12 volt grid tie all-in-one unicorn?

[12VoltInstalls]

In a recent thread the idea of ‘stealth’ or ‘guerrilla solar’ grid tie microinverters came up. Since I’d been thinking about that it prompted me to purchase one of these units and use it with some spare panels.

Since then, however, I have been plagued with the fact that I have 800W of panels running off grid and on sunny days have plenty of excess. (I am not grid tied, merely using a 120V/1.2A power supply that holds me at 12.8V at up to 10A for the dark/winter months. It’s doing well.)

Since I have 800W solar that is excess on sunny days and I could go 1200W easily if I chose, I started wondering how to do the same thing as the low-buck micro inverter and use my existing panels. I’m frustrated to find an all in one hybrid that will backfired the grid and work with a 12V system, however.

The MPP 1210 does everything I’d need except it doesn’t support backfeeding the grid (so grid-down disconnect doesn’t matter because of this) and it seems low on solar input capacity/watts unless I’m reading that wrong.

Is there any economical unit that:
- supports 12V battery system
- will grid-tie with grid-down disconnect
- offer grid-charging at battery low voltage
- will also function fine off-grid

Since the 1200W Inverter I use now is sufficient I’m unconcerned with the inverter specs other than wanting to direct up to 800 watts back to my friend’s consumption when the sun provides. They use a lot of electricity so I’m expecting to not ever exceed their grid demand.

I’m setup with lots of 12V and therefore do not to go 24V. This isn’t a necessity project, it’s just entertaining and practical.

Outside of the Schneider or other top-shelf equipment does anything exist to do this? I’m thinking not at this point but I’ve learned a lot the last day or so.

 

[Perelho]

Outside of the Schneider or other top-shelf equipment does anything exist to do this? I’m thinking not at this point but I’ve learned a lot the last day or so.

Are you looking for brand new? I recently picked up some used panels (800w total) and while I was there I was offered the chance to purchase a Uranus NP 3012E - 12v 3000w solar charger inverter. I don't know very much about it, but the dude says it can do AC charging of the 12v battery storage, MPPT solar charging, is a 3kw inverter (pretty sure you can wire up for 115v or 230v, or there may be a 115/120v version out there)

I can only find one document online about it, and it looks like they refreshed the casing, because the one I saw looked "less fresh" (older design)



Wish I could find out more about it. He offered it to me for $250AUD, and said it's basically unused. He offered to "service" it for me before handing it over also. I also wish I knew if that was a good price for the unit.

Maybe you could look for one in your neck of the woods, or online?

 

[sunshine_eggo]

Looks close:

https://www.solar-thailand.com/pdf/DataSheet-PSW7.pdf

 

[Perelho]

Looks close:

https://www.solar-thailand.com/pdf/DataSheet-PSW7.pdf

Yup. That's the only thing I found also. Maybe it's just an inverter, but can use AC to charge the battery also. For solar, a separate charge controller would be necessary.

 

[Perelho]

Maybe you could look at something like this:

MUST PV18 VPM Series 1000W 1KW 12V Home High Frequency MPPT Solar Inverter

203.48US $ 52% OFF|Must Pv18 Vpm Series 1000w 1kw 12v Home High Frequency Mppt Solar Inverter Built In 60a Solar Charge Controller With Wifi Model - Solar Inverters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

 

[12VoltInstalls]

Thanks. I’ll read up later. First day back to work from covid >sigh<

 

[12VoltInstalls]

Maybe you could look at something like this:

MUST PV18 VPM Series 1000W 1KW 12V Home High Frequency MPPT Solar Inverter

203.48US $ 52% OFF|Must Pv18 Vpm Series 1000w 1kw 12v Home High Frequency Mppt Solar Inverter Built In 60a Solar Charge Controller With Wifi Model - Solar Inverters - AliExpress

Smarter Shopping, Better Living! Aliexpress.com

a.aliexpress.com

Thank you for your suggestions. The problem with that is it’s 230/240VAC. Unless the description is incorrect I cannot use that in the USA.

This unit looks sufficient in several ways - except that it doesn’t export to the grid. Description says, “…can start your generator automatically / or j just switch over to utility power if battery runs low during poor daylight / night time. (and recharge the battery at the same time)…”

It doesn’t mention pushing to the grid which is the goal. Unless I’m wrong or missed something.

Seems I’m just going to have to go with the cheapo “gridtie micro inverter” because the equipment that will do what I want is not cost effective for an 800- or 1000W system.

Looks close:

https://www.solar-thailand.com/pdf/DataSheet-PSW7.pdf

This unit looks great, too, but doesn’t push back to the grid, merely switches to grid power when needed.

 

[Perelho]

So, something like this, only for 12v?

204.47US $ 15% OFF|1000w 1200w Mppt Solar Grid Tie Inverter Dc24v 48v 72v 96v To Ac110v Ac240v With Limiter Sensor Battery Discharge Auto-limit - Inverters & Converters - AliExpress

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I think your 12v stipulation is your downfall. Inverting 12v to mains requires a large aH rating for your 12v storage system. It may be better (more efficient and cheaper) to hook up your storage as 24v, and have a 24v DC-DC 12v converter to run your 12v stuff.

Isn't the US 120v system actually delivered as 240v which is split to 2x 120v rails? Maybe it's possible to wire up a 240v inverter in a split rail 120v manner?

 

[Perelho]

 

[12VoltInstalls]

think your 12v stipulation is your downfall

Yes, that is the limitation.
Virtually everything I have is 12V, so

have a 24v DC-DC 12v converter to run your 12v stuff.

this is undesirable.

The grid pushback feature is not necessary for my situation. It’s just that the unanticipated grid backup got me thinking about pushing my excess on sunny days back to my friend’s demand.

I have a cheapo ‘grid tie micro inverter’ that can accomplish maybe 400W with my spare panels but I have 800W running daily for my needs that I don’t use much of on a sunny day (or not winter).

I appreciate the help. I just didn’t realize there wasn’t a demand for a small solar grid push machine. It seems if there was someone would make it.

There are “nice” brand names with equipment that would handle this level of gridtie push very well but with this effort being optional the price tag it just doesn’t make sense. As is reflected in this post.

That 12V MPPSolar unit is great but doesn’t feature the push-to-grid and grid-down disconnect. I’d think or I thought that setup would be wanted but assumed wrong.

 

[12VoltInstalls]

Because the device I desire isn’t available for 12V systems the ponderous Y&H 600W “microinverter” is my in-hand solution. But I may send it back…

The unit has both banana plug and pinch-post solar input connections. While it’s rated 600W, both connectors will barely fit 12AWG which to my recollection is 20A wire. Not a big deal for 100W 2P. However, because of the 21VOC limit I can’t series panels. Not only that my panels are 22.x VOC iirc

To “load it up” to 600W one could do this a couple different ways. Solar is the intended way: if one were to use 100W panels, for example, you could conceivably hit 31.x Amps. Oops! 12ga is 20A. Another method that the manual alludes to is “battery.” So if one anticipates a 12.8V battery input and the device is quiet over 600W… well that’s like 45 Amps.

How exactly is it that they expect you to supply input power to this?!!

I may return it and order this 350W 24V unit as it appears dubious to supply 600W to the unit on hand. The 350W allows 46VOC (it says VOC but elsewhere says max input 50V) and two of my panels could be up around 45VOC at 68*F

Why do they make these for 12ga wire?!

 

[lexio]

440.23US $ 15% OFF|Powland 3.6KW/5.6KW Omvormer 80A Mppt Laadregelaar 220V 24V Input 500VDC Pure Sinus Hybride Inverter met Wifi|Omvormers & Converters| - AliExpress

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nl.aliexpress.com

have this but has a high idle of 40 watt/h edit the 1000 watt version is using 18.5 watt
and a low solar in put of 500 watt
1000 watt of continue out put pf1
makes a lot of noise
the rest a nice machine

 

[12VoltInstalls]

440.23US $ 15% OFF|Powland 3.6KW/5.6KW Omvormer 80A Mppt Laadregelaar 220V 24V Input 500VDC Pure Sinus Hybride Inverter met Wifi|Omvormers & Converters| - AliExpress

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nl.aliexpress.com

have this but has a high idle of 40 watt/h
and a low solar in put of 500 watt
1000 watt of continue out put pf1
makes a lot of noise
the rest a nice machine

Thank you for your suggestion. Took me a minute to figure out how to preference away from Finnish or Taale

40W idle consumption isn’t bad imho

However it doesn’t appear to support 120V- it’s 230V, says it ships from Italy, and says it cannot be shipped to my address…nor to my selected country.

I have a perfectly functioning solar controller and inverter already. I was looking for gridtie to push excess solar to “the grid” snd slow down the electric meter.

If there were a 12V / 120V AIO that supported island protected grid push I’d consider it.

And thank you so much for your kindness in posting!

For $225 I’m going to explore to see what else they have.

 

[lexio]

sorry it is using 18.5 watt on the shunt
40 watt is for the 3000 watt version

 

[Perelho]

Your Y&H 600w Micro-Inverter is meant for 12v class panels. They give an example of 4x 150w panels.

For battery supply, you CANNOT use 12v, it requires 24v, as stated in the specs given in the Amazon listing. So, only 25A. This may be what you need?

As for the DC posts, if you use a 4mm banana plug, you may find it difficult to fit even 12AWG (4mm2) cable in them. BUT, you should be able to find ring lugs or U lugs which could take 4mm2 (12AWG), 6mm2 (10AWG) or 10mm2 (8AWG)

The inverter is good for UP TO 600w input. So, 4mm posts are good for lower input (Minimum input is 120w). If you need the full 600w @ 18v Vmp (max 35A) then 10AWG (6mm2) cable will be struggling. 8AWG (10mm2) can is rated up to 40A.

Look for some Ring/U lugs which will take 8AWG or 10AWG cable with a "hole" big enough to go over those 4mm posts. Get good solid copper lugs with as much surface area as possible to ensure a good conducting connection with the posts.

How heavy is your 12v load? Would it be possible to make a 24v battery, and use a 12v feed off one of the cells? Or get a DC-DC converter and run 12v off the 24v battery. This would probably be the best way to get a better MPPT all-in-one GTI based on 24v storage, run your 12v loads and enjoy your life. Of course this leaves you with an unused 12v GTI.

 

[Perelho]

Maybe solar cable is rated differently. According to https://www.zw-cable.com/products/Solar_Cable_6mm.html 6mm2 (10AWG) solar cable is rated to 70A, while 4mm2 (12AWG) is rated to 55A.

Are you using proper solar cable? 12AWG cable should be fine.

 

[Perelho]

Or you could investigate a 240v inverter, running through a center tapped transformer to get the 120v H1/H2 + N. Look for a 240v - 120v stepdown transformer.

 

[12VoltInstalls]

Thank you for your input!

I’m running a pair of 100W panels parallel on the gti. If I can find my bag of branch connectors I’d be running three or four panels. I was ~160W most of the day.

My actual system is 800W at 12V, and I was 14.6V to the batteries mid morning with 94V from the panels. It was throttling back so I wasn’t using all the power. That was my interest: use my excess power.

My solar cables are mostly 8ga with one 8’ section at 10ga because I think I was impatient or not paying attention. But the run is only 8’ with 88.xVOC so I don’t care.

Look for some Ring/U lugs which will take 8AWG or 10AWG cable with a "hole" big enough to go over those 4mm posts.

I don’t use U-terminals except for audio. I like rings or clamp terminals for anything that can arc.
But the cross-terminal nuts don’t appear to want to go past the retainer. I’m fine with it. I trimmed a few strands which seemed to me better than crimping on a piece of 12ga thhn or something.

How heavy is your 12v load?

I see 7-10A tops. But EVERYTHING is 12V that isn’t a fridge, coffeemaker or vacuum

Would it be possible to make a 24v battery, and use a 12v feed off one of the cells?

A) that would require many new purchases
B) werewolf-tapping 12V off a 24V system is not a good idea

Or get a DC-DC converter and run 12v off the 24v battery.

This isn’t a necessary thing. It was a fun thing I desired to do.
My system works great now. I already bought the gti; spending more than buying the GTI to save 1kWh per day makes no economic sense.

I might have jumped on an AIO hybrid grid-tied if one met my 12V specs but I’d still realize it wouldn’t be an investment it would always be an expense.

I have a few thousand terminal ends on hand, and 50+ feet each of red and black 8ga. I’m going to cut two for U-connectors as a one-time test.

Next time I’m home and it’s charging at 14.6V I may try pulling from the battery to see what it does. I know what the specs of the unit are and what it says about 24V batteries. If the mppt reacts to the 13.x ‘float’ voltage then my spare panels go in storage. I’ll have to figure out how to only run only on bonus/free watts

 

[Perelho]

How about this unit?

96.33US $ 20% OFF|500W Micro Grid Tie Inverter MPPT Pure Sine Wave for Solar PV Panels &12V/24V36V/48V/72V Adjutable Battery discharge|Inverters & Converters| - AliExpress

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Nope, it's about the same as what you have already.

 

[Perelho]

What about this one:

Support WIFI GPRS ETHENET 1000w Hybrid inverter with MPPT solar controller 50a 12v 120v
https://m.alibaba.com/product/1600215073950/Support-WIFI-GPRS-ETHENET-1000w-Hybrid.html?__sceneInfo={"type":"appDetailShare","data":{"filterKey":"7.8.2_share","cacheTime":"1800000"}}

Probably not going to export to the grid, but it can have a 120v device running from it Maybe as close as you will get. Uses a torroidal transformer, so that should mean heavy, but low frequency, which from what I read is desirable, and more reliable.

Found it on AliExpress too:

Low Frequency Converter 1000W 12V/24V Pure Sine Wave Power Inverter

156.0US $ |JNGE Factory Outlet Low Frequency Converter 1000W 12V/24V Pure Sine Wave Power Inverter|Solar Inverters| - AliExpress

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a.aliexpress.com

$141 US + shipping (was $135 US shipping for me, but I'm in Australia, so for you it may be different)