Adding more panels to charge batteries clarification

[GFruge]

Call me whatever you’d like, but I need some clarification.

Back in September of this past year, we installed a grid tied system to our home. However, I’ve been looking into other alternative ways to generate electricity to store to those unfavorable days. I’ve checked wind and hydro, but it just doesn’t seem to generate enough or not cost effective. With either system, I’d need to add a charge controller to charge the batteries with either.

The system I bought can only have 6,000 watts of panels. We purchased 10 530 watt panels. So, we’re at 5,300 watts worth. The guy that sold me the system at the time told me that I could technically add 2 more of those 530 watt panels and still be good though it’s 6,360 watts worth. So, pending with him is to buy 2 more panels and 1 more 48v 125ah battery. This will make 3 batteries total. So it seemed like a dead end on production and storage.

Here’s where I need clarification. With the other systems, I’d have to add a charge controller and the energy produced is limited to the charge controller.

So in essence, I could add as many solar panels as I desire as long as I don’t over-do the charge controller? The inverter will only supply up to the 6kw that I need, but aside from that, I could do as many charge controllers to the batteries and as many panels as I want? Is this how it works?

 

[timselectric]

First question is what inverter do you have, that is grid tied with battery backup?

 

[rmaddy]

You can put more than 6kW of panels on a charge controller that only supports 6kW of solar. You'll never get more than 6kW at any one time but having more panels gives you more production during a longer portion of the day or under less favorable conditions. Just be sure you don't exceed the input limits such as "max PV input voltage" and "max short circuit current".

Do some searching on "over paneling".

Adding additional solar charge controllers is a perfectly common way to add more support for more solar. The limiting factor is ensuring that your total charge current from all charge sources doesn't exceed the max recommended charge current of your battery bank.

 

[GFruge]

I just read the spec sheet.

Here’s my current setup:

Growatt 6kw Hybrid Inverter (grid tied)
48v battery charge
120/240v output
6,000 watts rated power
5,000 max PV input

(2) Lifepo4 125aH batteries 51.2v Max
(10) 530 watt panels

 

[rmaddy]

So it's 5000W of max solar, not 6000W. So you are already ever so slightly over paneled at 5300W. Whether you can add another 1060W of solar panels depends on other specs you haven't posted yet (max PV input voltage of the Growatt and the panel's Voc).

But again, if you end up with 6360W of panels you will never get more than 5kW out of them. But you will get the full 5kW far more often.

 

[GFruge]

Max PV charge current 80A
Max PV open circuit 250v

 

[GFruge]

Don’t have vocs on panels.

 

[rmaddy]

The Voc of your panel should be shown on the label on the back of the panel.

 

[timselectric]

Max PV open circuit 250v

That's very low for a grid tied inverter.
What's the model number?
How old is this inverter?

 

[GFruge]

Inverter is only 6 months old.

Growatt, model number SPF 6000T DVM-MPV

The panels are mounted on the roof. I’ll reach out to the guy that sold them to me to give that info

 

[400bird]

Call me whatever you’d like, but I need some clarification.

Hi Steve, lol

Back in September of this past year, we installed a grid tied system to our home. However, I’ve been looking into other alternative ways to generate electricity to store to those unfavorable days. I’ve checked wind and hydro, but it just doesn’t seem to generate enough or not cost effective. With either system, I’d need to add a charge controller to charge the batteries with either.

As others said, a charge controller is very normal. Seems like you're looking at it as a down side and just an expense. But, if you want more power you need to get it into the battery some how.

If you have the possibility, micro hydro is great for your base load. It can provide a nearly constant wattage to support your constant needs.

 

[GFruge]

Hope this makes sense. Panels 49.6v. I have 10 of them

 

[rmaddy]

What is your current panel arrangement? With 10 panels you have either 10S, 5S2P, 2S5P, or 10P. The first two options will damage your Growatt due to excessive voltage assuming the Voc is 49.6V.

 

[GFruge]

For the micro hydro, it’s definitely a possibility for low production. Maybe 300-400 watts max. I have 75’ of drop from 1 site and most likely 100’ from a neighbors site that the overflow flows through my property. Either way, I’d have to invest quite a bit to build a retention and whatever else it would take. On top of that, it would be seasonal. My home is down in Nicaragua. We have about 6 months of rainy season. When it rains, I’m sure I could get 50 gpm or more. Everything would depend on the rain though. During a non rainy day during the rainy season, I would estimate 20 gpm.

 

[GFruge]

No, 400bird made a comment about a micro hydro a few messages up

 

[400bird]

For the micro hydro, it’s definitely a possibility for low production. Maybe 300-400 watts max. I have 75’ of drop from 1 site and most likely 100’ from a neighbors site that the overflow flows through my property. Either way, I’d have to invest quite a bit to build a retention and whatever else it would take. On top of that, it would be seasonal. My home is down in Nicaragua. We have about 6 months of rainy season. When it rains, I’m sure I could get 50 gpm or more. Everything would depend on the rain though. During a non rainy day during the rainy season, I would estimate 20 gpm.

But, when it rains there are clouds? So your solar production is down? It might complement your solar nicely.

Do some research, I don't think you'd need to build much for water retention. Just enough to get water into the pipe at your highest point, then run the hose down to your lowest point so the turbine can dump back into the stream/river.

500 watts * 24 hours = 12kWh
That's something like what a 2kw PV system does in a day depending on the effective sun hours.

 

[GFruge]

I think I may try to micro hydro later. Seems like an interesting project especially since I have decent conditions for one. But for now, I think the additional panels should work.

We have rain still from the tropical storm that passed over us. I’m currently charging the batteries from the grid to last us tonight. Electricity down here is very expensive compared to the US per kwh. Aside from that, it’s a 3rd world country and the grid is not stable at all. Power goes out often. So, my investment serves for 2 reasons.

 

[GFruge]

Panel arrangement is 2S5P

 

[timselectric]

Growatt, model number SPF 6000T DVM-MPV

That's not a grid tied inverter.
It can't export power to the grid.
It's an off grid AIO.

 

[GFruge]

Forgive me for my ignorance. When our batteries discharge, it switches to give us electricity from the grid. I guess I assumed that it meant grid tied. We do not send electricity back to the grid by no means.