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Starting from scratch


Czauto

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Good morning guys (and maybe some gals),

As some might know, I've sold my complete system a while ago and am planning to upgrade and have the chance to start from scratch.

What I have:

Municipal grid supply through prepaid meter,

7700va Generator gathering dust,

Enough north facing roofspace for at least 30 x 250w solar panels.

 

Factors that need to be reasoned with upgrade:

Batteries are k@k expensive,

I can source solar panels at +-R5/W,

I'm in the process of rewiring my house so splitting my DB won't be extra cost (or much anyway),

I've already got rid of all big electrical consumers (Stove, geyser, heaters, etc) and gone LPG on most,

All lights are already LED and appliances Energy efficient ones (A+++)

 

So, after much planning and research on this wonderful forum of ours I've concluded to the following options:

Option1:

Split DB with all essential loads on a seperate circuit,

Axpert 3kva 24v inverter to handle essential loads (MPPT not used, Batteries charged from grid)

Grid tied inverter handling everything, including charging batteries through Axpert and feeding excess power back into grid,

2 x 105Ah cheapie deep/high cycle batteries for short term backup for the axpert,

7700VA generator started automatically when batteries needs charging and Grid supply is unavailable,

at least 5Kwp solar array.

 

Option 2:

Infinisolar 4Kw super inverter - Offgrid mode,

2 x Pylontech 2.4Kwh batteries,

Max solar array Inverter MPPT can handle,

Genny for backup,

 

Option 3:

Infinisolar 4Kw Super inverter - Grid-tie mode,

4 x cheapie 105Ah high/deep cycle batteries (only for limited backup and inverter buffer purposes),

Max PV array MPPT can handle,

Generator for backup,

 

Input or any other suggestions on this decision will we greatly appreciated. I want this system to last at least 10 - 15 years before even having to think about upgrading again and obviously keeping in mind maximum savings. 

I've been back on Eskom for almost two months with only a small backup system for lights so I need to make a decision fast!

Greeting from the Dry Karoo.

 

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Whatever inverter you do decide on to grid tie, make sure it is on the CoCT list. You may or may not have the municipality focusing on it yet, but NERSA will get them to focus one day.

Maximum savings in MY opinion is grid tie, batteries for a short period as you planned, gennie because there is no solar and batts are small.
Option 1: Solis for the entire home and Axpert to sort the UPS part with gennie as backup.
Option 2: Goodwe - others can go into more detail.
Option 3: Multigrid 3000, has all you need ito grid tied and select circuits to power and generator start and it will last 10-15 years - once you have tuned it to your particular needs.

For 10-15 years, I would expect backup and support, if I need it.

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29 minutes ago, Czauto said:

Axpert 3kva 24v inverter to handle essential loads (MPPT not used, Batteries charged from grid)

You have the chance to start over and you want go go back here!? :-P

A bit more seriously though, why did you not consider a different brand inverter? If you have something against blue, why not a Goodwe for example?

32 minutes ago, Czauto said:

I want this system to last at least 10 - 15 years before even having to think about upgrading again and obviously keeping in mind maximum savings. 

Then don't fit a Voltronic, or at least not an axpert. I'm going to get some flack for this maybe, but if that's the time span then get something with at least a 5 year warranty.

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1 hour ago, Antony said:

But you still have the hairdryers? :D

That is a NEED! And anyone who tries to classify that as a WANT, knows the consequences are life threatening, dire at best. :D

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I'm thinking of a slightly diffrent suggestion. A simple dumb inverter or ups connected off grid. That's it done keep it off grid no fancy stuff. Then a seperate PV charge controller , an appropiatly sized mains powered battery charger for low SOC days,   and batteries to give you at least 1 day autonomy . When that's not enough fire up your generator.  Having cheaper/more cost effective  individual components, if it doesn't last the 20 years it won't break the bank again to fix the issue.

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Thanks for the input. Exactly my idea with a cheap inverter for basic needs. That's why I'm looking at a 24v Axpert 3Kva. I can get these for as low as R3500. This is perfect to use as UPS. Pure sinewave, built in charger, built in 1500W MPPT (should I decide to put a solar array on it) and hey, if it only lasts 5 years so what, At least I still have an arm and a leg to buy a new one then. Throw 2 x 105Ah high cycle batteries (FMF100's or similar) into the mix and I've got a UPS system for less than R7k. Remember this part I can always upgrade again in future, my main concern is then to generate enough electricity to save and at least break even with monthly grid connection costs. Now I know I was completely against grid-tied systems at first but a 5Kwp solar array means absolutely nothing if you cannot store generated energy. Batteries to store eg. 7.2Kwh will cost close to R45k. With that amount i can buy a 8Kwp solar array and use the Grid for storage. We've had very little outages for the last 2 years so my backup part of the system has gone down in my priority list. I do have the genny available for those one or two times a year we "might" have a power outage so i really cannot see why I should take the risk of having expensive batteries working their arse off and which have to be replaced again after, optimistically , 10 years or so. If I did not have grid power, by all means, Pylontech it would be, but with a trustworthy Grid supply (for now anyway) I am really looking in another direction.....

First Prize would be a full Victron off grid system but i simply cannot afford R200k for a solar system and have a ROI of 30 years. I love all of you skepticism and input so please don't stop. I haven't ordered anything yet:D 

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I would go with a hybrid GTI. Yes battery storage at the moment is more expensive than Eskom, but this will soon change. In addition there is another trend taking place in the industrialized world and I think will also come to SA. The power producers/distributers are offering the customers very attractive feed in tariffs whenever they are short of power. This is usually the case in the early morning and late afternoon peak consumption period. To be able to take advantage of this opportunity you need batteries. (Or an electric car 😁).

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21 hours ago, Czauto said:

... full Victron off grid system but i simply cannot afford R200k

Bleh, they must sell me what they smoke, or I'll call the cops on them ... R200k for a off-grid / grid tied legal 24v system ... pffft!.

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