Saturday at home, installing an inverter

[AndyD]

Well we recently went through Stage 6 load shedding....thanks Eskom. In a 48 hour period we had 19 hours without power, six outages in total. Two of the outages were 4.5 hours long and four of the outages were 2.5 hours long.

The inverter managed to handle but the batteries were almost hitting their depth of cycle limit on the second day, it was so close I got a battery safety alarm sounding for the first time ever. The problem wasn't the capacity of the batteries as such, it was that they weren't getting fully charged between load shedding events. If stage 6 shedding had continued for a third day the system would have shut down completely on it's battery protection depth of cycle settings.

Unfortunately adding batteries won't help for this scenario because charge rate was the limiting factor so I'm just going to have to hope we don't get more than 2 days of stage 6 load shedding in future. I guess trying to look on the bright side I now have a better understanding of my back-up system limitations.

[SeanM]

Hi Andy

The only suggestion would be solar panels to assist in the charing.

[Justloadit]

The cost of Lithium is dropping.
A supplier of mine has brought in a in a number of cells to make up battery packs.
He is currently offering me a 72A Lithium at a very reasonable cost, probably double the cost of an equivalent 100A Lead Acid, don't want to say here as it may be a special price to me
You may be/should give him a call Mark @ SJ Andrews, not sure if he is still open due to the holiday season.

Please note that Lithium batteries are not direct replacement for Lead Acid batteries. For safety and prevention of fires, Chargers must match the battery specifications

[AndyD]

Thanks for the suggestions everyone.

Unfortunately solar panels won't help decrease the battery charging times with my inverter. It can't use a mix of both solar and eskom power simultaneously, only one or the other. The Axpert inverter also has very specific PV string voltage requirements. A few panels might assist by supplying some power during the actual load shedding period if it was in daylight hours but for me they're not a finantially viable option with this system as it stands, installing solar panels would only be viable if I replaced my inverter with a better one with a view to feeding surplus back in for the FIT.

Thanks also for the contact but same problem with lithium batteries... compatibility issues.

When I installed this system I was under no illusions about it's capabilities or lack thereof. It was a very low budget system and at that price point I accepted the limitations it had when it came to possibilities for future expansion or redesign. I resigned myself from day one that it was going to do the job I needed it to but it was never going to be a stepping stone toward anything more extensive such as going completely or even partially off-grid with PV and it wasn't going to be very scaleable if my requirements changed much outside the original design brief.

I'm not stressed and I'm by no means disappointed, to be honest I'm actually very impressed it worked flawlessly through the 2 days of stage 6 shedding with surrounding days of stage 4 and stage 2, especially as it's almost 4 years old now. I'll probably like for like replace the deep cycle lead acid batteries when they reach their end of life but apart from that I'm just going to use it as it was originally intended and not over-spend or throw good money at it by trying to make it something it was never intended to be.

[Justloadit]

Unfortunately solar panels won't help decrease the battery charging times with my inverter. It can't use a mix of both solar and eskom power simultaneously, only one or the other. The Axpert inverter also has very specific PV string voltage requirements. A few panels might assist by supplying some power during the actual load shedding period if it was in daylight hours but for me they're not a finantially viable option with this system as it stands, installing solar panels would only be viable if I replaced my inverter with a better one with a view to feeding surplus back in for the FIT.

You can still have solar panels into a MPPT charger connected to the batteries, separate from the AXPERT, and charge your batteries during the day, with out affecting the current connection. The AXPERT would think that the batteries are charged because it would not draw current from the AXPERT, and the Voltage would be higher than what the AXPERT is expecting, and would not use ESKOM power during the day. If the batteries require charging at night, and ESKOM is available, then it would use mains to charge.

Thanks also for the contact but same problem with lithium batteries... compatibility issues.

I have had an idea in my mind for some time now, and wondering if there is a market for it.
What if I supplied you a battery which is Lithium, but would behave as a Lead acid battery, which means that you could replace current lead acid battery pack with a Lithium pack which would appear to the AXPERT inverter as lead acid, but have the characteristics of Lithium?

[ians]

Found this interesting... could this be why they offer a reduction in price if you hand in your old battery... At Ra over R2000 a replacement battery for your backup system... might be worn looking into this method.

https://www.youtube.com/watch?v=TYXx70MqJ-0

[EyeGod]

Hi all,

First post here, just doing some research, and since this thread has seen a lot of activity, I hoped it was the right place to ask:

I'm currently researching residential inverter installations in Cape Town, can anyone suggest someone?

I’m basically looking for a one stop shop and solution, so I would appreciate any advice you could offer.

Thanks in advance!

[SeanM]

Greetings

I do inverter installations in the Cape Town Area if you are interested you may contact me and I will gladly come and see you and advise.

[EyeGod]

Greetings

I do inverter installations in the Cape Town Area if you are interested you may contact me and I will gladly come and see you and advise.

Hi there!

I just sent you a PM; thanks!

[blackknight72]

LEAD CARBON BATTERY VS TROJANS

Hi Andy,

I installed a system based inspired by your write up in Feb 2015 with very similar specs using Axpert 3KV inverter and 4x Trojan T125s. As in your case the use was very minimal as ESKOM almost completely withdrew load shedding in East London. I find the system currently weak with regard to the expectations.I must confess that battery maintenance was poor as I checked the battery water levels only once that too after three years. The inverter is connected to the refrigerator and microwave in addition to the lights. Now with the refrigerator working it will be alive only for an hour or less but with minimal lights and fans it can do some 3 hours.Hence i am thinking of replacing the batteries. What is your opinion with regard to lead carbon vs existing trojan t 125s. Price wise i see no difference . Appreciate your input.

Anyone with experience with lead carbon battery is welcome to share their view. Thanking in advance.

[idian makatu]

Hi AndyD. I am having constant loadshadding at mi area. I want to know how can I select the solar system for my house , , to supply tv and lights Nd a fridge if possible. I want to know the size of panel can get , the battery, inverter , controller.?

[AndyD]

Sizing and specifying a solar system is something that needs a site visit to establish the load profile, where panels could be mounted and how efficient they're going to be with your roof angle and shading etc. You need to find someone in your area that has lots of experience in solar installations because there's no 'one size fits all' solution and many mistakes that can be made when designing these systems which usually work out very expensive. For that reason I'd strongly suggest you at least get professional advice before spending your money.

Most respectable companies will visit your house, give you good advice and do a survey and quotation for free.

Can I ask why you want a solar system rather than just a basic battery/inverter system that just charges from Eskom power? Also out of interest what kind of budget are you working with?

[AndyD]

This thread is a blast from the past. 6 years on and we're still getting load shedding.....sigh.

Well a quick update. The inverter system is still exactly as I installed it, I haven't added or subtracted anything and everything still works fine.....almost.

There was one issue with a hot termination at the battery fuse holder. Luckily I smelled the hot insulation before any substantial damage occurred and I just had to cut the old lug off and crimp on a new one. There was also one string of the 12v back-up lights stopped working which turned out to be a cable that got pulled loose whilst the painters were busy in the vicinity. Apart from those minor niggles the system has performed admirably.

My present day issue is that the lead acid batteries are now at the stage where they no longer hold sufficient charge to cover a two hour load shedding. I was a bit disappointed but after looking at the date I started this thread and realising to my surprise that 6 years has gone by I guess it's to be expected.

I toyed with the idea of replacing the batteries with lithium ion but the price is still somewhat prohibitive at around R30K for decent batteries with a good built-in management system. I'm getting quoted just under R2K for a 235AH 6V deep cycle gel battery which works out to just over R9K for the set.

[blackknight72]

Hello Andy, Good to hear from you!

I built my system around your input around the same time. We hardly had frequent power cuts over the last 5 years and the system was largely unused but whenever it was needed it did a fantastic job. I changed my batteries a couple of months back. This time I went with Trojan T125 Spre 255AH costing R12000 for four. From what I remember your system is also an Axpert 3KW MKS plus. Can you advise if it is possible to add one more of the same inverter to the existing one to facilitate load management?

[AndyD]

Hello Andy, Good to hear from you!

I built my system around your input around the same time. We hardly had frequent power cuts over the last 5 years and the system was largely unused but whenever it was needed it did a fantastic job. I changed my batteries a couple of months back. This time I went with Trojan T125 Spre 255AH costing R12000 for four. From what I remember your system is also an Axpert 3KW MKS plus. Can you advise if it is possible to add one more of the same inverter to the existing one to facilitate load management?

Hi Blackknight, glad the thread was useful to you and it's good to hear your inverter served you well even though it wasn't needed a lot of the time. Unfortunately the old MKS Axpert inverters can't be paralleled together to run as one larger inverter like some of the newer models can.