The Battery Thread (Solar / Inverter)

[wingnut771]

With MPPT you don't want to be at the low end or the high end of the range, you want to be in the middle, so to me a 6panel string would be my choice.

Remember that the higher you go with the series strings you will have to start to worry about the voltage rating, I am sure your installer chose stuff that are rated up to a certain voltage and current, your cables, fuses and switches.

You want to modify the installation without having to install new cables and stuff, 8 panels take you over the 300V mark, I am not sure what everything is rated for but I wouldn't want to go too close.

Yeah, but then you're wasting 2 panels. 8 panels is in the middle of the range of the MPPT by my calculations working off the Vmp values. 41.47 x 8 = 331V, way below the max.

 

[TheChamp]

Yeah, but then you're wasting 2 panels.

With his current setup, yes. If all eight panels can work without any issues, sure, I just want him to be aware of the factors that can impact the modifications.

 

[wingnut771]

With his current setup, yes. If all eight panels can work without any issues, sure, I just want him to be aware of the factors that can impact the modifications.

Agreed that the safety systems should be checked to see if they're correctly specced to handle the reconfiguration, but that's an easy fix imho.

 

[wingnut771]

@Crush

Can you post some pics of your setup? That should shed some light on the subject.

 

[AchmatK]

If all the panels are installed in the same location, changing the string configuration should be fairly simple.

I had 4 strings of 7 panels and just got up on the carport and reconfigured the connections underneath the panels.

Now I have 2 strings of 11 panels and one string of 6 panels.

Should be as simple as unclipping 3 of the MC4 connectors at the panels and reconnecting. Remember to first disconnect the strings from the inverter. You don't want to disconnect DC cables with a load on the panels.

 

[gimpex]

That's fantastic yield! How many batteries do you have?

A buddy of mine is getting the same 8 panels installed tomorrow, so that will be a good test to see what he maxes out in terms of generation as we have the exact same panel setup, but with different inverters. His orientation will be fairly similar to mine - NE.

My geyser timers are only going in this week, so once that's done, I should be 80-90% off grid for spring / summer / autumn. Will need 1 more battery to get to 100% I reckon. For winter I'm hoping for a 50% reduction.

I’ve got 2x 5.7kw lithium batteries.

Panels I’ve got 8 on one roof and 8 on another roof , and I can see they produce differently in the early morning and late afternoon due to sun angle.

For geysers I use the 40amp smart switches , forget the name but it was mentioned here a few times , but I believe the cbi astute will do the job too. I like them cause they can be programmed for specific times but if the weather changes or for some other reason you want to override it or start earlier /later it’s possible from your phone. Same switch on pool pump

 

[Colin62]

I had a nice formula for voltage drop but now all I find is in AWGs and feet, I hate those.

I’ve been using this

AC and DC Voltage Drop Calculator AS/NZS 3008

Calculate the AC or DC voltage drop with this Free Online Voltage Drop Calculator. Supports AS/NZS 3008. Includes voltage drop Formulas and Examples.

www.jcalc.net

 

[gimpex]

That's fantastic yield! How many batteries do you have?

A buddy of mine is getting the same 8 panels installed tomorrow, so that will be a good test to see what he maxes out in terms of generation as we have the exact same panel setup, but with different inverters. His orientation will be fairly similar to mine - NE.

My geyser timers are only going in this week, so once that's done, I should be 80-90% off grid for spring / summer / autumn. Will need 1 more battery to get to 100% I reckon. For winter I'm hoping for a 50% reduction.

Regarding winter , my max yieLd was around 65% , just checked now , so I still managed to do the same as summer except that the battery was full later in the afternoon , but net result was the same - full battery when the sun goes down . And winter there are a lot less cloudy days so it averages out.

 

[Crush]

This is what my setup looks like... overall plus DC box. This disconnects under the inverter are for the AC side, and I've got a changeover inside the main board.

Fuses on the DC side should be fine for single string of 8 panels? Either way, I'll get the installer to do the work and to calculate and check that hes happy as well.

On the roof, panels are all in the same area so it will be a simple case of disconnecting and rearranging the MC4 connectors. I'm not too concerned about that. We did the install to account for future expansion and reconfiguration of the strings.

 

[Neuk_]

Question for those with solar panels installed... what peak solar are you getting out of your array? I'm maxing out at around 75% of rated power on the roof, which I dont think is too bad.

I've got 8 x 535w JA solar panels on 2 strings of 4 panels each. It quickly ramps up to around 3.25kw of power and can pretty much stay there from 8h30 till around 15h00 if the load is sufficient or batteries are charging. My panels are NE-facing with a 30 degree angle bracket with a slight east tilt as well because of the roof leaning that way. Not ideal but not bad.

On the battery side, I think anyone buying lead acid is making a HUGE mistake. Yes, LiFePO4 is a huge investment, but cycling them overnight is where I'm starting to claw back money from my investment. I have 2 of the PylonTech 3.5kwh batteries which are rated at 6000 cycles at 95% DoD. I run them down to 15% each night and that seems to work well. I've had two sets of lead acids on a purely backup system before and they just dont work well and are VERY hard to monitor. With the Pylons sorting themselves out, life is much easier.

We have seen peaks at 105% of theoretical maximum PV generation capability but for very short periods as our loads are very low, we have two strings of five Canadian Solar 360w PV panels, one facing East and the other West.

 

[Tariqe]

On a sunny day I can easily get about 90% on my Sunsynk

 

[Speedster]

This is what my setup looks like... overall plus DC box. This disconnects under the inverter are for the AC side, and I've got a changeover inside the main board.

Fuses on the DC side should be fine for single string of 8 panels? Either way, I'll get the installer to do the work and to calculate and check that hes happy as well.

On the roof, panels are all in the same area so it will be a simple case of disconnecting and rearranging the MC4 connectors. I'm not too concerned about that. We did the install to account for future expansion and reconfiguration of the strings.

Very nice install. What system did you use for the panel mounts?

 

[Crush]

Very nice install. What system did you use for the panel mounts?

Thanks... my installer has a supplier that makes aluminium angle brackets to create the required pitch.

So it's just normal clamps on IBR roofing with angle brackets on those and beams going across. You can see it better in this pic...

 

[johnjm]

This is what my setup looks like... overall plus DC box. This disconnects under the inverter are for the AC side, and I've got a changeover inside the main board.

Fuses on the DC side should be fine for single string of 8 panels? Either way, I'll get the installer to do the work and to calculate and check that hes happy as well.

On the roof, panels are all in the same area so it will be a simple case of disconnecting and rearranging the MC4 connectors. I'm not too concerned about that. We did the install to account for future expansion and reconfiguration of the strings.

It would be better to match the panel voltage to have better efficiency. I’m not sure who said it above but the Voc needs to be in the upper range of the MPPT to be more efficient, not in the middle.

My little system is small and simple, but I matched It to 80% of the MPPTs max voltage for better efficiency.

I’m currently being loadshed and it’s operating at over 90% of the rated PV power of 650w throughout so far, 90 min in.

 

[johnjm]

This is what my setup looks like... overall plus DC box. This disconnects under the inverter are for the AC side, and I've got a changeover inside the main board.

Fuses on the DC side should be fine for single string of 8 panels? Either way, I'll get the installer to do the work and to calculate and check that hes happy as well.

On the roof, panels are all in the same area so it will be a simple case of disconnecting and rearranging the MC4 connectors. I'm not too concerned about that. We did the install to account for future expansion and reconfiguration of the strings.

It would be better to match the panel voltage to have better efficiency. I’m not sure who said it above but the Voc needs to be in the upper range of the MPPT to be more efficient, not in the middle.

My little system is small and simple, but I matched It to 80% of the MPPTs max voltage for better efficiency.

I’m currently being loadshed and it’s operating at over 90% of the rated PV power of 650w throughout so far, 90 min in.

 

[Crush]

Thanks! That's helpful info. My installer just came past to tidy up some cabling that I wasnt happy with which was hidden behind my geyser enclosure. And also to install my timer on the DB for the heat pump. We quickly ran through the calcs for a single string and hes happy that we will be ok with a single string running at approx 370v.

Will maybe try that out in a months time and will report back. For now I'm producing more than I can use or store during the day so it's not critical. But once I another battery, it would he useful to have say 10% more power being generated. I didn't think efficiency drops would be significant enough to reduce peak production by say 10-25%. I would have thought it would be in the order of the last 3-5%.

Hope the 25% drop off is not related to something else as well.

 

[RedViking]

Too lazy to search this thread. Looking for replacement batteries that will last longer. Previously had this:

Enertec (Energizer) 105AH Deep Cycle Battery - 12 Volt (200-250 cycles) - GeeWiz

Enertec (Energizer) 105AH Deep Cycle Battery - 12 Volt (200-250 cycles) for sale online at the Best Prices! Door to Door and Overnight Delivery

www.geewiz.co.za

Have anyone used these or recommend something better in the same price range?
(I will need two though to get 24V)

Vision 200Ah AGM Deep Cycle 12V Z series (6FM200Z-X)

200Ah AGM Deep Cycle 12V Z series (6FM200Z-X)

www.geewiz.co.za

or

Batteries

Buy Batteries online at the Best Prices! Door to Door and Overnight Delivery. Voted the best online store in SA. View Here

www.geewiz.co.za

 

[RedViking]

This is what my setup looks like... overall plus DC box. This disconnects under the inverter are for the AC side, and I've got a changeover inside the main board.

Fuses on the DC side should be fine for single string of 8 panels? Either way, I'll get the installer to do the work and to calculate and check that hes happy as well.

On the roof, panels are all in the same area so it will be a simple case of disconnecting and rearranging the MC4 connectors. I'm not too concerned about that. We did the install to account for future expansion and reconfiguration of the strings.

Beautiful.

 

[Neuk_]

Too lazy to search this thread. Looking for replacement batteries that will last longer. Previously had this:

Enertec (Energizer) 105AH Deep Cycle Battery - 12 Volt (200-250 cycles) - GeeWiz

Enertec (Energizer) 105AH Deep Cycle Battery - 12 Volt (200-250 cycles) for sale online at the Best Prices! Door to Door and Overnight Delivery

www.geewiz.co.za

Have anyone used these or recommend something better in the same price range?
(I will need two though to get 24V)

Vision 200Ah AGM Deep Cycle 12V Z series (6FM200Z-X)

200Ah AGM Deep Cycle 12V Z series (6FM200Z-X)

www.geewiz.co.za

or

Batteries

Buy Batteries online at the Best Prices! Door to Door and Overnight Delivery. Voted the best online store in SA. View Here

www.geewiz.co.za

I saw some monster 390Ah Enertec batteries when I was at their Jhb office/DC a few weeks back so I am sure they have some options for you.

 

[RedViking]

I saw some monster 390Ah Enertec batteries when I was at their Jhb office/DC a few weeks back so I am sure they have some options for you.

I don't want Enertec again.

They recommend the vision AGM on their website for more cycles.