Hi,

 

I have a 5.5KW SunSynk inverter setup with 15 kw DIY battery, I have 8x 550w on MPPT2(ENE) and 4 x 450w on MPPT1 (N). Unfortunately I don't have any more roof space facing North, this is the reason for the 450w panels on the North face. Summer time is fine, battery fully charged by 1:30pm. Now in winter I am only getting to +_ 80% battery charge. I want to first add more panels for winter, then later build another 15 kw DIY battery. My thinking is this, I have a micro-inverter (Hoymiles 1.5kw) from my previous system, so on this I could add 4 x 500w panels to give me the +_1.5kw output (at 75% efficiency in winter), this I could connect into the aux connection on the inverter.

The next option is to by an external MPPT charge controller (maybe a Victron), then connect the MPPT controller directly to the battery for now and then parallel the 2 batteries together when I get the next one. I wanted to look at building an awning and adding panels on top of this, it will also face +_ East North East. The other alternative to this is putting up panels facing West for later afternoon sun, but not 100% sure this will be a good idea.

 

If I build or buy another 15kw battery I am going to need a lot of panels to charge these 2 up in the winter. Any thoughts?

40 minutes ago, Greglsh said:

Hi,

 

I have a 5.5KW SunSynk inverter setup with 15 kw DIY battery, I have 8x 550w on MPPT2(ENE) and 4 x 450w on MPPT1 (N). Unfortunately I don't have any more roof space facing North, this is the reason for the 450w panels on the North face. Summer time is fine, battery fully charged by 1:30pm. Now in winter I am only getting to +_ 80% battery charge. I want to first add more panels for winter, then later build another 15 kw DIY battery. My thinking is this, I have a micro-inverter (Hoymiles 1.5kw) from my previous system, so on this I could add 4 x 500w panels to give me the +_1.5kw output (at 75% efficiency in winter), this I could connect into the aux connection on the inverter.

The next option is to by an external MPPT charge controller (maybe a Victron), then connect the MPPT controller directly to the battery for now and then parallel the 2 batteries together when I get the next one. I wanted to look at building an awning and adding panels on top of this, it will also face +_ East North East. The other alternative to this is putting up panels facing West for later afternoon sun, but not 100% sure this will be a good idea.

 

If I build or buy another 15kw battery I am going to need a lot of panels to charge these 2 up in the winter. Any thoughts?

My 1st response is supply the specs of the 450W panels and the new 4x500W for the Hoymiles. Also the direction of these 4 new panels. 

It might be a good call to use the 4x450 and 4x500W on the same MPPT but the specs and direction is important before a better way can even be put forward. 

This way will mean you have 1 management system via 1 inverter. 

If this can work it still leaves the option at a later stage for the external MPPT and may be the Hoymiles. 

As above, panel specs and MPPT specs to be confirmed.

But I think another avenue to investigate is to transfer your 4x450W panels onto the Hoymiles micro-inverter on the AUX input. Then get 4 more of your exact 550W panels, such that you connect two strings of 6 of them onto MPPT1 and MPPT2, either both to the East, which would be easier to connect, or else transfer two of the panels to the West..

That's just taken from a quick search on the Voltage and current specs for the inverter, as well as for some 450W panels. Bottom line, I think you'll find the input current of 4x11.5A to be a motivation to rather use smaller panels on the Hoymiles.

Whether it's a good idea to go East/West depends on when you mostly run your loads, but in general spreading power generation through the day is sensible. eg. Battery recharge in the morning, and Geyser in the afternoon makes sense to produce hot water just shortly before evening sets in. Also spreads risk of losing generation through cloud cover throughout the day. And it means you are less likely to see a time when your total generation from MPPT1 and MPPT2 exceeds 5000W at once, since if you don't have batteries to charge at that time, the output will be cut to just the rated 5000W anyway.

Hi @Scorp007

I was also thinking of changing the 450w panels to maybe even 4x 600w and then use the 450w on the Hoymiles micro-inverter connected to the aux port. I might have to do this in stages and see how much more production i get from this slight increase. Most of my loads are in the morning so East is good, the West facing would help topping up the battery in winter as it only gets to 80% now.

 

Thanks for some of the ideas, still listening if there are others.

38 minutes ago, Greglsh said:

Hi @Scorp007

I was also thinking of changing the 450w panels to maybe even 4x 600w and then use the 450w on the Hoymiles micro-inverter connected to the aux port. I might have to do this in stages and see how much more production i get from this slight increase. Most of my loads are in the morning so East is good, the West facing would help topping up the battery in winter as it only gets to 80% now.

 

Thanks for some of the ideas, still listening if there are others.

Based on your idea of adding another 15kWh battery west would be a good call. 

Look I love my string inverter so I would always say they are great as it gives you the opportunity to switch AC loads/inverter on and off with a simple timer. Always easier than trying to marshal PV DC circuits with expensive items. 

Edited July 4, 20242 yr by Scorp007

@Scorp007 How is your setup done? What inverters do you have etc.

2 hours ago, Greglsh said:

@Scorp007 How is your setup done? What inverters do you have etc.

I use 2xSolis 4g mini string(grid tied). Connected to 4V 3kVA Axpert clone. My back up only needs to provide about 1-2kWh per LS. It is charged by its own 450W panel. I have 6 x 100Ah batteries of which 2 are taken as 8S1P DIY. 

I manage what uses power during LS. I run any load I have 1 at a time. Heat pump of 1.5kW is the largest load I use on inverter. 

Edited July 4, 20242 yr by Scorp007