Hi from SA South Coast

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Hi from SA South Coast

Postby amongstmyselves » Wed Jan 04, 2017 12:19 pm

Hi all,

My name is Steve and we've recently purchased a house in Hindmarsh Valley which is off the grid and has a 10 year old and failing power system. We've already ordered a new system which will be very self sufficient as the current old system is not. Ideally I would have come here first but the old system needed dealing with immediately plus the old system only partly functions and band aids would not help. I'm hopeful that the old system will find a new home with someone here looking for something to fix up. Anyhow, looking forward to seeing other people's projects.

Steve
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Re: Hi from SA South Coast

Postby Gordon-Loomberah » Wed Jan 04, 2017 12:55 pm

Welcome to the Energy Matters Forums Steve :)

What is the problem with the old system? If it has the original battery, then I'd expect it would probably be on its last legs by now.
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Re: Hi from SA South Coast

Postby amongstmyselves » Wed Jan 04, 2017 1:39 pm

Cheers Gordon,

Yeah the batteries aren't in good shape at all. The last owner only used the house as a holiday house and spent little time here over the last 4 years and never got the system checked. There are so many small issues with the system ie: half the panels weren't working due to blown fuses. Their solution was to run the generator all the time during night time hours when they were awake. They rewired the generator control so that it would run from a timer and the autostart connection from the Outback controller was disconnected.
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Re: Hi from SA South Coast

Postby Gordon-Loomberah » Wed Jan 04, 2017 2:37 pm

If the inverter and charge controller are still working satisfactorily (and are large enough), you may only need to get yourself a new battery, and Lithium is the best choice these days. Programmable charge controllers such as the Flexmax from Outback Power will work perfectly well with a LiFePO4 battery.

If some of the fuses for the panels are blown, they may be undersized, or it's been wired incorrectly, as it is not something that would normally occur.
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Re: Hi from SA South Coast

Postby amongstmyselves » Wed Jan 04, 2017 3:22 pm

The old system has two inverters and charge controllers. One of the inverters has died. My concern with this system was that a major investment in batteries for this system could be taking a risk should the other components give up. I don't mind the idea of tinkering with this sort of system but to be honest having a reliable almost maintenance free system is really what we want and I also think what most people would want. One of the major concerns is that the current solar setup is located 300M from the house and having the rely on that cable or the thought of having to replace that cable made us decide to put the new system within the house. The only thing we'll use from the old system is the Honda Generator which the system designer said would be ideal but also may not get used at all. We'll see ?

The new system will still use lead acid batteries because the system designer says that LiFePO4 are not suited to our system due to their low autonomy (the ‘fat’ needed at times of low energy input or increased demand). Their cost is still quite high as well. That is their words not mine. I'm happy with this as the life of the battery technologies are similar. Though I am interested in other peoples thoughts and evidence.

The new system is quite beefy - 36kWh of battery storage and 6.4kWp of panels. We were interested in putting a small wind turbine in as well to avoid the generator but they wouldn't guarantee a wind turbine due to mechanical reliability and also intermittent power generation. Nice idea but in reality another tinkering type choice.

It's all happened quite quickly and I think we've made the right choice.
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Re: Hi from SA South Coast

Postby Gordon-Loomberah » Wed Jan 04, 2017 3:45 pm

300m from the house is certainly a big issue, moving it closer makes a lot of sense.

Since you have made your choice re batteries, I'll just make a few comments- you can discharge LiFePO4 a lot deeper than Lead-acid, so ~20kWh of LiFePO4 could do the same work (only better) than your 36kWh of Pb-acid. Lithium is a lot more efficient than Pb-acid, so you effectively have more energy available form your panels, see this thread:

solar-wind-gear/topic5108.html

On a cents per kWh basis, I'm pretty sure LiFePO4 (CALB, Winston etc) comes out significantly less expensive than decent quality Pb-acid now.

I don't know what your daily energy usage is like, but as a comparison I managed for 2 years with no generator usage and around 12kWh/day average energy use over winter, and lots more in summer, with 21kWh of LiFePO4 and around 4kW of PV. However, I'd expect that you may see more winter cloud than I do.

In almost all cases, for an equal financial investment in PV panels or wind turbine, the panels will deliver a lot more energy. If you lived in a particularly cloudy, unpleasantly windy area, then wind may be worthwhile.
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Re: Hi from SA South Coast

Postby amongstmyselves » Wed Jan 04, 2017 4:01 pm

Hmm I see the argument for LiFePO4 is quite good. Well not really an argument, more of stating fact. Like I mentioned before, if I had more time I would have researched it a little more.

We did a load profile for the company as part of the quote and we presumed on a few items, new house and all that, we came out to about 14Kwh/day in summer and 12.46 in winter. Mind you this takes into account possible future installation of multiple air conditioning units. At the moment we don't have any cooling, not even ceiling fans, electricians are currently here installing 7 of them. I have been monitoring the meter in the solar shed and we've been using only 8kWh a day. We're being conservative in usage though as not to upset the generator gods. We've not used the dishwasher or the electric oven. Who puts an electric oven in an off the grid house ? The lights are also mostly still halogen downlights, again the electrician is replacing these at this very moment.

This area is a more cloudy. Regularly 4 to 10 degrees cooler than Adelaide. Antarctica is just to the south :D

There is quite a lot of wind up here according to the neighbors who are looking into wind generation as an adjunct to their not so nicely placed solar panels. There are 4 properties up here which are all off the grid.

Given your figures, the system specified for us certainly seems to be about right then.
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Re: Hi from SA South Coast

Postby davidg » Wed Jan 04, 2017 11:22 pm

Gordon-Loomberah wrote:300m from the house is certainly a big issue

Oh I don't know ................. depends on the size of the cable ............... I have 400m for some parts of my system for the farm.

I also have designed another with a 300m run, it'll be installed soonish ....

It's not really any different to say the required for underground grid power for lots or areas now.

It does add some extra cost to the system with the long cable run, but arrays fairly far away help with aesthetics which some people want. #just saying
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Re: Hi from SA South Coast

Postby Gordon-Loomberah » Thu Jan 05, 2017 10:32 am

Indeed it can be done, and I'm sure you used suitable X-sctional area cable David, but for the system in question I'd suspect it is undersized for the demands about to be placed on it.
If it needs to be replaced, 300m of 25mm^2 or larger + conduit costs quite a lot!
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Re: Hi from SA South Coast

Postby amongstmyselves » Thu Jan 05, 2017 4:08 pm

Running new cable would be a big issue as there are retaining walls etc to deal with now. Keeping it all within the house seems a better option. I might still use the line back to the current shed for lighting and power as this will become a storage and gardening tools location.
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