Inverter and batteries

adielk

Expert Member
Joined
May 21, 2009
Messages
4,056
I have got 4 x 102ah batteries to start with. Any ones added will be within a week or 2 of commissioning the system. Once I have data regarding usage, peak, average etc. My whole plan is based on a 50% "draw" (i.e. 1500w) as my constant and a 50% DoD over a 3 hour period (initially 120 till I can get some data)


I have based my setup on total off grid systems that have been running for 2 years or more. So I have used actual data. I have explained that it is not being used as a grid tied system. I am going to use the inverter as it is designed to be used. It is designed to be a hybrid inverter meaning that it accepts multiple inputs of power, can prioritise charging of batteries for any of the sources and deliver regulated power. People have varying ideas on what grid-tied means. That is where confusing comes in.

In order of importance:
To get a constant voltage as rural power fluctuates badly.
UPS for times when we have short power outages between 20 seconds and 5 minutes which happen, at least twice a day as Eskom balances city power by rerouting rural power.
UPS for extended outages of 1 hour or more, due to loadshedding, storms, cable theft (whole district goes out until they can isolate the affected branch). Part of the time a generator will be used until critical farm applications have completed their cycle (between 1 hour and 3 hours, but no more within a 12 hour period).
In the future the addition of pv for daytime charging of batteries (when draw is minimal and around 500w) to reduce usage of Eskom.

The system is not designed to be utility independent. it will not be used for intensive power consumption (laundry, microwave, oven, geyser) of over 1000w peak per device and 300w average per device. I have spent the last two weeks logging appliance usage using a watt meter to get peak and average consumption.

I have spent a lot of time reading where people find problems and how they have solved them. I have spent time with people that have been running off grid for 2 years+, so they have had time to troubleshoot, adapt and let everything settle. I could also have spent R70k and had a 10kw total off grid system, but i have worked around what I need and what I can afford. So I will have tv, internet, lights, fans and fridge in my whole house for 2 hours minimum.
What system costs R70k?

Thanks
 

MightyQuin

Honorary Master
Joined
Oct 6, 2010
Messages
11,676

RedViking

Honorary Master
Joined
Feb 23, 2012
Messages
16,092
View attachment 619792
Considering screwing a DIN rail left of the fuses to hold 2 x 2 pole isolators. One for utility in and one for inverter out.
My friend didn't arrive to solder terminal rings yet.
4 x 102ah 12v batteries. Will be joined in pairs to create 2 x 102ah 24v batteries = 204ah 24v.
View attachment 619794
4 core 4mm armored cable I had laying around. One pair from utility and one pair back to isolator on DB. I have earth cable that I use.
View attachment 619796
2 x 100A dc fuses that will also serve as bus bars for cables from batteries.
View attachment 619798
Looks great!!
 

RedViking

Honorary Master
Joined
Feb 23, 2012
Messages
16,092
Unfortunately they already ran out of batteries. Now there will be up to a 20 working days wait, after you have already purchased it.

That is why I bought all my batteries and inverters during the days when everybody has forgotten about load shedding.
So mine should arrive when loadshedding is over. :laugh:
 

deweyzeph

Executive Member
Joined
Apr 17, 2009
Messages
6,634
It is still good enough for what it was designed to do, is it not?
https://www.altestore.com/blog/2015...-sine-wave-whats-the-difference/#.XGZdm1wzaUk

A modified sine wave inverter can be used for simple systems that don’t have any delicate electronics or audio equipment that may pick up the choppy wave and produce a hum. Old tube TVs and motors with brushes are usually ok with modified sine wave. Your digital clock will likely act funky, and battery rechargers quite often just plain won’t work. Some equipment may seem to be working fine, but may run hotter than with a pure sine wave and reduce the life of it.

Take heed if you’re considering buying a modified square wave inverter to shave a few bucks off your system costs. A whole raft of modern appliances won’t run as well and some not at all on this waveform.
 

RedViking

Honorary Master
Joined
Feb 23, 2012
Messages
16,092
The problem is that these cheap and nasty power trolleys use modified sine wave inverters.
This has been debated over and over and over again. There is nothing wrong with modified sign wive if you use it on the right equipment. It is also clearly stated that these units are used for backup only, so you are not going to run your whole house on it. The system Dairyfarmer is running is a good solution for that. One size does not fit all.
 

Chuckmyster

Executive Member
Joined
Aug 2, 2016
Messages
5,330
This has been debated over and over and over again. There is nothing wrong with modified sign wive if you use it on the right equipment. It is also clearly stated that these units are used for backup only, so you are not going to run your whole house on it. The system Dairyfarmer is running is a good solution for that. One size does not fit all.
every week it is deja vu here on MyBB. Wish there was a Loadshedding section on the forum where all these threads can go sit for future people arriving and asking the same questions again. Can't blame them really as articles are scattered everywhere.

Please @rpm start a Forums --> General Discussions --> Loadshedding section as this topic is here to stay for many years to come :thumbsup: Then move all these threads there so it is easier for people to find relevant articles. Thank You
 

deweyzeph

Executive Member
Joined
Apr 17, 2009
Messages
6,634
This has been debated over and over and over again. There is nothing wrong with modified sign wive if you use it on the right equipment. It is also clearly stated that these units are used for backup only, so you are not going to run your whole house on it. The system Dairyfarmer is running is a good solution for that. One size does not fit all.
That's great if by "right equipment" you mean nothing electronic. But what household doesn't have electronic equipment like LCD TV's, laptops, cellphone chargers, etc that almost every expert will tell you should NOT be run on modified sine wave inverters.
 

RedViking

Honorary Master
Joined
Feb 23, 2012
Messages
16,092
That's great if by "right equipment" you mean nothing electronic. But what household doesn't have electronic equipment like LCD TV's, laptops, cellphone chargers, etc that almost every expert will tell you should NOT be run on modified sine wave inverters.
Stop talking nonsense.
 

Geoff.D

Executive Member
Joined
Aug 4, 2005
Messages
8,921
The issue is "electronics" is everywhere these days. Every new device except possibly stoves and ovens is now full of the "stuff". And what is also not accounted for when the catch-all statement is made about "Modified Sine Wave" is not suitable for "electronics", is that Modified Sine Wave inverters have also evolved. The modern designs are far far better than the older designs.
Now whether we can claim that the el-cheapo inverters we get these days are in that category ---- that is the question!
There is only one way to know, and that is to have a look at the specification (if of course, the supplier provides you with a spec).
 

RedViking

Honorary Master
Joined
Feb 23, 2012
Messages
16,092
The issue is "electronics" is everywhere these days. Every new device except possibly stoves and ovens is now full of the "stuff". And what is also not accounted for when the catch-all statement is made about "Modified Sine Wave" is not suitable for "electronics", is that Modified Sine Wave inverters have also evolved. The modern designs are far far better than the older designs.
Now whether we can claim that the el-cheapo inverters we get these days are in that category ---- that is the question!
There is only one way to know, and that is to have a look at the specification (if of course, the supplier provides you with a spec).
I've done my research are read reviews, and modified sine wave is fine. Most modern equipment is also designed to allow for modified sign wave. But this has already been debated enough in other threads.
 
Top