Victron Inverters

[Beanyboy57]

I have 2 CCs


In my opinion, in solar systems, in life in general and in the words of Mr Micawber (a Charles Dickens character)
You are OK if your income is more that your outgoing.

I remember Mr Micawber very well (I think it was Bob Hoskins played that character in the BBC play), he had some good advice for all of us about spending more than we earn, but those guys that sell credit cards would try to discredit him hahaha.
I live in Perth WA, I think we are in one of the sunniest places on the planet, I think over the last 30 years I can count on one hand when it rained for more than one day, we have a huge desalination plant here to supply us with enough fresh water. I have a friend in France who said that she would be out in the sun everyday if she was here, but you know, when you are here, you want to hide from the sun as much as possible!!! We have the highest rate of skin cancer in the world here. It's probably similar to where you are as far as the amount of sunlight goes.

Although there is an insolation chart for Perth, I can hardly believe that is is accurate given how much sunlight we get each day and how little cloud cover we get. That's why I think that we must use our own (well researched) judgement coupled with the advice of the experts when we are planning an off-grid solar powered system. I think any 'expert' will give you the worst case scenario so that when you plan you have the best plan possible, just like a doctor will give you the worst case assessment so that you listen to the advice he or she offers.

[cortijo]

I have been following this thread with interest as I am now a firm believer that any power system must be designed using the laws of physics and a lot of help from the experts but as we all know what happens in reality when humans are involved is that changes are made and theory is severely tested, also temperature plays a large part in the life of batteries as well as maintenance.
It seems like you are getting good value out of your current setup so far apart from the incident with the Victron inverter. I also have the same inverter but I made sure that my battery bank never goes more than 25% DOD (75% full) so I have never had to test out the low voltage cut off. My system is just for lighting and power tools.
I would be interested to know what brand of batteries you are using and how you have them connected together. Also where you have placed your connections from the CC and Inverter (could you upload a pic?). Also when you measure your batteries are you relying totally on your energy meter to measure the voltage or do you use a quality hydrometer to measure each cell after they have had time to settle?
Cheers
Jon

I have 2 CCs
They both measure the voltage.
The inverter also measures the voltage.
The CC's have more or less the same reading but the Victron inverter reading is higher.

I must get a hydrometer and learn how to use it.

I am planning to have a section on my solar set up on my blog with photos.
The batteries ccs and inverter are all close together in one room.

One of the problems with system design is that a big decision is the choice of batteries.
If properly treated the batteries may last 5 years.
But in 5 years their use may change.

This is my case:
When I bought my batteries my mountain house was only used for weekends.
I like it so much up here that I now spend a lot of time here. From March - November this year I have been here permanently, 100% off grid.

The choice of batteries was made by an installer.
At this time I did not understand anything about batteries or solar systems so I had to go along with what my "expert" thought best.
It probably was the right amount of battery for my usage at the time.

The big difference between my conception of a good system and other people on this thread and also books I have read is that other people believe that
the batteries should be able to withstand 5 days of no sun whereas I would be happy with 1 day.

Maybe the reason I believe this is because I live in Andalucia Spain which has a very high amount of sunlight hours and 3 days without sun happens very infrequently. Also if there is no sun it is possible to quickly minimise electricity use to a minimum.
Just 1 or 2 laptops and a 6 watt router so maybe 90 watts.
The generator I have is the smallest you can buy.
It has a 450 or 900 watt setting.
On the 450 watt setting it will go for a lot of hours for maybe 3 euros.
Even on a cloudy day the panels take in 150 watts.

These are the reasons why my batteries are still OK.

In my opinion, in solar systems, in life in general and in the words of Mr Micawber (a Charles Dickens character)
You are OK if your income is more that your outgoing.

Mr Micawber
"Annual income twenty pounds, annual expenditure nineteen pounds nineteen and six, result happiness. Annual income twenty pounds, annual expenditure twenty pounds ought and six, result misery."

In the case of a solar system you have to take some inefficiency into the equation.

With a solar system:
If your big expenditure happens at times of maximum income and at times when there is no income the expenditure is low and you have enough flexibility to vary the expenditure then you are more likely to be happy with the system.

Here is some more info on my system.

The CC s are PWM

I have a 24 volt system
I have 12 of the following batteries

Classic 5 OPzS 380 2v Solar Liquid Cell
Voltage: 2V
Capacity: 380Ah @ c120

I mainly chose to have a 1200 watt system because SUNKING (from this forum) said I would need 1200 watts charging power for my batteries.

(I hope that SUNKING knows what he is talking about because I have trusted his figures.)

See post

http://www.solarpaneltalk.com/showth...4185#post44185

I now have 2 charge controllers.
One with 250 watts of panels the other has 950 watts.

[Beanyboy57]

down to 18.6 Volts once when I bought the victron inverter because of their ridiculous (in my opinion) default setting.
Sunking said that my batteries would be toast that low but they seem OK.
That was the only reason the freezer warmed up.
I went away for 5 days and the inverter cut me off and did not come on again.

I have been told by everyone that it is not a good idea to mix new batteries with old ones so I will wait for my current batteries to die before getting new ones.
If I am perfectly happy with my system why would I buy new batteries?

I have been following this thread with interest as I am now a firm believer that any power system must be designed using the laws of physics and a lot of help from the experts but as we all know what happens in reality when humans are involved is that changes are made and theory is severely tested, also temperature plays a large part in the life of batteries as well as maintenance.
It seems like you are getting good value out of your current setup so far apart from the incident with the Victron inverter. I also have the same inverter but I made sure that my battery bank never goes more than 25% DOD (75% full) so I have never had to test out the low voltage cut off. My system is just for lighting and power tools.
I would be interested to know what brand of batteries you are using and how you have them connected together. Also where you have placed your connections from the CC and Inverter (could you upload a pic?). Also when you measure your batteries are you relying totally on your energy meter to measure the voltage or do you use a quality hydrometer to measure each cell after they have had time to settle?
Cheers
Jon

[Sunking]

Here is a table from a well respected Battery Manufacture .
Trojan Battery

[cortijo]

Which means you are discharging your batteries 75% DOD leaving you with only 25% capacity remaining. .

Thank you for all the replies to my questions:

Sunking: In an earlier post on this thread you said that 23.8 Volts would be @ 60% DOD

I just said that the batteries went down to 24.1 and now you say that 24.1 is 75% DOD

To me that does not make sense.

23.8 Volts is the emergency cut off point (it almost never gets this low)
24.1 seems to me a fairly safe low point.

The figure of 75% DOD would mean that I would get about 600 cycles.
According to the info you supplied.

20% DOD @ 3000 Cycles
30% DOD @ 2500 Cycles
50% DOD @ 1000 Cycles
80% DOD @ 400 Cycles

My batteries are over 3 years old and have done about 1200 cycles.
So they should have gone dead about 18 months ago???

Can DOD be expressed as a voltage?
Is there a formula to change DOD to a voltage?

So that you could say for example 20% DOD of a 24 volt battery is X volts.



Lots of other things don't make sense.

Victron energy seem happy to sell an inverter which out of the box would could trash a battery bank on the first night.
There is nothing in the documentation which says that the default cut off point is so low.
One post pointed out that this is because they want to keep the energy flowing in case it is mission critical.
I would say that not trashing a battery bank which could cost $10 000 is mission critical.
After spending 900 euros I think it would be more reasonable to include a usb port in the actual product rather than having to
spend an extra 65 euros on buying a dongle which will convert an ethernet plug into a usb cable. (what a crazy idea)
In this day an age when a wifi enabled kindle costs 79 euros a 900 euro inverter ought to have wifi.


QUOTE:

There are two schools of thought.

1. Is to disable any Low Voltage Disconnect. This is usually done for Mission Critical applications where the cost of destroying batteries from completely discharging them is not a concern.

2. Use the LVD feature and set it to 50% Depth of Discharge to preserve and save the batteries. When used the LVD and LVR voltages must be chosen. Here are my recomendations.

LVD = 23.8 Volts @ 60% DOD
LVR = 26 volts

[Sunking]

By the next morning they are around 24.1

Which means you are discharging your batteries 75% DOD leaving you with only 25% capacity remaining. .

[Sunny Solar]

Cortijo ,,Yes it is not good to mix new batteries with a bank of old ones.

Really the bottom line here is if you are happy with the system as it is, Dont change it.. If it appears to be functioning well enough to satisfy you then thats it.

I did previously say why I think Victron set the cut off so low.No matter where its set it wont please everyone.

[cortijo]

Ever hear of the term "false" economy? What these guys are telling you, in blunt terms, is that if you don't add more batteries, the draw you're putting on your existing batteries will kill them, dead, in a staggeringly short period of time.

So would you rather replace your current insufficient batteries at, say, a few hundred Euros per year, or would you rather spend a thousand Euros now, and amortize that over five years, to then have a biogger bank of batteries, still working functionally, five years from now, and not have to worry about damp burgers because the freezer died again? Same cost output, far different end results.

At about 1 hour before sundown my batteries normally show about 27C
Half an hour after sundown they normally show around 24.6 which as far as I know means fully charged.

By the next morning they are around 24.1

Then the sun gets going again.

So my batteries don't get very low.

On a day of no sun the inverter will cut out at 23.8 so the batteries don't get too low.

The inverter cuts out like this about once a month maybe.

I don't think I am thrashing my batteries.

They are 3 years old.

If I get another 2 years out of them I will be happy.

I did go down to 18.6 Volts once when I bought the victron inverter because of their ridiculous (in my opinion) default setting.
Sunking said that my batteries would be toast that low but they seem OK.
That was the only reason the freezer warmed up.
I went away for 5 days and the inverter cut me off and did not come on again.

I have been told by everyone that it is not a good idea to mix new batteries with old ones so I will wait for my current batteries to die before getting new ones.
If I am perfectly happy with my system why would I buy new batteries?

[russ]

Also - Unless you have one of the rare locations with constant and adequate wind to make a turbine useful it would be a waste of time.

The cheap turbines sold all around are really nothing more than boat anchors waiting to be used - good ones are expensive and have to be on a tall tower.

[Vern Faulkner]

Ever hear of the term "false" economy? What these guys are telling you, in blunt terms, is that if you don't add more batteries, the draw you're putting on your existing batteries will kill them, dead, in a staggeringly short period of time.

So would you rather replace your current insufficient batteries at, say, a few hundred Euros per year, or would you rather spend a thousand Euros now, and amortize that over five years, to then have a biogger bank of batteries, still working functionally, five years from now, and not have to worry about damp burgers because the freezer died again? Same cost output, far different end results.

[cortijo]

I have great respect for all the experts here.
I chose the amount of new solar panels based on what I was advised here.

My experiences based on reality don't tie up with the figures.

In the summer I kept a 70m3 swimming pool clean.
Had an average of 8 people staying here.
Kept all their clothes clean (using a cold water automatic washing machine)
Had 3 or 4 laptops connected to internet.

I never used a generator one and that is not a lie.
The system I had before was very underpowered.

Last December I only had 250 watts of solar panel power.
Most evenings I put the generator on for a hour or so.
This must have cost me about 12 euros over the month.

This December with my new panels I expect to be very comfortable and only use a bit of generator power in case of bad weather.

You have to take into account that in the winter there is no swimming pool pump
The freezer can be outside at 4C ambiente temp rather than 30C ambient temp.
The lower temperature of the panels give a better performance.

There seems to be a lot of difference between what theoretically should happen and what is actually happening.

Maybe it is because I got used to the previous underpowered system.
All my lights are LED tubes or LEDs.
The high load items are only put on between 12 noon and 4pm.
The rest of the time I only use about 120 watts.
I only consider that the batteries have to get me through the night.

My batteries are now 3 years old and seem to be in good condition.
When I have to replace them I will get bigger ones if I have enogh money
but I am happy with my current system.

Why is there so much difference between theory and practice?
Maybe it is due to attitude and adaptation.

If it looks a bit cloudy I will not run the pool pump.
If there is lots of sun and I go away for the weekend I would put the freezer down to minus 35C.

When you do your calculations you have to take into account how attentive the house user is in optimising the available sun with the amount used. Maybe that can explain the difference.

It seems to me that it is much more efficient to use the sun directly rather than storing the energy and using it later.

Also there is the major difference in opinion.

I don't agree that it is worth the expense of getting a massive battery bank that will give power during 4 or 5 days of no sun.

I would rather spend money on an automatic start generator or even a wind turbine.

[Sunny Solar]

In the USA and live in a large city or near one and shop around you can get an authentic Trojan T105 for around $115 to $130 USD. I think that converts to $110 to $125 AUD.

The Trojan T105 is available here in AUS at Brisbane $226. This is my point before you can be certain about cost efectiveness you need to know the cost of the item in the country its going to be bought in.
A good quality 30a MPPT controller here will set you back close to $300 but a very good 30a PWM one will cost $130.

[Sunking]

Sorry, this is not quite on the topic of the thread but I am interested in what other's pay.
A Century/Yuasa T105 6V 225 ahr battery (almost exact copy of the Trojan) $190 Australian. How does that compare to other countries?

In the USA and live in a large city or near one and shop around you can get an authentic Trojan T105 for around $115 to $130 USD. I think that converts to $110 to $125 AUD.

[Beanyboy57]

All the above would need to be first calculated out for cost and then see what is cost effective .Replacing the new expanded batteries each 4 years may be a more expensive exercise. It can all only be calculated out if all the costs of fuel and items are worked out in that country.,

Example :battery prices for a given brand name..in many countries are at least 50% higher than USA.

Sorry, this is not quite on the topic of the thread but I am interested in what other's pay.
A Century/Yuasa T105 6V 225 ahr battery (almost exact copy of the Trojan) $190 Australian. How does that compare to other countries?
30amp MPPT programmable CC with temperature control around $230 (Chinese brand)

[Sunny Solar]

That is not cost effective. Gen fuel is expensive.

That would depend on many variables.
His present system is inadequate to really provide a below 50% battery discharge each day under ideal conditions.

He claims he never used a generator at all in July August September,.But I think he should have run it sometimes.

The cost of expanding the batteries and panels x5 is going to be very high and so is the battery replacement every 4 years or so.
If he doubled his present batteries and panels he may only need to infrequently need to run the generator and only for short periods,to make up the solar shortfall.

All the above would need to be first calculated out for cost and then see what is cost effective .Replacing the new expanded batteries each 4 years may be a more expensive exercise. It can all only be calculated out if all the costs of fuel and items are worked out in that country.,

Example :battery prices for a given brand name..in many countries are at least 50% higher than USA.