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Adding additional Lithium Batteries to a Solar System after a few years

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I have an existing installation which consists of a Deye 8kw Inverter, 24 Canadian panels (totalling 10360w) and 2 x Dyness 5200 (5.2Kwh) batteries. My intention is to add 2 x additional Dyness 5200 batteries, in a staggered manner, over the next few years.

In a conversation with a colleague, he was informed that adding "new” batteries to an old installation (to an existing bank of batteries) will degrade the “new” batteries.

Is this correct?

5 hours ago, Marcodp said:

I have an existing installation which consists of a Deye 8kw Inverter, 24 Canadian panels (totalling 10360w) and 2 x Dyness 5200 (5.2Kwh) batteries. My intention is to add 2 x additional Dyness 5200 batteries, in a staggered manner, over the next few years.

In a conversation with a colleague, he was informed that adding "new” batteries to an old installation (to an existing bank of batteries) will degrade the “new” batteries.

Is this correct?

No, not correct.

5 hours ago, Marcodp said:

I have an existing installation which consists of a Deye 8kw Inverter, 24 Canadian panels (totalling 10360w) and 2 x Dyness 5200 (5.2Kwh) batteries. My intention is to add 2 x additional Dyness 5200 batteries, in a staggered manner, over the next few years.

In a conversation with a colleague, he was informed that adding "new” batteries to an old installation (to an existing bank of batteries) will degrade the “new” batteries.

Is this correct?

Definitely not correct :) You can add new batteries to old, you can add bigger batteries (AH) you can mix and match as you like as long as the chemistry and cell numbers match.

6 hours ago, Marcodp said:

I have an existing installation which consists of a Deye 8kw Inverter, 24 Canadian panels (totalling 10360w) and 2 x Dyness 5200 (5.2Kwh) batteries. My intention is to add 2 x additional Dyness 5200 batteries, in a staggered manner, over the next few years.

In a conversation with a colleague, he was informed that adding "new” batteries to an old installation (to an existing bank of batteries) will degrade the “new” batteries.

Is this correct?

You can add new batteries. If adding in parallel and same battery it will work well. Especially if within 2 years. Over time the internal resistance of lithium batteries do increase, so the new battery will work a bit harder, but over time they will equalize. In series it is a bit more tricky, a good battery balancer can then help with that.

1 hour ago, Scorp007 said:

This remains the best plan of action. Too many tales/urban legends floating around. 

@Scorp007 I’ve found that in some cases it’s scare mongering an end user to sell their existing batteries at rock bottom prices so the installer can they resell them to someone else either “as new/almost new” & maximise profits. 

3 minutes ago, Moffat said:

@Scorp007 I’ve found that in some cases it’s scare mongering an end user to sell their existing batteries at rock bottom prices so the installer can they resell them to someone else either “as new/almost new” & maximise profits. 

Always better for the seller to sell 3-4 new ones and buy the old ones for peanuts as you say. 

But amazing how bad news spreads and sells. 

  • 4 weeks later...
On 2023/12/21 at 10:07 AM, Marcodp said:

I have an existing installation which consists of a Deye 8kw Inverter, 24 Canadian panels (totalling 10360w) and 2 x Dyness 5200 (5.2Kwh) batteries. My intention is to add 2 x additional Dyness 5200 batteries, in a staggered manner, over the next few years.

In a conversation with a colleague, he was informed that adding "new” batteries to an old installation (to an existing bank of batteries) will degrade the “new” batteries.

Is this correct?

This system is incredible panelwise. Looks like you have max'd the inverter mppts. How is the solar generation look like, peak and offpeak?

 

And much do you generate per day?

  • Author

@Jakac, yes I have pretty much max'd the MPPT's - the Inverter can take max 10400w and I am at 10360w. The Voltage however is the key metric, and I am at slightly below the 500v inverter limit, so in theory I could add additional panels as it is unlikely, I would get near the actual max wattage.

SolarPanleConfig.thumb.jpg.f20ccc29cce85bae10acbee1722815b0.jpg

From a generation viewpoint, consider I only generate what I use, so the max I have actually generated on any 1 day was around 45Kwh, with a daily average of around 35 kWh and just over 1 MWh in the month.

I am in Cape Town, so generally start producing at 6am in summer and generate until around 8pm, with peak between 12pm - 1pm.

Winter will be a lot lower, and with the panels only being installed recently, time will tell what the winter months will look like.

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