Offgrid Newbie - applicance use Q

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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Thu Aug 25, 2016 5:13 pm

Ok thank you, I didn't really understand the part about the grid connect. I will ask him about that. Probably prefer to go the bigger just in case.

I'll also ask more about the batteries. Thanks for your help.
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Re: Offgrid Newbie - applicance use Q

Postby offgridQLD » Sat Aug 27, 2016 10:06 pm

12kwh could be a tad small for the battery capacity if you want to minimize or eliminate generator usage (just going on what the typical house would use) We run 20kwh battery. Most nights we are only using around 15 - 30% of that. Though when we have ad bad weather we have seen in hover around 40% SOC for a few days. hasn't got low enough to need a generator yet over several years.

So I feel 20kwh is a good size for the average house.It will still be sufficient capacity as the battery starts to age over time and say 20% of the banks capacity is lost and your living with a 16kwh bank after x amount of years deterioration.

Though some system designers like size there banks to wring every last kwh of capacity out of the lithium battery banks to try and make it the most cost effective (kwh out pr $ spent over it's life ) On paper this sounds good but in practice. I'm still not sold on it and prefer a bit of breathing space.

As mentioned there isn't much you cant run off grid if your inverter is big enough. We run several split system AC units the house has all the mod cons dishwasher, vacuum, coffee machine and so on. I run machine tools in my shed , lathe, 4 ton car hoist, welders, plasma cuter, compressor 15 and 20A units.
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Tue Aug 30, 2016 3:34 pm

Thanks for the replies. I will talk to the company with my new questions.
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Re: Offgrid Newbie - applicance use Q

Postby Bman » Sun Oct 16, 2016 3:13 pm

So do you have an outcome yet mrsbobby?
Your scenario is very similar to what mine will be when we move, with the added problem of not knowing our power usage in the new place due to it it being 2000km further south than we currently are. We are going from a hot North West Qld climate to S.A. We currently use the A/C quite a lot (my wife was in Canada for 3 years prior to coming to Qld) but envisage a lot less use, if any, in SA due to the house having 300mm stone walls with 4m high ceilings.
We have been quoted $100000 to have the power connected from 500m away.
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Mon Oct 17, 2016 10:44 am

Hi Bman,

Well we have chosen a system and paid a deposit! Unfortunately it's been really hard to learn much about being off grid from online research. I posted this question in a couple of forums and no one really answered my question. The installers you talk to obviously skirt a bit around it, but we have gone with a fellow in Brisbane who is friends with my cousin (who works in energy industry) so have more confidence that he is being honest and reliable. We didn't know anyone off grid so it's been hard.

We have gone with 6Kw array of solar, 15KwH batteries and 8.5kw inverter. We'll see how we go with that. We have reliable diesel back up in need. We are very hot and muggy in CQ but we generally don't use a lot of a/c, but with a baby due in Dec and a toddler, lets hope we can cope. I would say your climate is going to be a lot different down there, you might need heating more than cooling!

That seems a lot of money to have the power connected! We had to come approx. 2.5km and the job total was $102,000 but we only had to contribute $35,000.

There was a fellow who posted a couple of replies to my Q above that was helpful and said I could contact him with any questions (he is an installer and I think he is based in VIC). I will go back to my messages and find his contact details and message them to you.
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Re: Offgrid Newbie - applicance use Q

Postby Gordon-Loomberah » Mon Oct 17, 2016 11:28 am

Do you know the specs on your AC? It might be worth considering adding a new small 2 - 2.5kW unit (usually a lot more efficient) to just cool one room, rather than running one large unit for the whole house.

You can add more panels if you find 6kW isn't enough, but I managed to average near 12kWh/day over winter, and more in summer with a bit over 4kW of PV and no generator use for over 2 years, with a 21kWh LiFePO4 battery.

What sort of battery did you decide on?

Winters should be much easier for energy management in CQ, as we have a lot more winter cloud here.
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Mon Oct 17, 2016 5:09 pm

We only have two small box air cons at the moment, obviously we don't use them unless we absolutely necessary as we have to run the genie to use them currently. Therefore we would look at getting something more energy efficient later if we need too.

Yes I thought we would start with the package we have and panels should be easy enough to add to if required.

The batteries we are getting are Enopte Power Block Lithium battery blocks. The are LiFeP04. I don't really know what to quote when people ask me this!! I'm not sure what brand the actual batteries are as this guy imports them and packages them into blocks. He probably did tell me as some point.

I will report back after we have had the system installed and used it for a period to see how it works.
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Re: Offgrid Newbie - applicance use Q

Postby tom rickard » Sun Oct 23, 2016 10:59 am

I wouldn't worry about the size of your battery bank. If you already have a generator and don't mind running it for a couple of hours at a time here and there it is no problem to run it to charge your batteries when they get low.

I have 3kw or PV, and did a costing on getting another 3kw (which would eliminate any generator requirement for us with an average household usage of 12kwh/day), or running our existing generator to cover the winter shortfall, and it was around $3000 for the panels/wiring/charge controller upgrade, vs. $150/year for diesel.

Just keep track of how much diesel you use for the first year, and your decision on more panels will be easy.
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Re: Offgrid Newbie - applicance use Q

Postby offgridQLD » Sun Oct 23, 2016 11:52 am

There is a cost to the earth and your sanity listening to a motor scream away to great energy.

Though I am very aposed to generators.

On our road there are several offgrid homes and slowly people are taking advantage of low pv prices and upgrading there systems.

Most likely doing away with old tower pc' 50w downlighting double door fridges , rear projection TV's and so on from 10-15 years ago and replaced them with modern alternatives has lightened there load.

So it's a gloomy day today in my area as I type this and I can hear the clock tick across the room, wind in the trees and birds outside.

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Re: Offgrid Newbie - applicance use Q

Postby tom rickard » Sun Oct 23, 2016 3:04 pm

I'm not a huge fan of the generator running either. With a 15kva generator (the size the OP said they had), they would be able to fully recharge their 15kwh LiFePo4 battery in an hour. You just need to pick a time during the day when there is other noise happening (eg, preparing tea, morning mayhem when getting ready for school).

It's not like you leave the generator running all day, ours goes on for an hour or so every 2 or 3 days at a time when noise isn't an issue, for around 3 months of the year only.

For us it simply came down to a cost issue. If you don't already have a generator, it is a different story.

As usual, technology marches on, a 10kva multi-fuel turbine generator for $10k that makes less noise than a R/C aircon compressor is on the cards, and in my opinion will tie in well with a smaller energy storage to create a cost-effective system. I definitely wouldn't be over-investing in existing infrastructure.
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