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Advise needed to expand installation


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Hi all,

So after an absolute nightmare since my installation was done 4 months ago, I have to expand my setup to get what I needed and wanted from the get go. But that's a different story entirely.

Current setup is the following:


2 X Growatt 5000 ES inverters, in parallel (Each inverter can take a load of 6000+ watt)

16 X CSun 350 watt panels (2 strings of 8 panels each)

2 X Shoto 5.1kw Lithium batteries


The problem is that the batteries does not take us through the evening/morning until the sun starts shining again, so Eskom kicks in around 2am to charge the batteries. My aim for the system was to be 99% off grid, and for that I now need to expand it, as the installer messed up the energy requirements. I have done quite a bit of research on it, but I need some assistance to be sure I'm doing the right thing and that what I want to do, will work.


I'd like to add additional panels and was looking at the 595w Canadian Solar Mono panels. I'd like high output panels, as I'm running out of roof space facing North. So, can I add the higher output and different make panels to the current strings, so an additional 4 panels to each string? Or should I put the current 16 panels on one string going to one inverter, and the new additional 8 panels on a string going to the other inverter?


As far as storage goes, one option is of course just to add another lithium battery, but another suggestion that was made to me to as the upfront cost is much less, is to use gel batteries.


So affectively, getting 3 gel batteries, which will then charge the 2 lithium batteries when they start to run low? I'm not 100% sure how this will work and also a bit hesitant about the idea, as although the upfront cost is less, gel batteries doesn't last as long, charge as well or are as efficient as lithium.


I'd really appreciate some ideas and assistance with this.



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"so Eskom kicks in around 2am to charge the batteries. " If your only requirement is to allow your batteries to keep you going till 8am then how much power do you used from 2am to 8 am?  Just provide additional battery power to your existing setup to cover this load..My total load from 12:01 am to 7 am is 3.5kWh, so a 5kW battery will suffice if your usage is close to mine.

I would not mix and match panels, and remember that you need to be within the PV voltage and current limits of your inverter. ("16 panels in 1 string")

You will also need to add panels to charge the new battery if your current setup will not cover it.

You need to do a gret deal of checking to make sure your panels + new panels + new battery are all balanced and within the limits of your inverter/s. 

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Best get another Lithium Battery, not advisable to mix your already expensive Lithium batteries with Gel batteries that will most definitely hamper their performance if you manage to make them work together. With the PV panels, connect the 595w ones on their own separate MPPT, do not mix them with the 350W panels because if you do, you should forget about getting more that 350w out of them 😁 . Connect the 16 x 350W on one inverter and the new 595w on the second inverter and don't waste your time and money with the Gel Batteries. Forget about that idea 😁

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@phidz yes, the batteries are fully charged in the afternoon. Just the normal things. We're 3 adults and 2 children, so couple of TV's on until around 10pm and the fridges and the normal stuff that is on/on standby. We've got a gas geyser, so it's not that. Both inverters use about 250-300watt during the time we're sleeping, and I know these inverters use about 70-80watt on standby.

@FixAMess we generally use about the same as you, 3 - 4kWh during the morning hours. I have the last couple of weeks started to switch the inverters over to Eskom around 10pm and then switch back to battery/solar when I get up. As when Eskom charges the batteries during the morning, it uses easily double that.

Reason to add panels, is also to have enough usable capacity to use things like air cons etc during the day and have enough charging capacity to charge the batteries. At the moment I have to switch the pool filter off around 2pm, otherwise the batteries does not have enough time to fill up

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I agree with the above suggestions. If you can't reduce the power usage during the night, the next best thing is to add another lithium battery and the solar panels if need be. The difference in price between the 3 gel batteries and 1 lithium batteries will probably be little.

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