series (145 volt OCV) but they only have a single MPPT input. Which is fine considering the demands you're likely to have. Charging an electric trail bike might dint the battery a little.

Otherwise you can get a Victron solar charge controller and a separate 48 V to 240 V AC battery inverter. At least this way you can run stuff like lights on 48 V DC. Should the inverter ever pack it in, you can still see what you're doing at night.

https://www.victronenergy.com/upload/do ... 20-EN-.pdf
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

We use the MPP Solar PIP 4840MS on quite few jobs, some of them single inverters and others with 2 inverters in parallel. The only real advantage of going 24v rather than 48v is keeping the cells balanced enough to not cause a cell voltage run away, the biggest killer of off grid lithium cells.
The MPPT controller in these units can handle an 80 amp output and max open circuit voltage of 145vdc as Chris has already mentioned. This is the same for both the 24v and 48v units, but the 24v unit is only 4kW where the 48v unit is 5kW.
You will need some sort of cell voltage monitoring that will cut the charging if a cell goes over 3.6v before the total battery voltage reaches 56v (3.5v per cell for a 16 cell 48v battery).
As far as turning the solar and inverter off and on, if you have a reliable BMS with charge cut for high cell voltage and load cut for low cell voltage, there is no real value in turning it off. You can't leave lithium cells fully charged, they don't like it and deteriorate rapidly if you do, so you would need to discharge the battery to 3.3v per cell or less each time you want to leave it in storage mode. Easier to just let it run and power the fridge or what ever.
So, up to you to decide if you want to go 24v or 48v. The easiest to keep in balance is a 12v battery, but there aren't a lot of inverters available with a decent output besides the Victron Multiplus range and they aren't cheap. If you only wanted a max of 2000w the Projecta IP2000 is a very reliable unit and MPP solar sell their MPPT controllers with a 60 amp output capacity that could handle the solar part.
There is another brand Rich Electric, they were sold by Jaycar a while back but they stopped selling them. They are still available from Taiwan or there is a bloke in Qld that was dealing with them that might be able to get one in for you.

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by paulvk »

You may not need parallel units now but if you think you will in the future you could find that you will have to buy two new units then
because the model is no longer available as those with the PIP4048s have found.
Also with the MPP inverters get twice the power you will think you need , motors need big starting power and people underestimate their power needs!
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by Hyena »

jonescg wrote: Tue, 25 Feb 2020, 15:22 Hi Jay, hope the paddocks are starting to green up after the fires. Got a new shed / dwelling on the way?
Hey mate, there's signs of life but regrowth is particularly slow. I had alot of pines where the shed is going and they burn hot and fast so everything is pretty decimated :|
Still chasing contractors for the slab etc but shed is probably a month away at least.
From memory they will take three panels in series (145 volt OCV) but they only have a single MPPT input
Yeah I can parallel them all up easy enough to create a single input - only issue is I need to drop a panel or find 2 more to create the 3P groups. 2 more would be my preference, and 250w panels shouldn't be too hard to come by now.
Charging an electric trail bike might dint the battery a little.
No e-braaap for now - I'm regrettably going to the dark side. It's a bit of a no brainer though when you're on a large acreage where noise doesn't matter, power is scarce and you can jump on a decent used bike for 2-3k.
Otherwise you can get a Victron solar charge controller and a separate 48 V to 240 V AC battery inverter. At least this way you can run stuff like lights on 48 V DC. Should the inverter ever pack it in, you can still see what you're doing at night.
Yeah Victron would be the way to go if budget wasn't a concern. But as always, it is! I was thinking I'd have some backup 12v lighting anyway running off a lead acid battery with a $20 regulator and a single dedicated ~200w solar panel. This will be the first thing that goes into the shed once it's built and will do to rough it while I do all the rest of the wiring properly, then remain as a backup / fail safe. I also have a little 180w victron I could use to run the fridge off too if needs be.

T1 Terry wrote: Tue, 25 Feb 2020, 16:18 The only real advantage of going 24v rather than 48v is keeping the cells balanced enough to not cause a cell voltage run away, the biggest killer of off grid lithium cells.
Cool. I hadn't considered going 24v but I guess it's an option. As you said it's best to have the overheads of a 5kw system though.
You will need some sort of cell voltage monitoring that will cut the charging if a cell goes over 3.6v before the total battery voltage reaches 56v (3.5v per cell for a 16 cell 48v battery).
I haven't gotten that far yet but look into that before go time. Is the 3.6v cut off a conservative / safety HVC ? Are they not 3.7v like others of the same chemistry ? Not that I'm worried, I planned to conservatively charge anyway. And I bought 2 spare cells in case one or 2 lets go.

As far as turning the solar and inverter off and on, if you have a reliable BMS with charge cut for high cell voltage and load cut for low cell voltage, there is no real value in turning it off.
I just thought they are likely doing *something* while sitting there powered up, even with no load.
You can't leave lithium cells fully charged, they don't like it and deteriorate rapidly if you do, so you would need to discharge the battery to 3.3v per cell or less each time you want to leave it in storage mode. Easier to just let it run and power the fridge or what ever.
Cool, I guess I'll play it by ear once set up but it sounds like simply turning it off when I leave may leave it at the desired state of charge anyway.

paulvk wrote: Tue, 25 Feb 2020, 17:03 You may not need parallel units now but if you think you will in the future you could find that you will have to buy two new units then
because the model is no longer available as those with the PIP4048s have found.
Also with the MPP inverters get twice the power you will think you need , motors need big starting power and people underestimate their power needs!
5kw is already around twice the power I'll need, so I reckon it'll be right. I wont really be running any motors that I can think of. Maybe a water pump but again that'll probably be 12v.
There'll be no air conditioning and heating will come from a wood fire. Cooking will be largely gas or wood fired too, with occasional microwave usage - so that'll probably be the biggest immediate / bulk power drainer.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

If that is your maximum planned loads, I'd go 12v and use a Projecta IP2000 inverter and an MPP Solar MPPT solar controller. We build a lot of systems like his for caravans and motorhomes and as long as they are happy to turn the roof top rattler air con off before powering up the microwave or air fryer, the system runs well with no problems. Even if they forget, the inverter screams murder at them and if they take too long to turn the overload off it just shuts down and requires a shut down reboot to start it up again.
With a 12v battery pack you have all the lighting and water pumps etc covered. One of the small Victron inverters like these https://www.ebay.com.au/itm/Victron-Pho ... SwU51du2PC will run a modern inverter type 240vac household fridge indefinitely. We swap out a lot of 3 way and dead 12v compressor fridges for the 250ltr 240vac fridge freezers in RV's and houseboats and use these little Victron inverters. The price difference going that way compared to a dedicated 12v or 3 way fridge makes it a no brainer and they work much better as well yet use less battery power.
You could still go 24v because all the above items are available in 24v as well and the PIP4024MS has an MPPT controller built in so cheaper that way. You can still use12v lighting, just 2 in series to handle the 24v. Our Hino motorhome is set up that way and has no gas appliances except for one of those gas canister stoves for cooking outside if what we are cooking needs a flame and would stink the inside out for ages afterwards. We have a split system air conditioner, air fryer, electric hot water, 240v kettle and toaster, 240v fridge/freezer and all the smaller household kitchen stuff you can think of including the bread maker and rice maker. With 1.6kW of solar on the roof that also acts as a sun roof, we often turn the air con and/or the hot water on to use up the solar rather than wasting it. The whole thing runs off 200Ah @ 24v of Winston lithium battery and that is the starter/bus battery as well.

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by Hyena »

T1 Terry wrote: Wed, 26 Feb 2020, 11:48 If that is your maximum planned loads, I'd go 12v and use a Projecta IP2000 inverter
Battery voltage / configuration isn't really an issue. Are the Projecta's better quality ? Seems like they're around double the price of the MPPT option and limit my peak power by half so I'd be less inclined to go that way unless I'm missing something ?
We swap out a lot of 3 way and dead 12v compressor fridges for the 250ltr 240vac fridge freezers in RV's and houseboats and use these little Victron inverters. The price difference going that way compared to a dedicated 12v or 3 way fridge makes it a no brainer and they work much better as well yet use less battery power.
Cool. Our fridge and microwave were destroyed in the fire so we'll be starting over anyway, but with an increased energy efficiency focus.
We have a split system air conditioner, air fryer, electric hot water, 240v kettle and toaster, 240v fridge/freezer and all the smaller household kitchen stuff you can think of including the bread maker and rice maker. With 1.6kW of solar on the roof that also acts as a sun roof, we often turn the air con and/or the hot water on to use up the solar rather than wasting it. The whole thing runs off 200Ah @ 24v of Winston lithium battery and that is the starter/bus battery as well.
That's a good benchmark to go off, thanks.

I was planning to have an instant gas hot water system (or even wood fired to keep it all minimalist and self sufficient) and no AC, but making use of those extra free electrons in summer is appealing!
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by coulomb »

Hyena wrote: Wed, 26 Feb 2020, 10:11 Cool, I guess I'll play it by ear once set up but it sounds like simply turning it off when I leave may leave it at the desired state of charge anyway.
I believe so. With panels connected and the inverter switched off, it should wake up each day and charge the battery to the float voltage (make sure it's around 3.36 VPC), and should not boost it to the absorb voltage as long as the idle consumption overnight doesn't reduce the battery voltage much. Idle consumption for a 5 kVA model is around 35 W when switched off (inverter-proper not running).
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

The Projecta IP2000 is a good strong unit and has a zero draw standby feature, it does still use a sniff of battery power to keep the capacitors charged, but really very frugal at zero load. The PIP inverters are power hungry just sitting in standby mode so enough battery and solar to just cover that needs to be added to the energy spread sheet to determine just how much of both battery capacity and recharging capacity would be needed.

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by Hyena »

coulomb wrote: Thu, 27 Feb 2020, 08:09 With panels connected and the inverter switched off, it should wake up each day and charge the battery to the float voltage (make sure it's around 3.36 VPC), and should not boost it to the absorb voltage as long as the idle consumption overnight doesn't reduce the battery voltage much. Idle consumption for a 5 kVA model is around 35 W when switched off (inverter-proper not running).
Ah, so the internal sub components of the inverter and regulator/charger can be switched on and off independently ? These are the things I wouldn't have known until getting one in front of me. Thanks :)
T1 Terry wrote: Thu, 27 Feb 2020, 11:43 The Projecta IP2000 is a good strong unit and has a zero draw standby feature, it does still use a sniff of battery power to keep the capacitors charged, but really very frugal at zero load. The PIP inverters are power hungry just sitting in standby mode so enough battery and solar to just cover that needs to be added to the energy spread sheet to determine just how much of both battery capacity and recharging capacity would be needed.
That wouldn't be an issue with the PIPs in my set up - with 20+ kwhr of battery I'd only need half an hour of sun light per day to keep it topped up.

I think I'm pretty settled on the PIP now, the only consideration is you've prompted me to think about whether I should go for a 24v or 48v set up. Other than the peak power it looks like the charging current would also be limited to less than my solar panels can put out (especially if/when I get more) so I'm thinking 48v is the way to go.
So the question now is which specific model ?
Any preferred vendors ?
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by coulomb »

Hyena wrote: Fri, 28 Feb 2020, 06:19 Ah, so the internal sub components of the inverter and regulator/charger can be switched on and off independently ?
Well, the Solar Charge Controller is powered solely from the PV input; never from battery or AC-in. So it automatically is "switched off" at night. The rocker switch (or power button in other models) essentially tells the firmware to turn on or off the inverter-proper, i.e. the DC to AC converter that generates the 230 VAC from the ~400 VDC. That components consumes about 15 W, plus load related losses.
I'm thinking 48v is the way to go.
It certainly reduces the battery current for a given load, allowing for smaller battery cables etc. Also, patched firmware is only available for 48 V models :) I would recommend it.
Any preferred vendors ?
MPPSolar seems to have a warehouse in Australia, at least for the most popular models. So ordering from them (via eBay, vendor MaximumSolar) means quick delivery. However, you might not be able to get certain models from them, e.g. the 58.4 V models where 64 V equivalents exist. I hope they change their policy on that; the 64 V models produce poor output quality at low battery voltage.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

I think I'm pretty settled on the PIP now, the only consideration is you've prompted me to think about whether I should go for a 24v or 48v set up. Other than the peak power it looks like the charging current would also be limited to less than my solar panels can put out (especially if/when I get more) so I'm thinking 48v is the way to go.
So the question now is which specific model ?
Any preferred vendors ?


Doesn't matter if you go 24v or 48v, the PIP MS is the better option. If you go 48v you will still have the issue with 12v lighting, with 24v the lighting can run from the same battery pack. If you want to add more solar you can add one of the MPP Solar MPPT controllers, they have battery voltage sensing wires so the problems with trying to get 2 MPPT controllers to work together is solved because the actual battery voltage stays fairly stable compared to the voltage seen at the battery output terminals at the controller.
We have fitted quite a few of both the 24v in parallel and the 48v in parallel and another system with a single 24v unit and all work well, just the 48v systems are a lot harder to keep balanced if the system works hard and you have a lot of solar. The simple cell top balance boards are inadequate to cope with the high charging currents seen in an off grid house set up where the primary charging is via solar. It can be done but it requires 5 x 4 cell balance units, one for each 4 cell 12v battery and one to balance the 4 x 12v batteries. With a 24v unit it only require one balancer and the cell groups balanced in pairs. As long as you have a high cell charging cut to stop a cell running away above 3.6v the cells remain close enough to balanced to be not worth worrying about. As far as I'm concerned, an off grid house battery only needs to keep the out of balance under 150mV, anything more than that just has the system chasing its tail.

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by jonescg »

If you are happy with incandescent lights, buy a few packages of 12 volt halogens and put 4 or 5 in series. 48 V DC lighting in a house is pretty nice for reasons I described earlier.

24 volts is fine too, and less sparks when switching. Plus that also means less BMS to concern yourself with.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by reecho »

I have a MPP Solar 2424MSE surplus to requirements here. It was used on a set of AVASS cells for a bit. Any interest?
IMG_20200229_093248.jpg
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by offgridQLD »

I run a 3 bedroom offgrid home full sized 550lt fridge/freezer + 2nd small upright freezer, microwave, dishwasher, washing machine, water pressure pump, a few small inverter split system AC .(used on heatwave days) Kitchen has all the mod cons I would say its a typical home. Though we have wood fire heating and LPG for cooking (use induction cooker over summer when we can) and 30 tube 300lt solar hot water. (very little boosting required).

I also run some large loads in the shed though they are for shorter periods high demand but low total consumption. For example when I am welding something or running air compressor and other power tools.

My recommendation would be go 48V no real reason not to and a few advantages already mentioned. I would keep everything in the house AC keeps it simple and mainstream when replacing appliances in the home. Use standard AC powered LED light fixtures they are so main stream now they represent great value. 10w downlights with 800 - 1000lm each depenting on what setting you have them on is all I use.

Our typical average 24hr AC consumption is 5.5kwh. Though it can fluctuate between about 4kw and 7kwh
feb 2020 consumption.GIF
feb 2020 consumption.GIF (164.39 KiB) Viewed 1945 times
Rough breakdown of that 5.5kwh over 24hrs consumption ….
fridge / freezer 1kwh
dishwasher/ washing machine 1kwh
freezer 0.5kwh
water pumping 0.25kwh
lights 0.5kwh
modem, repeaters, tv booster, data logger, 0.4kwh
Tv, PC, laptops, stereo 0.4kwh
kitchen appliances 0.25kwh
Shed 0.3kwh
SHW circulation pump 0.3kwh
Miscellaneous loads, vacuum cleaner, extractor fans, exhaust fans, BMS cooling fan 0.5kwh


This home is In Southern part of SA.To power this I have 5000w of 2nd hand solar panels facing NNW and 16x 400ah lithium battery 48v (20kwh storage) I do have a PIP 4048 and have run the house from just the one PIP in the beginning while setting up (though I now have a larger 8kw inverter) the only problem you would have with just one pip is needing to stagger loads . For example if your running the microwave and Coffey machine at the same time and some one wants to start the dish washer you soon run out of breathing space. Though if you are powering a part time home and are willing to make some small adjustments one PIP inverter would fine. One thing that helps is appliances and motors with soft start. For example my pressure pump, split system AC even vacume cleaner ramps up so gentle with soft start that you can avoid large spike loads on the inverter.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by coulomb »

Did the pressure pump come with soft start, or did you add something external to soft start it?
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by offgridQLD »

The pressure pump has a built in VSD controlling the motor that was purchased set up like this. I can dial in a pressure setting at the pump controller (I have it set low just 40psi as that's all you really need for domestic water) The VSD will reference the pressure sensor to adjust the motor speed to maintain a constant water pressure. Maintains the same flow even when turning on multiple taps so you can keep the pressure low and still get adequate flow with multiple taps on at the same time. Most of the time it only consumes just over 100w when taking a shower but can consume up to 1000w if you set it to max pressure and open all the taps. There are some big brand names that sell them (though very expensive) this one was the best cost vs quality I could find.
https://www.ebay.com.au/itm/VFI4-5-6-BO ... 2749.l2649
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by Hyena »

jonescg wrote: Fri, 28 Feb 2020, 10:10 If you are happy with incandescent lights, buy a few packages of 12 volt halogens and put 4 or 5 in series.
Ack, how prehistoric :P
I think worst case I'd run a seperate step down for LED lighting - but as below it sounds easier just to keep it all standardised.

reecho wrote: Sat, 29 Feb 2020, 09:30 I have a MPP Solar 2424MSE surplus to requirements here. It was used on a set of AVASS cells for a bit. Any interest?
I think I'm pretty sold on a higher powered 48v unit now - unless it's cheap enough to use as an accessory system for another project...

offgridQLD wrote: Mon, 02 Mar 2020, 11:35 I run a 3 bedroom offgrid home ....
Great breakdown, thanks! My house at home, albeit physically larger seems to chew through 20kw a day on average with no AC or heating. I'm not sure what my wife / kids use all the power on but I use bugger all leaving my computer / modem on and as like you the occasional short burst of high load in the workshop.
if your running the microwave and Coffey machine at the same time and some one wants to start the dish washer you soon run out of breathing space.
That shouldn't be an issue - there won't be a dishwasher so at most it'd potentially be the microwave + kettle or toaster on together - and that's easily staggered.
I'm not sure how much gravity fed pressure I'll get yet but my main tank will be 1m above ground level, with a smaller 1000L tank on a 3m hill above the house. The plan is for regular usage to come from the top 1000L tank, which will be topped up from the main tank by a small solar pump which will trickle water up there when the sun is out. And if anyone manages to use more than 1000L in a day I'll be coming for them!
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by Honu »

Hi all,

I got pretty much the same desire as the poster, my house is under construction and i planned on :
- 24x300W Panels (JA solar Bifacial: https://www.jasolar.com/html/en/2018/en_smodule/8.html)
- 10kwh of Pylontech (3xUS3000) (those already got their BMS : http://www.pylontech.com.cn/pro_detail. ... 121&cid=23)
- A 5kW Pip 5048.

I will perhaps add a "SCC MPPT 3kW" to cover what the PIP can't but this is non mandatory since i can connect all my 7.2kW to the PIP : 3x8 / 125vx80A and i do not really need more power in summer, just want a decent power in winter.
(https://voltronicpower.com/en-US/Produc ... l/SCC-MPPT)

I will create 2 electrical cicruits in my house, one 48V and one 220V ... those circuit are pretty simple, i will step down the 48V circuit with transfomers depending on what is needed, 5V here .. 12V here... all my lighting will be on the 48V circuit, my pump will also be on it. 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'm also planning on using the unused energy to power my water heater, for that i will use an arduino and a small decicated solar panel (or just a led if precise enough) which will inform me on how much energy is available(led will give me insolation, i will evaluate what is available on my 24 panels, i got a smart algorithm in mind.. well .. at least it seems smart to me .. :D ).. i will then switch my water heater resistors accordingly, i will use 3x48V resistors : (200W, 500W and 1000W) => 200W > 500W > 700W > 1000W > 1200W > 1500W > 1700W are possible. I'm planning to connect those resistors directly on the charging port.. does it sound stupid ? (to avoid the inverter loss) Or i could eventually connect them directly to the panels .. but this solution is kind harder to build, but could be even more efficient..

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. Are those with the High pv voltage (500V) more interesting then the 145V max pv voltage ? (PIP MS, MK, MG, GK ..?)

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 .. ?

Cause a victron would cost :
- SmartSolar 150/70 (4000W panels like the PIP) : 760€ (i'm in Europe)
- MultiPlus-II 48V 5000W : 2100€

Total : 2900€ ... vs a PIP 5048MG that would cost me 650€... that a quarter of the price .. !
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by paulvk »

I would not be running 48v for lighting even with the loss in the inverters 230v led lighting is much more efficient.
I have compared 12v led lighting to 230v and I can light a whole room brightly with two 10 watt 230v down lights
I could use 40 watts of 12v and not get it that bright
I have 48v DC gear running off my system modem , ether net switch , wifi access point, 48v soldering irons and a number of other things
but these were there long before solar.
For hot water you can get 48v elements but I have a 3600watt 230v element that is two 1800watt in parallel
so it can be 3600 , 1800 , 600 watts with relay switching
Others have used SCR solid state relays to pulse width modulate the element.
Some others turn off one PIP during the night to save power.
Victron is a good brand but as you see 4 times as expensive you can put the extra money into more batteries and panels.
I run two homes with parallel PIPs and purchased 6 units to have two spares nearly 6 years and they are still spares.
There is one type of motor I do not run with my PIPs that is brushed AC motors, vacuum cleaners and power tools
these type of motors put voltage spikes on their power source and as the PIPs are transformer-less
the out put semiconductors are directly exposed but with battery power tools and vacuum cleaners so common
I do not use the others much now.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by coulomb »

Honu wrote: Sat, 28 Mar 2020, 01:41 - 24x300W Panels (JA solar Bifacial: https://www.jasolar.com/html/en/2018/en_smodule/8.html)
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.

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).
- 10kwh of Pylontech (3xUS3000) (those already got their BMS : http://www.pylontech.com.cn/pro_detail. ... 121&cid=23)
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).
I 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).
I will create 2 electrical cicruits in my house, one 48V and one 220V ... those circuit are pretty simple, i will step down the 48V circuit with transfomers depending on what is needed, 5V here .. 12V here...
By "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.
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.
I'm also planning on using the unused energy to power my water heater, for that i will use an arduino and a small decicated solar panel (or just a led if precise enough) which will inform me on how much energy is available(led will give me insolation, i will evaluate what is available on my 24 panels, i got a smart algorithm in mind.. well .. at least it seems smart to me .. :D ).. i will then switch my water heater resistors accordingly, i will use 3x48V resistors : (200W, 500W and 1000W) => 200W > 500W > 700W > 1000W > 1200W > 1500W > 1700W are possible. I'm planning to connect those resistors directly on the charging port.. does it sound stupid ? (to avoid the inverter loss) Or i could eventually connect them directly to the panels .. but this solution is kind harder to build, but could be even more efficient..
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.
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.
Are those with the High pv voltage (500V) more interesting then the 145V max pv voltage ? (PIP MS, MK, MG, GK ..?)
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.

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 .. ?
Total : 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.
Nissan Leaf 2012 with new battery May 2019.
5650 W solar, 2xPIP-4048MS inverters, 16 kWh battery.
1.4 kW solar with 1.2 kW Latronics inverter and FIT.
160 W solar, 2.5 kWh 24 V battery for lights.
Patching PIP-4048/5048 inverter-chargers.
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by paulvk »

Victron MultiPlus 48/5000/70-100 230V VE.Bus $2,475.00
Then you have to get an MPPT charger 60amp 48v $700
so $3175 to get one PIP
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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

paulvk wrote: Sat, 28 Mar 2020, 10:33 Victron MultiPlus 48/5000/70-100 230V VE.Bus $2,475.00
Then you have to get an MPPT charger 60amp 48v $700
so $3175 to get one PIP
A major downside to the Victron products, they don't handle the Australian heat very well. They de-rate at an internal temp of 40*C and shut down at 60*C. Where we see ambient temps of 50*C these things wouldn't be much more than a wall decoration.
The Rich Solar units are supposed to handle 70*C, not a great deal of support for them unfortunately.
The PIP PCM60X MPPT controllers had been great up until the last 3 we purchased. one out of three actually work properly, the other 2 won't read the battery sensing wire connections so the charging cuts off early and we can't control the charging stop by sending a slightly higher voltage to the battery sensing wires. Trying to get through what the actual problem is to the support people has proved to be "testing" to say the least. Fortunately my wife has been handling that part or they would be breaking out the Chinese/Australian translation manual to determine what I had actually said in my reply :lol:
Getting people who have lived al their life in a cold climate to understand there are places in the world that are much hotter than where they live and aren't part of the Arab States, has proved to be rather difficult as well, the thought it could exceed 40*C even in the hottest days is completely foreign to their way of thinking.

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by T1 Terry »

paulvk wrote: Sat, 28 Mar 2020, 07:04 I would not be running 48v for lighting even with the loss in the inverters 230v led lighting is much more efficient.
I have compared 12v led lighting to 230v and I can light a whole room brightly with two 10 watt 230v down lights
I could use 40 watts of 12v and not get it that bright
I have 48v DC gear running off my system modem , ether net switch , wifi access point, 48v soldering irons and a number of other things
but these were there long before solar.
For hot water you can get 48v elements but I have a 3600watt 230v element that is two 1800watt in parallel
so it can be 3600 , 1800 , 600 watts with relay switching
Others have used SCR solid state relays to pulse width modulate the element.
Some others turn off one PIP during the night to save power.
Victron is a good brand but as you see 4 times as expensive you can put the extra money into more batteries and panels.
I run two homes with parallel PIPs and purchased 6 units to have two spares nearly 6 years and they are still spares.
There is one type of motor I do not run with my PIPs that is brushed AC motors, vacuum cleaners and power tools
these type of motors put voltage spikes on their power source and as the PIPs are transformer-less
the out put semiconductors are directly exposed
but with battery power tools and vacuum cleaners so common
I do not use the others much now.
Hadn't even thought about that, but a very valid point and could be the cause of my inverter failures. Could I put a filter on the 240vac supply to protect the semi conductors from the voltage spikes?

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Re: Inverter for 48v off grid - PIP xxxxx or something else?

Post by paulvk »

A problem I find with the PIP MPPT chargers is they are slow to re-calibrate thus the battery will end up having
all the load applied to it until they do. I have Esmart 3 chargers and they simply ramp up, with my small set of T105
batteries now 6 years old its becoming a problem so I am going to move more panels to the Esmart 3
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