How to totally secure an off-grid PV system with fuses ?

[Hava'i]

Thank you Sunking for answering me.

First I want you to be sure I deeply respect your knowledge in all these matters related to solar power and I'm very grateful that you take time to share it with us.

I wouldn't dare to insist if I had the slightest doubt about what I said in my past posts :

None of the people I know with BP systems have a generator but their batteries last at least 8 years.
I'm not even sure there's a 6 KW generator on the island...
I've spent weeks at my friend's place and even after 5 days we had lights. Of course we were very careful, not opening the fridge too often etc... just common good sense.

I hope you don't think I'm crazy or worse, lying when I say so, why would I do that ?

I see your point and it makes sense to me but I have to say what I saw with my eyes and it's very frustrating cause I don't know how to explain it.

That being said I'm sure you're right and that with a generator boost the batteries would have last even longer.

We're at about the same latitude than Hawaii, so maybe we get just a little bit more sun.
One of the reason might be that he's very conservative. If there's no sun there's no TV etc...
But I'd gladly do the same just to have lights instead of oil lamps.

Once again, I don't know how to explain that. I have trouble believing BP/Apex guys could know something others don't.
They were very arrogant people, which is the reason we never sign with them. They never once did the maintenance as scheduled. My friend went crazy about that. Once they didn't came for 3 years but although the water was almost to the plates when they opened the batteries box to fill them (they're in a big plastic box with padlock on. No more padlock, no more guarantee...) the system was running perfectly...

So you see, I'm not exactly advertising for them...

I could add more panels but they wouldn't get as much sun as the 6. These will have the sun direct from 6.30 am to 3.30 pm

If you think of some other way, please tell me. What about a small wind turbine like Paul suggested ? Would it really compensate for the generator ?

Thank you in advance.

[SunEagle]

I have to admit that Hoppecke OPzS battery seems to be pretty rugged. They claim 1500 cycles at 80% DOD up to 4000 cycles at 30% DOD dependent on the ambient temp. Of course those numbers may only be if you accept their long term Maintenance plan.

[Hava'i]

Hi SunEagle,

I can attest that even with terrible maintenance they may last up to 12 years.
The BP/Apex contract stipulated one to two visit a year but it never happened.
Now the batteries I'm talking about were made 12 years ago. Things may have changed but I'd trust Germans on building to last.

But as Sunking was saying, it would be even better with a generator. When you have one.

I'll try to look for more panels.

Wind's direction changes too much in my valley for a wind turbine.

[SunEagle]

Hi SunEagle,

I can attest that even with terrible maintenance they may last up to 12 years.
The BP/Apex contract stipulated one to two visit a year but it never happened.
Now the batteries I'm talking about were made 12 years ago. Things may have changed but I'd trust Germans on building to last.

But as Sunking was saying, it would be even better with a generator. When you have one.

I'll try to look for more panels.

Wind's direction changes too much in my valley for a wind turbine.

The 12 years of life of those batteries may be a combination of low ambient temperature and only 10% DOD daily. It seems that the less you use those batteries the longer they live.

They are even "designed" to last 20 years as long as they are at 20C and are not used but kept on a float charge.

The problem with most Off Grid people is that until they learn to manage their consumption they end up deeply discharging their small battery system which don't last. A bigger battery system using the OPzS batteries may last longer but may also cost a lot more up front.

I agree with Sunking. Having a generator to recharge the battery system is a good insurance policy. If you go without good sunlight for a few days that expensive battery system will not live as long. Of course where you live you might not get extended days without sunshine so a generator may not be required.

[Hava'i]

Thank you SunEagle, I totally agree with all of you guys, it's just that there's no way I can get one now. Even if I could, there isn't one for sale on the island.
As for temperature we never ever go under 20 °C at night. During the day it's mostly 28 but if there's no wind it goes easily to 32 °C in the shade.
My friends batteries are in his garage in a big plastic box with little ventilation.
We sometimes have many days in a row without sun but my friend is smart enough not to abuse the batteries at these times. Except for being smart, I plan to do just the same...

Thanks again to all of you for your help.
I'll be back for the fuse questions

[SunEagle]

Thank you SunEagle, I totally agree with all of you guys, it's just that there's no way I can get one now. Even if I could, there isn't one for sale on the island.
As for temperature we never ever go under 20 °C at night. During the day it's mostly 28 but if there's no wind it goes easily to 32 °C in the shade.
My friends batteries are in his garage in a big plastic box with little ventilation.
We sometimes have many days in a row without sun but my friend is smart enough not to abuse the batteries at these times. Except for being smart, I plan to do just the same...

Thanks again to all of you for your help.
I'll be back for the fuse questions

Well it sounds like you are at least thinking smart but understanding the limitation of a battery system without the sun to charge it.

It seems those batteries prefer cooler temps around 20C and have a shorter life the higher it goes. I thought I had read the Design life was only 10 years at 30C and 5 years at 40C. So keeping them cool will help extend their life. (At least according to the Victron Energy data sheet for the OPzS series)

[Hava'i]

The way to keep them cool at my place would be building a concrete room, fill the bricks and put tiles on the floor and walls.
That's what I did to some extent (I skipped the tiles on the walls..) for my house and it's always 3°C cooler inside than outside.