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Mecer 5kva inverter


Brian Chetty
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10 hours ago, Brian Chetty said:

I purchased 2 x 5 kva inverters.

They seem to be old PF0.8 models with the heatsink on top. Made in 2016 or earlier?

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Can someone please tell me how to connect them in parallel to the grid.

If you want to actually parallel them, then you'll be restricted to one phase. Are most of your heavy loads on one phase?

You could wire them to separate phases, not paralleling them. But then you'd want most of your loads distributed pretty evenly across those two phases. Since they're likely only 4 kW units (but 5 kVA), you may run into overloads this way.

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I want solar panels priority then batteries then grid.

That's easy, just use SBU output source priority (setting 01).

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Thank you Coulomb 

It's a good  idea  to do what you say. I have 2 geysers waa thinking of separating them and putting them on timers to only work with solar panels during the day. Whst fi you think?

Another question 

Must the investors be connected in series to the grid or parallel.  I don't want the inverters to feed the grid.

 

IMG-20200930-WA0128.jpeg

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10 hours ago, Brian Chetty said:

Even if its connected to the line? How does it work? 

If connecting it the way i think you want to,you will be feeding 460V (230v from grid and 230v from inverter) into your house on a single phase. Firstly decide which way are you connecting parrallel or one on each phase.From mains to ac in and ac out to house (critical load or what you want backed up) neutrals cannot mix (grid neutral and inverter neutral needs to be seperate). One bank if you running parallel and 2 seperate banks if you running on 2 seperate phases

If this does not make sense than unfortunately you need to get someone that understands or has electrical knowledge

 

10 hours ago, Brian Chetty said:

Will 3s4p work?

Will work but 2S6P is better search and read in forum Coulomb has explained many times why 2S for 70cell is better than 3S 60cell

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1 hour ago, Quwatush Shams (Suly) said:

If connecting it the way i think you want to,you will be feeding 460V (230v from grid and 230v from inverter) into your house on a single phase. Firstly decide which way are you connecting parrallel or one on each phase.From mains to ac in and ac out to house (critical load or what you want backed up) neutrals cannot mix (grid neutral and inverter neutral needs to be seperate). One bank if you running parallel and 2 seperate banks if you running on 2 seperate phases

If this does not make sense than unfortunately you need to get someone that understands or has electrical knowledge

 

Will work but 2S6P is better search and read in forum Coulomb has explained many times why 2S for 70cell is better than 3S 60cell

Ok...the supplier sent me 2 x 5 way combiner box. How can I connect 6 strings each? Do I have 2 change the combiner boxes?

IMG-20200928-WA0111.jpeg

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8 hours ago, Brian Chetty said:

How can I connect 6 strings each?

It's really unfortunate that your supplier sent you boxes for 10 strings when you have 24 panels. It looks like there are three half-positions spare; you will need 4 half-positions to add an extra string in that box.

Easiest way as Quwatush says us to use Y connectors to parallel two strings (per inverter). So you need to use a double current fuse for the input with two strings. For example, 10 A fuses in all but the last position, 20 A fuse in the last position and put 2 strings into that. I think you'll be OK without rooftop fuses for the pairs of strings.

Another possibility is to leave the sixth string fuses outside the box. One extra box could easily take the extra strings for 2 strings (4 fuses).

Your talk of putting inverters in series with the mains has me worried; please get someone qualified to look over your work before powering up.

You will of course need a 2 paralleling kits (parallel board plus cables), and the outputs of each inverter will need their own breaker so that they can be isolated separately. You really don't want to have two inverters paralleled before you're absolutely sure that everything is ready. I always want to use a multimeter between outputs (subtracts their outputs if they are in phase) to make sure that they are synchronised (and without AC-in connected to cheat from). If this makes no sense to you, then you're probably not ready to wire your own inverters.

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Thanks you Suly..I'm in Gansbaai..only option is the one Y connection..

I'm so glad I joined this forum..amazing helpful ppl  here.

I like to connect the 2 inverters in parallel 

And fit 2 timers to prevent  the 2 geysers  switching on at the same time. The only item that uses the 3 phase is the stove that I will like to leave on the grid power. 

I will make a drawing of my connection before I actually do the connection for clarity and approval.

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Good question!!

IMG-20200930-WA0128.thumb.jpeg.ee854785eece1c3f0afd836dfb750e65.jpeg

1 hour ago, Coulomb said:

It's really unfortunate that your supplier sent you boxes for 10 strings when you have 24 panels. It looks like there are three half-positions spare; you will need 4 half-positions to add an extra string in that box.

Easiest way as Quwatush says us to use Y connectors to parallel two strings (per inverter). So you need to use a double current fuse for the input with two strings. For example, 10 A fuses in all but the last position, 20 A fuse in the last position and put 2 strings into that. I think you'll be OK without rooftop fuses for the pairs of strings.

Another possibility is to leave the sixth string fuses outside the box. One extra box could easily take the extra strings for 2 strings (4 fuses).

Your talk of putting inverters in series with the mains has me worried; please get someone qualified to look over your work before powering up.

You will of course need a 2 paralleling kits (parallel board plus cables), and the outputs of each inverter will need their own breaker so that they can be isolated separately. You really don't want to have two inverters paralleled before you're absolutely sure that everything is ready. I always want to use a multimeter between outputs (subtracts their outputs if they are in phase) to make sure that they are synchronised (and without AC-in connected to cheat from). If this makes no sense to you, then you're probably not ready to wire your own inverters.

 

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54 minutes ago, DaveSA said:

The older PF0.8 units only had a 3000W MPPT. What will the effect be having 12x380 = 4560W of panels per Inverter ?

I understand that when you connect in series the voltage increases and the watts remain the same. But when you connect in parallel the watts are added together.

So 2 panels in series will increase voltage 48+48 =96v

Watts will remain 380watts

When you add the 6 strings in parallel the watts will increase to 2280watts

96 volts with 2280 watts in this array..

Am I correct? 

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8 hours ago, DaveSA said:

The older PF0.8 units only had a 3000W MPPT. What will the effect be having 12x380 = 4560W of panels per Inverter ?

Good pickup. It likely won't blow up the solar charge controller, but it might. The problem is the over-shoots of panel current (and hence SCC current and power dissipation). The control system for adjusting to sun intensity, which is not the best even in ideal conditions, is even worse when the panel power greatly exceeds what it is designed for. I highly recommend not "overclocking" by more than about 20% (i.e. no more than 120% of rated nominal power). For this model, that's 60 A x 50 V x 1.2 = 3600 W nominal.

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Hi Guys

I mounted the panels..took coulombs advise 8 solar to each inverter.

Inverter is working from solar. Charging batteries. All is well.

Now its time to connect to DB. This is where I need your help.  Do I connect both inverters output in parallel as per drawing?

I appreciate your help

Screenshot_20201006-132500_Samsung Notes.jpg

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