Help me make my decision for an off grid system. « Alternative Technology Assn Forums

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Help me make my decision for an off grid system.

(12 posts) (6 voices)

Started 8 years ago by jimmyg
Latest reply from David

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jimmyg
Member

We are in the process of building a new house on a property in the Southern Highlands of NSW. The cost of grid connection is prohibitive so we are going down the off grid solar route.
So far I have three quotes for a 10 KWH a day system with varying costs and sizes.
One quote includes 4KW solar panel array a 5KW Selectronic inverter and 1380 AMP hours flooded LEad acid (raylite) battery bank.
This system is around $36000 Installed.
The second quote comes from a Kit company for DIY install System with 6KW of Panels 1230 AMP hours AGM Battery Bank and a 6KW Inverter/Charger for about $35000
The Third also has 6KW array but only 1000 AMP hours AGM battery Bank with a 5KW Schnider Inverter/charger at about 31000 Installed.

Should I be looking for a larger Solar array or Larger battery bank? Which seems to be the better deal and what else should I look for?

Thanks in advance

Posted Friday 14 Feb 2014 @ 7:57:58 am from IP #
franks
Member

Install allow $1k per kW of PV array & $2k balance of system.
parts at retail costs..check out web sites for parts pricing..should be able to work out a fair cost.
keep in mind wholesale customers get 20-30% off retail.
I would say you source the parts and pay a installer $6k would do the trick..and you claim the paultry $3k of STCs
example

SMA SunnyIsland 5048 inverter charger $7k, 4kW PVs $3k, midnite solar 90amp MPPT charge reg $1.1k, sundry items $1.5k, battery 30kWh $15k plus $6k install labour = $33.6k less $3k STCs credits you offset..total $30.6k..I would allow extra $1k for travel and drinks..say around $32k any more your being ripped off.

I suggest do DIY install. pay sparky only for LV work and issue CES say $1.5k..save $4.5k..but get no STCs up to you..work out the same sneaky buggers know this.

Posted Friday 14 Feb 2014 @ 11:53:15 am from IP #
franks
Member

I should say spark mate & I install system for $30k no STC and issue CES..you provide food and board LOL

Posted Friday 14 Feb 2014 @ 12:10:56 pm from IP #
sun2steam
Member

jimmyg, what you call 'AMP hours' does not mean anything unless you also give the voltage.

I think it is best to convert all storage systems into kWh.

example:
12V battery with 100 Ah(that's what you called 'AMP hours') =12*100 Wh = 1.2 kWh
(as lead batteries should never be discharged below 50%, the real capacity is 0.6 kWh)

Some other battery types allow a higher discharge than lead batteries.

One other thing to consider is that flooded lead batteries need to be serviced regularly. So you must regularly check the level and maybe even the battery strength and fill the batteries up. Lead gel batteries are more user friendly in this regard. They are sealed and do not need service.

Posted Friday 14 Feb 2014 @ 11:13:06 pm from IP #
Greg
Member

jimmyg, for a cost comparison have a look at the dedicated Jaycar site here -> http://www.jaycar.com.au/pt_packs_offgrid.asp

10kw System
4kW solar
6kW inverter
2700Ah batteries
Total $34590

Equipment is from Rich Electric eg here -> http://www.rich-electric.com/?page_id=501

Posted Friday 14 Feb 2014 @ 11:19:25 pm from IP #
axess
Member

Hi jimmyg,

Good on you for taking the RAPS route.

Since you are building a new house you have a good opportunity to plan the placement of the components particularly for future servicing/replacement requirements. And best wiring routes of course.

If the panels are going on the roof for example then appropriate structural support is obviously necessary, plus easy and safe access for servicing and future upgrades is good to think about now when you are still young and fit.

I notice there is no mention of any sort of generator back-up connection for those unforeseen circumstances.

I hope your "spark mate" is willing to help with warranty issues and urgent service call-outs. Mates have a habit of falling out over ongoing building type issues. A well established, preferably local company would offer this type of support as part of its price.

Good luck with your project.

Posted Saturday 15 Feb 2014 @ 12:05:05 am from IP #
jimmyg
Member

Sorry I should have mentioned that it will be a 48 volt system. And yes it will have a generator back up probably a 10KVA Himoinsa. My question is whether I should opt for a bigger solar array or focus more on a bigger battery bank. The southern highlands have similar weather conditions as Canberra (maybe not as extreme but in the ball park) to give an idea of our area.
Our house is passive designed air tight so heating and cooling will be at an absolute minimum if at all.

Posted Saturday 15 Feb 2014 @ 2:09:40 am from IP #
jimmyg
Member

Also we are looking at placing the panels on the ground away from the house on the North side to get better efficiency. The inverter and batteries will be housed in a dedicated building behind the panels and 240V cabling run back to the house.

Posted Saturday 15 Feb 2014 @ 2:11:46 am from IP #
franks
Member

PVs being so cheap..better spending $2k extra on 2kW of PVs and not spend $5k diesel autostart 4kVA genset,
Sparky with grid install experience, can easy do LV work on a DIY stand alone off grid install.
My setup 6kW PV arrays, (PV array 3kW DC 3kW AC coupling) 3kW Grid inverter, 3kVA inverter charger, (Max power demand 4kVA nite 7kVA day) 28.8kWh battery storage..with sparky & CES total cost $22k. with no STC discounts,

SMA sunnylsland & sunnyboy inverters, midnite solar mppt 80 amp charge reg, BAE Gel Batteries, NESL 190W monos PVs

Posted Thursday 20 Feb 2014 @ 8:54:52 am from IP #
David
Member

franks said:
PVs being so cheap..better spending $2k extra on 2kW of PVs and not spend $5k diesel autostart 4kVA genset,

A generator will run if there is a bushfire and the PV will not work, smoke obscures the sun, if living off-grid one must allow for a situation like this, not to do so is foolhardy. one must always think of the worst possibility and that's one of the worst it's also one time you need the continuous power especially if you expect to be able to stay and defend.

Posted Sunday 23 Feb 2014 @ 11:30:58 am from IP #
franks
Member

Indeed, still have a 3kVA manual start genset, but in 18 months its never been used.

Posted Sunday 23 Feb 2014 @ 10:10:15 pm from IP #
David
Member

franks said:
Indeed, still have a 3kVA manual start genset, but in 18 months its never been used.

Haven't had a Bushfire to deal with then, electric pump/s for fire fighting can pull heaps of current particularly when to get both the pressure and volume one uses several high volume relatively low pressure pumps in series to get both volume and pressure together, that sure eats up current in a hurry. I'll take auto-start any day thanks that way you don't have to think about it, it will be there when you need really need it, provided of course some basic servicing is maintained.

Posted Tuesday 25 Feb 2014 @ 11:49:18 am from IP #

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