Need help in setting up a system.

[Farmer]

I am a new member and enjoy the forum a lot.While seeking for the right advice I came across this forum and trust that I shall find it.I am off grid and use a 14 kw generator to supply power for my and workers houses and pump water for 2.5 hours every night.at approx 3 lit of  diesel/hour. In time I will drop,the genie but meanwhile I am in need of a system that can supply me with 5000 w per day and peak of 1500 w.which can double later.At the moment I am looking at a Sunniva 3.2 kw  48V hybrid inverter.Keep in mind that the genie runs for 2.5 h every day and can help with the charging.How many batt and panels should I use? Verskoon maar die engels ek is regtig n boer!

[Guest]

Farmer, welcome to the forum.
Boer, welkom op die forum. Hier is hele paar Afrikaanse mense. 

Yes, we can help. 

5000w I take it you mean 1000w for 5 hours with peaks of 1500w?

[DeepBass9]

I use this with my gennie, works very well 6kVA, 48V : http://www.jsmpower.co.za/manuals/6k-VA-48V-Inverter-Charger-User-Manual.html

[Farmer]

23 hours ago, Farmer said:

I am a new member and enjoy the forum a lot.While seeking for the right advice I came across this forum and trust that I shall find it.I am off grid and use a 14 kw generator to supply power for my and workers houses and pump water for 2.5 hours every night.at approx 3 lit of  diesel/hour. In time I will drop,the genie but meanwhile I am in need of a system that can supply me with 5000 w per day and peak of 1500 w.which can double later.At the moment I am looking at a Sunniva 3.2 kw  48V hybrid inverter.Keep in mind that the genie runs for 2.5 h every day and can help with the charging.How many batt and panels should I use? Verskoon maar die engels ek is regtig n boer!

Dankie Triplett...well during the time the genie is not running , I need to charge the batt,use the freezer (24h)the washing machine and at night after the genie is off uses lights untill bedtime.During the day the freezer and washing machine( 800 w) should run off the panels and then switch to the genie and then to the batteries.The 5000 is the total watt hours per day and the 1500 the peak.

[Guest]

Fridge and Lights you can run 24/7 off grid. Gennie as back for them as and when. For this you need a small inverter.

Adding a washing machine, the inverter needs to be bigger. So to play it save, as you say, maybe a 3000w inverter, not va, w.

48v is what you want, and my preferred 24v system in you go 24/7 off grid, you need same amount of batts.

If you can pinpoint the loads:
Washing machine on at Xwatts for Y hours.
Xwatts of light on for Y hours

We could calculate the load, batteries needed with 2 days backup and how many panels.

Then you can increase the panels and use more power daytime.

Let me have the numbers.

[Farmer]

Hi Triplett,washing machine use 360 w fir 2 hours a day  and lights 10*15w for 3 h per day.Thanks.

[Guest]

Using 48v, to avert another derailment , you need this for just the lights if you use the washing machine daytime only.

 

[Guest]

Me, I would have gone 24v, and save the cost of 4 batts.

Both 48v en 24v are based on 20% DOD with 2 days backup, so you are using about 10% per day, so it will take days to get down to could run the batts down to 50% DOD.

 

[viper_za]

3 hours ago, The Terrible Triplett said:

Me, I would have gone 24v, and save the cost of 4 batts.

Both 48v en 24v are based on 20% DOD with 2 days backup, so you are using about 10% per day, so it will take days to get down to could run the batts down to 50% DOD.

Again this 
Now look at this using your examples again

48V look at required bank

24V look at required

Only true if he uses the same batts in 24v or 48v but to be the same the 48v needs smaller batts (being cheeper), making the difference between 8 smaller Ah batts for 48v and 4 bigger Ah batts for 24v not that big a difference in price

[Mark]

Any chance you guys can upload the sheet used above.  I can't find it on the site referenced.:  https://electricalnotes.wordpress.com/

Thanks

Mark

[Guest]

YES!!!

The point I am bringing across, know your load, know your needs and ensure you have reserves for there is a very fine line where it makes less sense to go 48v, or even 24v, if 12/24/48v banks all will last +-10 years, yet at 24v 1/2 or a even 12v 1/4 of the cost of a 48v bank IF you get the right batts to last 10 years at 20% DOD and 2 days backup.

See below the numbers for say 6v or 12v 100ah batts 48v, deep cycle ones, this is the smallest batts you can go with 20% DOD and 2 days backup, and probably the cheapest option. Less batts = less worries.

[Guest]

26 minutes ago, Mark said:

Any chance you guys can upload the sheet used above.  I can't find it on the site referenced.:  https://electricalnotes.wordpress.com/

I have uploaded them before.

One is to just calc just the batteries. Other one is to calcs panels to re-charge the batts also. NOTE: The panels are just to recharge the batts, not power a load also, add more panels for that.

Master - Battery size Calculator (22.8.12).xlsx

Master - Off-Grid - Solar Panel-Design1.1.15.xlsx

EDIT: You are not going to like the answers the calcs give. 

[viper_za]

28 minutes ago, The Terrible Triplett said:

very fine line where it makes less sense to go 48v, or even 24v, if 12/24/48v banks all will last +-10 years, yet at 24v 1/2 or a even 12v 1/4 of the cost of a 48v bank IF you get the right batts to last 10 years at 20% DOD and 2 days backup.

The fine line is in the inverters and charge controllers (battery balancers etc) not in the the storage capability of the batterry bank. You need the same kWh to use the same 20% DOD and 2 days backup doesn't matter what voltage system you run...

[Guest]

1 minute ago, viper_za said:

You need the same kWh to use the same 20% DOD and 2 days backup doesn't matter what voltage system you run...

Ditto. 

And the smaller the system, the more affordable it becomes, if you can power your loads with spikes.

Saw a 12v 5000VA Multiplus the other day ... can handle peaks with ease daytime and the small loads on 12v 24/7, so you go 2v 1849ah batts. 

Just have NO idea how to charge a 12v 1849ah bank using a solar controller - closest I can get is 100a charge current. 

[___]

1 hour ago, viper_za said:

Again this 

I'm the other guy here with a 24V system and I'm jealous of the low currents you 48 Volters have to deal with. You can like literally get away with those horrible 105Ah batteries in a pinch and get some decent power out of them :-) As I said it beforem the 24V question is really "Can I get away with it?", and once you start speccing battery banks over 200Ah the answer is rapidly turning into a "no, I cannot get away with it".

There is a small angle on the equipment side, in that 12V/24V stuff is more readily available and often cheaper. I'm from the blue team, as most of you well know, and just take a look through the line-up to see my point, a lot of the more affordable MPPTs are limited to a 24V system. The question still remains, if I cannot get away with it (due to operational constraints on the current side), then you should not do 24V.

I'm happy with my 24V system for now. The direction in which I am taking it is going to be backup of essential loads, and grid-parallel battery up to 1.5KVA max to eliminate base loads. So I can get away with it.

48V is always better than 24V. Always. Just like a Toyota is always better than an Isuzu... but sometimes you can get away with the Isuzu.

(Yes... that was deliberate :-P )

[DeepBass9]

Quote

The 5000 is the total watt hours per day and the 1500 the peak.

That is pretty much the loads that I have. Peaks are the microwave or inverter welder, general average load is 300-400W in the day and 200W at night. I have a 48V system, 8x 150Ah batteries and 6 x 300W panels, with a generator backup. I know from experience that if my system was just a bit smaller, I would have problems and have to run the generator every day. Currently the generator is only used for an hour or so in winter or when overcast. Now that the days are lengthening, it is not neccesary to run the generator unless there are exceptional loads.

I wouldn't recommend going 24V as you limit the size of the system. Rather go 48v and be done with it.

Staff and cottage are on 12V solar for lighting, solar geyser and donkey for hot water, and wood and gas for cooking.

[Weasel]

Welcome to the forum @Farmer

What type of generator do you have. Perhaps look at some autostart options. 

Important thing is to get your baseline correct for how far you want to expand. In otherwords get your batteries and inverter right. 

Ive found too much batteries is not a mistake. You can always add more panels and other goodies but batteries not really. 

[Guest]

19 minutes ago, plonkster said:

... but sometimes you can get away with the Isuzu.

There, you have ruined the friendship getting personal! 

43 minutes ago, plonkster said:

I'm jealous of the low currents you 48 Volters have to deal with

Grow a pare man. Seriously, it is not such an issue once the system is up and running. If you drove a Isuzu and was called TTT, then I will be worried.

19 minutes ago, plonkster said:

... 48V is always better than 24V ...

Nope, its like saying Toyota fits all sizes. For if what you and DeepBass said was true, then this would have been on a 48v system. 

2 minutes ago, DeepBass9 said:

Staff and cottage are on 12V solar for lighting ...

 

1 minute ago, Weasel said:

In otherwords get your batteries and inverter right

+1 YES, make sure of the load.

Off grid on a farm is a no-brainer, house loads and 48v bank versus gennie as backup ... batteries make more sense.

BUT, if the load is a few LED lights ... all depends on needs versus wants and farmers are wiser than city boys with loads. 

IF the system expands in the future, the smaller system teaches ones a lot and can move to the workers houses, or stay in place for what it was intended for initially until it breaks, or it is used for light at the gate, in the barn / stoor or whatever. Always a place for a smaller system.

 

It all depends on the loads and for how long they need power. That dictates the batteries. Once you have that down, then you can decided what bank is best. 

BUT ... when you calculate the load you obviously decide the max load and peaks you need to cater for to determine the inverter size. THAT 10 to 1 forces you to 48v by default. But hey, if you want to run a few LED's on 48v 5000va Axpert 360ah bank with Eskom in place, go ahead. 

 

And then there is the little matter of the DA and EFF weakening the other party which may result in Eskom getting sorted in the next number of years, which means the scaremongering of increased Eskom costs and power failures becomes less of an argument making the sums for batteries complicated if you have access to Eskom power in cities / dorpies, with grid tie allowed and all that.

Has ANYONE done the sums of what it really costs to power a microwave using Eskom versus batteries? Or a kettle or a snappy chef? These loads forces a increase in inverter size necessitating a 48v bank. So everything becomes more expensive and for what saving ... not today, this month, nee, the saving year after year with batt replacements and their increased costs due to inflation and R/$ fiasco's. Take everything into account. Till then, I am patiently waiting for the first batch of battery replacements to happen for the city folk. 

 

Have said my side. Farmer to decide the loads for the bigger they are, the better the case for a 48v system. The smaller they are, I disagree running a few lights on 48v system.

[___]

42 minutes ago, The Terrible Triplett said:

Nope, its like saying Toyota fits all sizes.

Man, I'm just saying I don't know a single person who bought the KB because he thought it was the better bakkie. They buy it because it is more affordable. Nothing wrong with that... bang for buck and all... but if you have the money you buy the Hilux. At least where I come from. In the same manner, I don't know anybody who goes 24V because it is better. We do it because it is cheaper and we can get away with it :-)

[Guest]

4 minutes ago, plonkster said:

... but if you have the money you buy the Hilux. 

I know what you meant. 

Nope, disagree again. You have the cash, the Isuzu does just fine, is paid off, does not break and services are as cheap as you can get. Only irritation is you drive a bit slower between point A and B - but then there are speed limits for a reason, so why buy better just because you can afford too, makes no sense when you look around at the State of the Economy or weigh up the benefit of a new vehicle, being a need or a want?

7 minutes ago, plonkster said:

We do it because it is cheaper and we can get away with it :-)

Precisely. Take the extra cash you save on batteries and larger everything else and stash it away for the coming rainy day, not if, when it comes, for that day you need to replace parts or batteries, you wish you had the savings and / or you could get away with 50% less. 

NOTHING tics me off more as the day I realize I could have done the exact same thing @ 50% less.
NOTHING so worrysome as when I get caught in getting bigger and better and then Wife asks: Why do we need it?

Being in cities with Eskom, batteries are a luxury in my opinion, if there are no power failures or coming power failures. Lots of panels for daily loads, minimum batteries for just in case there are a failure or two.

[Chris Hobson]

In a off-grid system ideally you power 99% of your load 80% of the time. Savings are achieved by not running the generator. If you need to run the generator to power heavy loads 2-3 times a week then I would look at increasing number of panels  and size of inverter to cope with the load. Design you system with room to expand. You  will find things that you did by hand you now do using power tools since the power is now available. There is no Eskom to power incidental loads.  Solar is nearly always cheaper than gennie so get as much practical powered by solar. If you have occasional high demand load leave that to be powered by the gennie. For the rest aim at powering it with solar even if you do it in stages.

[DeepBass9]

That is one of the nice things about solar, is that it is modular, but only once you have set up the guts of the system to allow for expansion.

[Guest]

21 minutes ago, DeepBass9 said:

That is one of the nice things about solar, is that it is modular, but only once you have set up the guts of the system to allow for expansion.

That is very true.

And if you do get yourself in a corner, do not stop and run, change, sell, smous, trade, horse trade, split systems ... there are many ways to skin a cat.

[___]

Resale value on second hand solar stuff is generally quite poor and the 12v stuff does better because you can sell to the 4x4 market, but it is somewhat of a consolation that moneys can be recovered.

Sent from my GT-I9195 using Tapatalk

[Farmer]

On 08 August 2016 at 2:23 PM, DeepBass9 said:

That is pretty much the loads that I have. Peaks are the microwave or inverter welder, general average load is 300-400W in the day and 200W at night. I have a 48V system, 8x 150Ah batteries and 6 x 300W panels, with a generator backup. I know from experience that if my system was just a bit smaller, I would have problems and have to run the generator every day. Currently the generator is only used for an hour or so in winter or when overcast. Now that the days are lengthening, it is not neccesary to run the generator unless there are exceptional loads.

I wouldn't recommend going 24V as you limit the size of the system. Rather go 48v and be done with it.

Staff and cottage are on 12V solar for lighting, solar geyser and donkey for hot water, and wood and gas for cooking.

Deepbass..I think this is how my system should look like yours.I would like to go for more panels to directdrive my freezer,washing  machine computer and charging during daytime and use the gennie for pumping water and power for the workers for 3 hours at night.I only need the batt for the lights and freezer during nighttime.