Offgrid Newbie - applicance use Q

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Offgrid Newbie - applicance use Q

Postby mrsbobby » Mon Jul 25, 2016 10:23 am

Hi there,

We have a rural property in Central Qld and are getting some quotes for off grid solar as opposed to mains connection ($35,000 + connections etc). We have a donga/shed set up which is all wired professionally etc.

My, probably dumb sounding question, relates to appliances that people use when they are off the grid. Some of the companies that we have been talking to suggest that even basic appliances like a vacuum cleaner are borderline with out generator backup. We have a large diesel generator (15kva) that we use now, so that will be fine anyway, but I am wondering what other people use/go without with a complete stand alone system.

We already have gas cooking and hot water and a powerless septic so no power required for those.

So, do off grid people use air conditioners (if so, what type as we currently have 2 box air cons, mainly only used for day time kids sleep), Thermomix, hair dryers/straighteners, fan heater (just for shower time), chest freezer, toaster etc??!!! Or are these things we have to cut out?

We did a load calculation sheet and they estimated we need 9.14kWh rounded up to 10 kWh. This includes a few power tools now and then. If welding we have a stand alone welder/generator to use.

For some info, this is the details of one of the quotes we received in February:

12 x Solahart REC255PE solar modules – 255w 10/25yr warranty
1 x SMA SB3000TL20 (3kw AC) solar invertor
1 x SMA SI8.0H-11 8kw/48v battery invertor Sunny Island + remote control
Manual plug in point for generator (although we would prefer auto start)
24 x BAE Secura deep cycle – 3000cycles @ 50% DOD 6 PVV 900 (2v, 729Ah @ C10) batteries
plus all associated bits and pieces & installation
$37,388

Does this sound reasonable? We are getting a couple of other quotes at the moment.
Thank you for your patience!
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Re: Offgrid Newbie - applicance use Q

Postby Gordon-Loomberah » Mon Jul 25, 2016 10:56 am

Welcome to the Energy Matters Forums Mrsbobby :)

If you have a suitable inverter and battery, there is no problem operating large loads in an off-grid system. I regularly use 2.4kW power tools- saws etc, MIG welder, microwave, induction cooktop, vacuum cleaner, dishwasher etc, sometimes several of the above at the same time. I currently have a 7kW inverter, but even with the 3kW inverter I had a few years ago, using the above appliances separately was no problem.
I only use a small generator for battery charging in cloudy weather, as I have air and water pumps that must run for aquaponics systems, which represent a significant amount of energy usage, almost as much as we use in the house, or significantly more in summer when I run a large (>2kW) water chiller.

You probably should think about getting a quote for Lithium battery rather than the Lead-acid, and perhaps for a larger PV array to reduce generator use in cloudy weather.
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Re: Offgrid Newbie - applicance use Q

Postby dax » Fri Aug 19, 2016 10:06 am

We are off grid, have been for decades and a few year ago switched from lead acid to liffepo4 storage. The change has been dramatic and we now run the entire house on 240v, including freezers, fridge and induction cook tops using 2 inverters on the 3 house circuits. On really hot clear days, we can run a portable A/C for most of the afternoon and most days a vacum cleaner. We have 3.5kw of 24v solar, 750ah lifpeo4 and in our mobile home we have 480ah lifepo4, 1kw solar and ruin anything we want from it, including hot water heating.

if you are going the lifepo4 way, it's important to get charge discharge regimes right and not use lead acid parameters, or you will stuff them within 5 years.
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Re: Offgrid Newbie - applicance use Q

Postby SandyP » Mon Aug 22, 2016 2:56 pm

mrsbobby wrote:Does this sound reasonable? We are getting a couple of other quotes at the moment.
Thank you for your patience!


Maybe message offgridCBR to find out who gave him his quote :

wind-solar-misc/topic6593.html#p48922

I realise costs will be different in rural / remote areas.
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Thu Aug 25, 2016 3:36 pm

We were recommended by a relative to a company in Brisbane (supported by an electrician closer to us) and now have the following quote which sounds much more reasonable:

An expandable system in a large cabinet with 12KWh battery (lithium) / 8.5 KW Schneider Inverter / 6KW Solar PV system (Zeus-Apollo). Auzi-Max monitoring program.
Price $24995 (inc gst) installed, subject to site inspection.

Do you agree?
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Re: Offgrid Newbie - applicance use Q

Postby Gordon-Loomberah » Thu Aug 25, 2016 3:47 pm

Price does sound more reasonable, assuming the equipment is all of good quality.

Does the battery have a management system - high and low voltage protection for battery and individual cells?

Do you have any details on the battery? Is 12kWh it's total or usable capacity, and to what % DOD?

Can the Schneider inverter also charge the battery, IE is it an inverter-charger? What specs/model is the charge controller and inverter?
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Thu Aug 25, 2016 4:03 pm

Yes so the package includes the AuziMax Energy Management Solution which provides performance info on the solar panels and the batteries, and can remotely stop/start equipment.

The batteries I think have a usable capacity of 10kWh, they are LiFePO4. 80% DoD for 5000 cycles?

The inverter is a Schneider XW+8548E New Conext XW + Inverter/Charger

Any thing else I should be asking? Thanks for the help.
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Re: Offgrid Newbie - applicance use Q

Postby Gordon-Loomberah » Thu Aug 25, 2016 4:32 pm

That hybrid inverter is probably a bit more capable than you need, unless you are considering connecting to the grid at some stage.
The 6.8kW continuous output should be enough to run multiple large power consuming devices at once.

Do you have a brand/model for the battery?
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Re: Offgrid Newbie - applicance use Q

Postby mrsbobby » Thu Aug 25, 2016 4:47 pm

There is the option of the Schneider XW+ 7048E inverter too which has 5500W continuous output.

If we go solar we won't be connecting to the grid as that would be over $35,000 + installation costs etc

I don't have the brand of the batteries actually. This guy sells them pre assembled in blocks - I have tried to attached the brochure but it's too big. It doesn't specify any model or anything, I know they are Chinese, but aren't they all?
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Re: Offgrid Newbie - applicance use Q

Postby Gordon-Loomberah » Thu Aug 25, 2016 4:59 pm

Why pay for a hybrid grid-connect inverter if there is no chance you will be connecting?
>>The Conext XW+ will cater for full off grid, hybrid, load assist in both AC and DC coupled scenarios...

The smaller model is also grid-connect capable, but would 5.5kW definitely be enough to cover any projected loads? It could save you $800, but you'd want to be sure it was going to be enough.

Yes most Lithium batteries come from China, but I think you'd want a recognised brand with a good warranty.
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