As for introductions, evening all. Having read a lot of the posts you have posted, I though to join and to get some advice. Based in CT and currently I have a 'decommission' grid tie system. I'ts been a bit of a journey,  coupled with some ignorance and emotions, as is life.  Not to mention the appropriate levels of loss of love for Eskom and kie.

 

Well, now I have to following question for all of you regarding off-grid.

 

1. The 3.6KVA [or so] limit the council impose per 60A connection, is this only for Grid-Tied confirmed?

2. I'm looking for a good off-grid inverter. If need be, I'l do a manual swop over to grid, and let the inverter then charge the packs, for dark winter days or excessive use. Automatic or manual switch over with relay of some sorts. Daily usage (optimized) is around 20kw, peak to 35kw or say peaks of 7kw pwer hour. This is peaks. A 5kw inverter should be able to do the job, if I put the geyser(s) on relays and pool pumps etc. Thus, what is a recommended off-grid inverter. It will have to limit the max charge or cutoff voltage, to lower or equal to 57.4 volts and lower limit to about 42 to 43.2V. Preferably also adjustable. Would be nice if it can take 2 strings input, but not mandatory. Currently I have 3kw panels in 2 strings. I will expand this as well later. If the inverter could be chained later, that would also be a bonus, or the setup being expanded.

IF anybody are aware of any pitfalls in inverters to be able to charge and supply power from the panels at the same time, could you please mention that for various inverters if you have experience or knowledge?

Budget is always tight, but need to be a good/decent inverter so to speak.

Much appreciated.

Welcome Regalo.

6 minutes ago, Regalo said:

1. The 3.6KVA [or so] limit the council impose per 60A connection, is this only for Grid-Tied confirmed?

2. I'm looking for a good off-grid inverter. If need be, I'l do a manual swop over to grid,

1) 3.5 - and yes, only for grid tied.
2) If you do that, it is a problem. Must not be able to connect at all. Same as if you connect a generator. Unless it is something that no-one is aware of.

Off grid inverter? Victron.
Or if you must, have no choice, you cannot help, then a Axpert. 🙂 

TTT,

 

1. Thanks.

2. When you say 'Same as if you connect a generator', does this mean yes. it can be done? How do people CoC generators?

 

Thanks.

11 minutes ago, Regalo said:

2. When you say 'Same as if you connect a generator', does this mean yes. it can be done? How do people CoC generators?

The generator can never ever meet Eskom, and vice versa, never the twain shall meet. Changeover switch that disconnect everything.

If done properly the Sparkie gives you a CoC for the generator install.

Word has it that if you declare off-grid, with a CoC to prove it, you need to have the same for off-grid solar.

So you cannot legally have the inverter connectable back to Eskom to charge the batteries.

TTT,

 

Thanks for the quick reply. Yes, that is what I was expecting. Never ever meeting, and neither use eskom via the inverter to charge the packs.

I saw in other threads you are quite less romantic about Axperts. I a full off-grid as you explained, should they be able to do the job? Just been looking at Victron, but man, they are expensive. 25K the cheapest so far.

I just don't like it when I buy something and lets say the firmware has a know issue and the manufacturer does not give two toots. So the guys from Aus, Coloumb and co, has to jump in and save the day. Respect to them, but I'm not making Voltronic richer. 

As a UPS, I would suggest Axpert any day!

Victron is there if you want something that has a 5 year warranty,. support when required, parts can be repaired / replaced after 5 years, firmware that gets updated regularly, scalability etc.

And you like plug and forget.

Axpert is much cheaper ... and does not have all of the above ...

But if you are not fussed, DIY handy, then Axpert is a good off-grid inverter. Just study PF ito the firmware you need to upgrade AND most importantly, that the one you get is not a clone.

9 minutes ago, Regalo said:

Never ever meeting, and neither use eskom via the inverter to charge the packs.

I found that 3kva grid tied is much cheaper than off-grid. You save from the moment the sun comes up, to the last watt from the panels.

And you can use a smaller battery bank than if you are off-grid.

3 minutes ago, The Terrible Triplett said:

I found that 3kva grid tied is much cheaper than off-grid. You save from the moment the sun comes up, to the last watt from the panels.

And you can use a smaller battery bank than if you are off-grid.

Agreed. That is what I did the last 5 years. But, can't stomach this crap any more. So, the cost is close now to get over all the red tape, certifications, meters, fixed monthly cost increase etc, and it depends on your DIY level and overall cost. Bottom line, I agree, or use to.

But thanks, the clones is a good point. I will take not of that one.

1 minute ago, Regalo said:

1) ...can't stomach this crap any more.
2) ... red tape,
3) ... certifications,
4) ... meters,
5) ... fixed monthly cost increase

1) It is said to not make a decision on emotion. Must be cold hard facts. Eskom is cheaper - don't throw out the baby with the water. 🙂 
2) What red tape? NRS and SANS is good when 1000's and later a 1 000 000 inverters see the light of day in SA. 
3) NRS certified is in lieu of no SABS certification, so it is good AND you are assured of a solid manufacturer and a good product.
4) What meters? Just need a PAYG meter if you go grid tied. Unless you want to feed back and that we won't do, then you need a bi-directional one.
5) What fixed cost? Unless you want to feed back and that we won't do, there is no extra costs.

1. I've made sort of peace that i wont overcome this till the end of days. But yes.

As for the rest, this is not a solution to Grid tied without feed back which I have considered previously. It should be well worth a consideration then.

So, we are then still limited to the 3.5kw production limit. With my current system, this will be somewhat limited, since my requirements on power has increased by about the size of a granny flat. Also, I might not be able to expand, if I understand the limitation correctly? Without having investigate your option further, is the previous assumption more or less correct? And can one work past it?

..... ps. 

Also thinking that you would still need a decent amount of storage, since quit an amount of power is used at night and early morning. Call it life style choices. Which kinda brings me back to the full circle. I just used the grid in the past.

...ps2.

So, with 3.5kw limit, my history of 4.3 full sun hours per day over the past 5 years, will give me an average of 15.4kw per day. For winter, this would be far below, and about 1/3 to 1/2 half below average annual consumption/demand.

I was thinking of about 7kw of panels. crrent 3kw plus 10 new ones. Which would make the above some close to break even, flattened out per year.

54 minutes ago, Regalo said:

So, with 3.5kw limit, ...
.... I was thinking of about 7kw of panels.

The limit of 3.5kw is on the inverter output into the DB.

You can have as much panels on the roof as you can use - like to power the inverter and recharge the batteries - like say 5kw - there is no limit on that as far as I am aware.

1 hour ago, Regalo said:

, since quit an amount of power is used at night and early morning

you would still need a decent amount of storage

If you are off-grid, you need a decent amount of storage yes - and the panels to recharge them daytime AND you need surplus for rainy days / week.

With grid tied, you don't need a lot of batteries.

Off-grid ONLY works when you are on say a farm with either huge connection cost or are reliant on a generator. Then off-grid makes sense.

In cities, off-grid does not make financial sense - ever. 🙂 

 

Remember, with grid tied, lets say you have a 3kva inverter (2.4kw actual) - if your loads are the whole day 2.4kw per hour, then the inverter feeds that from the panels - if the panels can produce that.

Lets say the load jumps to 10kw, then 2.4kw comes from the inverter, the rest from Eskom. If you are off-grid, you need a 10kw inverter.

The general rule of thumb, most of our loads, if we don't have a pool pumps etc, averages below 1kw. So you want to kill the average loads, not the peaks, and not the evening loads, as evening loads need batteries = more expensive than Eskom per kw/h.

11 hours ago, Regalo said:

Daily usage (optimized) is around 20kw, peak to 35kw or say peaks of 7kw pwer hour

Stock standard hissy fit over units incoming... Is that 20 kilowatt-HOUR ? Kw is a flow rate, so that is like saying my daily water use is 20 liters an hour. Your peak would then be just 7kW, not 7kW per hour. kW per hour would be the second derivative and would indicate the rate of change of energy use (kinda like acceleration in physics) 🙂

So on this topic of how much one can tie, I've often wondered if it might make sense to run a split system. Put a 3.5kw grid-tied unit on the grid side, and run your pool pump and tumble dryer and lawnmower and whatever from that side. Put in a purely off-grid system for the other lower-load stuff, such as lights and television and maybe fridge and freezer and so on, and of course that could be any size. Advantage of a smaller battery at the cost of a second grid-tied inverter.

3 hours ago, plonkster said:

Put a 3.5kw grid-tied unit on the grid side, and run your pool pump and tumble dryer and lawnmower and whatever from that side.

Solis for grid tied operation on the daily loads.

3 hours ago, plonkster said:

Put in a purely off-grid system for the other lower-load stuff, such as lights and television and maybe fridge and freezer and so on, and of course that could be any size. 

Axpert off-grid for always on circuits.

You still are looking at the cost of the batteries going off-grid.

 

Been thinking on this thread. Seems to me that there could be a misunderstanding of the benefits and cost savings of grid tied systems.
AND it made me wonder: So you get a Axpert off-grid setup because Axperts are cheaper right?

Lets take it here: Which ones saves you more, 5kva Axpert off-grid or 3kva Victron grid tied, over 5 years?

Edited May 31, 20197 yr by Guest

1 minute ago, The Terrible Triplett said:

So you get a Axpert off-grid setup because Axperts are cheaper right?

I know there are many people here with Axpert's that are pushing 5 years and more, but just judging by the number of threads where something is broken... something blew up... someone is looking for a repairer... etc. I think you have to ask how long you intend this to last. I still rate the Axpert as a 5-year inverter. Which means that in a ten year period you will buy two of them abd the second one will cost more than the first (due to inflation), so if the 10-year inverter is only 200% of the price, you ought to buy the 10-year inverter. You'd be saving money. I think we're still around the 300% mark though (if you also add in a solar charger), and the rule is that money spent in the future is always worth less than money spent now.

Also remember the Axpert still has the float bug, still needs to get firmware from some enthusiasts down in the way south, still doesn't do decent SOC and needs extras for those too, needs 3rd-party monitoring stuff that's not precisely cheap anymore. I can sort-of buy the argument that it is  good UPS (where the float bug and SOC is not such a big issue), but I cannot quite extend myself towards recommending it as a good solution for any reason other than saving money.

Both,

 

Thanks for the feedback. As a dilettante, I will make a greater effort on the terminology. Seems I've got some planning to do on my setup, but thanks again.

Hi all. I have a 96v 15kw ups/inverter i need a solar charger 96v 100a charge controller. Does anyone know where i can buy this?

@Riaan

I assume it's an online ups I'm not sure about a 96v charge controller but you could also look at a 10kva grid tie inverter and feed the ups with that and let it charge the batteries itself

Morningstar TS-MPPT-60-600V-120 is the only one I could dig up with a little googling. That can apparently handle batteries up to 120V.

I have a newbie question for the forum:

My 48V system loses steam on these cloudy Cape Town days and some mornings I find that one or both inverters have just shut down.

The Victron chargers are very expensive and I was wondering if there was a cheaper option.

What would happen if I connected a 48V power supply to the batteries to "trickle charge" the batteries at night? I am sure that the power supply would "charge" the batteries once they drop below 48V, I am just not so sure what would happen when the voltage is above 48V.

Maybe @plonkster, @Coulomb or one of the masters can set my straight.

Thank you for a great forum.

1 minute ago, Goedman said:

What would happen if I connected a 48V power supply to the batteries to "trickle charge" the batteries at night?

You're better off not letting the battery get so low, by letting the inverter switch over to grid (assuming you're running an Axpert) when the battery runs low. Otherwise, you have losses from the charger, losses from the battery, and losses from the inverter, and you could just supply the loads directly from the grid instead. Cut out the middle men!

If you have the money, of course you could add more battery or solar or both, whatever is short in your system, and it would not "run out of steam" most mornings.

To answer your question as to what would happen when the battery voltage exceeded 48 V, it's probably nothing, until it reaches the "back to battery" voltage (setting 13, again assuming an Axpert). That's likely to be well over 50 V.

6 minutes ago, Coulomb said:

You're better off not letting the battery get so low, by letting the inverter switch over to grid (assuming you're running an Axpert) when the battery runs low.

Sorry, it sounds silly but I don't know what kind of inverters I have. It is called a PowerStar LW (picture attached).

On sunny days my system seems to cope, it is just the cloudy rainy days like today. @plonkster will know because it must be raining by him as well.

24 minutes ago, Goedman said:

My 48V system loses steam on these cloudy Cape Town days and some mornings I find that one or both inverters have just shut down.

What Coulomb said ... 

17 minutes ago, Coulomb said:

You're better off not letting the battery get so low, by letting the inverter switch over to grid

 

Get more batteries and panels to recharge the bigger bank to have +-3 days backup power.
Or if there is no Eskom, a generator that starts once the batts get to a pre-determined SOC as determined by you.

Edited June 21, 20197 yr by Guest