I have a solar system with 6 X Sunpower monocrystalline 327 watt panels, an Axpert 5 KVA inverter and 4 X 230 Ah Excis batteries. The solar power is wired to plugs and lights only, not the oven or hot plates. Hot water comes from a 16 vac tube system. ( I also store 21000 liters of water, as our local supply is full of sodium, calcium and magnesium salts). The installation is remote from the house, with the panels on a frame above a small solar hut which contains the electrics, the panels are almost due North facing.

I realize now that the system has been running for about 3 months that I should have doubled the battery bank. I have a 25 year old large fridge- freezer which runs too often in hot weather, which is the main 'electrical' culprit. A new A+ fridge freezer would cost about the same as four new batteries: but perhaps I bought the wrong batteries initially as these are high cycle as opposed to deep cycle. I note that the forum's batteries of choice are Trojans. What sort of life can I expect from my current battery bank, is it too late to add 4 new Excis batteries, or should I just continue as I am doing now and switch back to Eskom power as the light fades, so that my batteries remain nearly fully charged?

I have set the Axpert to 50 V on setting 12 ( back to utility source on sbu), but it doesn't seem to work.

Any advice would be welcome, bearing in mind that I am not very electrically technical.

Hi Topman,

Welcome to the forum.

Yes, you are right, the maintenance free Excis batteries are leisure batteries, good for UPS use, weekend camp once in a while, not for daily use on a solar system.

Yes, you are right, the fridge is a HUGE problem that you can overcome with more batteries, or less batteries and a new A++ (not A+) fridge.  But the law of Transvaal is applicable. 

If you drain them past 50%, maybe 7-12 months ... and one will be dead. Do not add more of them. 

If you can tell us the load you want powered and for how long, we can help you work out the bank you need to power it, and to re-charge it.

Re. the Axpert settings, others will be here shortly to assist you.

Hi Tropman

Welcome

1 hour ago, Tropman said:

I have set the Axpert to 50 V on setting 12 ( back to utility source on sbu), but it doesn't seem to work.

 

Program 1 = SBU

Program 12 = 50V

Program 13 =?

So is the unit staying on battery/solar when battery voltage is below 50V?

Hi Chris,

Thank you for your prompt response, yes the unit does not switch off when the voltage drops below 50 V.

setting 13 is at 54 V

TTT has indicated that Excis 230's are not suitable for solar work: I see that they are advertised as 'solar batteries' and I was advised that they were OK. Unfortunately I was not aware of the forum when I bought them. However to make the best of a bad job I will continue with them and try to keep the DOD at less than 20%. Perhaps if Eskom don't lose the plot completely they will still give a reasonable life.

Hold on ... I could have made a incorrect assumption. 

Excis has a few types, the most common being sold as 'deep cycle' are the 100ah maintenance free Excis batteries, which was what I assumed you where sold.

Now IF you have these ones: http://www.battery.co.za/wp-content/uploads/2014/07/Excis-230-Only-April-2012.pdf

Sealed batteries never need water, yet they can vent a bit and when you charge them with solar, they can vent a bit more and over time, require water. If you cannot add water, you are going to have a shorter life span than the ones where you can add water.

MY personal opinion, supported by my battery supplier as they sell similar ones, are that they are NOT deep cycle for you cannot add water.

I sold 200ah, similar as the Excis ones, for UPS'es, instead of 4 x 100ah - 24v (more cable and all that), we sold 2 x 200ah - 24v.

Excis batteries are around 600 cycles to 50% DoD. so if you treat them well you should get 18 months to 2 years out of them.

Fridge and Freezer wise. Things to remember, the rating is related to the size a as well, so a small B-rated appliance might use less than a larger A-rated appliance. I have an A++ rated Bosch fridge (they cost around 10k now) and a 210-liter A-rated Defy freezer. Both use around 1kwh a day.  Moral: part of the story is to NOT have a 330 liter unit when 210 will do, especially for us city folk who don't have to freeze a whole cow along with the vegies.

I can really recommend the Bosch KSV36VL30. It usually retails for less than the fancier LG and Samsung models. The review that convinced me (and I agree) was on amazon.de, here, but you need to read German. It's a glowing review and one I found to be true:

http://www.amazon.de/gp/customer-reviews/R3NS5XF13Y7XIV/

 

2 hours ago, Tropman said:

However to make the best of a bad job I will continue with them and try to keep the DOD at less than 20%. Perhaps if Eskom don't lose the plot completely they will still give a reasonable life.

YES!!! VERY good plan. Here we have a few ways to make your inverter switch back to Eskom, based on say 20%DOD to save the batteries.

When they are done, THEN you get the real ones.

EDIT: After having learned a LOT about batteries and keeping them happy.

Which battery do you recommend

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2 hours ago, Tropman said:

 

Thank you for your prompt response, yes the unit does not switch off when the voltage drops below 50 V.

setting 13 is at 54 V

That is strange. If you change program 1 to UTI does the inverter change to grid. Easiest way to see is the left most LED - flashes whilst in battery/solar mode and permanently on when grid is on.

 

I have the same fridge as Plonky - very good unit.

31 minutes ago, Manie said:

Which battery do you recommend

I prefer Trojans.

I also bought a Bosch fridge, after Plonsters recommendations on the forum. Similar model, got it for a bargain at R6999.00 on a one day special.

Thanks TT

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