Noob Solar Customer

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Noob Solar Customer

Postby Becisme » Wed Nov 09, 2016 12:59 pm

Afternoon all,

So my boyfriend and I are building a 100m2 flat and a large (12mx18m) shed on 6 and a half acres 20km north of Canberra. The plan is to build a large (400m2+) house in about 4-5 years time. We will be going solar but despite all my 'google' research I still can't decide on whether to go on grid solar, on grid with solar and batteries, or completely off grid. Our budget at this stage is 35k-40k and our primary motivation is to save money on electricity bills long term.

Realistically once the house is built we will have about 6 people (including children) living under the solar system. We'll have reverse cycle air conditioning, and more appliances then I can list. You name it we have two! In addition, everything we will be running out there will be run off electricity. No gas or any other form of power (unless we decide to go off grid and we keep a generator for emergencies). Conservatively I can see us using around 50kwh daily. We do have the option of on grid as it is already run to our block, but we will need to run it about 180m up to the building envelope to connect it.

My big concern with going off grid is running out of power during the winter months. Canberra in winter is woeful as far as solar is concerned, and we will often go a few weeks where we get nothing but cloud cover. I just think for the amount we would have to spend on an off grid system to get us through the winter months it would actually make more sense on stay on grid (though very open to stories of encouragement and experience which suggest otherwise). In which case do we go batteries or no batteries? Based on the calculators I've used we would need at least a 7kw solar system with a 12kwh battery, and would rely on grid at least 20% of the time during winter. During summer we would have surplus which would feed back into the grid. That was based on a 30kwh daily usage (probably a little optimistic). Or do we go solar panels only and get enough that we feed back enough to the grid during summer to offset some of the costs in winter (I know they sell it back it us at around 20x more then what we get paid for it... bastards)?

The other big question is whether we build a system to cover what we will use over the next 4-5 years (probably more like 25kwh per day) and then expand the system once we build the main house.

Open to advise and recommendations on the above, especially if you happen to live around the same area or in the same conditions.

Thanks for reading!!
Becisme
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Re: Noob Solar Customer

Postby Gordon-Loomberah » Wed Nov 09, 2016 6:33 pm

Hi Bec, 180m of cable to supply a house with 50kWh/day will be quite expensive, and consume quite a bit of your budget.

Becisme wrote: Conservatively I can see us using around 50kwh daily.


An off-grid system to cover that sort of energy usage will need to be huge

Based on the calculators I've used we would need at least a 7kw solar system with a 12kwh battery,


That would be nowhere big enough in PV or battery for 50kWh/day for an off-grid system.

Average annual global solar radiation, eqyuivalent to peak sun hours, in Canberra is 4.83kWh/m^/day, which is only a couple of percent less than I get here, so a comparison with what I have may be useful. I managed a couple of years with no generator use, 21kWh of Lithium battery storage and 3-4kW of PV. However, when required, I could cut my use down to about 6-8kWh/day, with only 2 people in the house most of the time. In sunny summer weather I could use well over 30kWh/day.
In more recent times I have much greater energy use, minimum of over 15kWh/day, and even with 7.7kW of PV, I need to use the generator at times.

If you could cut usage to under 30kWh per day during periods of cloudy weather, you might get by with 15kW of PV and 50kWh of LiFePO4 battery, and some generator usage.
It will cost significantly more than your budget though.

I think just going with a smaller system for now and expanding later on when the budget allows would be a good idea. Grid connected with battery storage may well end up being the best way to go in your case.

Have you obtained a quote to get the power run to your house site?
http://gunagulla.com Loomberah weather and astronomy including live solar radiation intensity and UV + Gunagulla aquaponics, organic eggs and cherries
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Re: Noob Solar Customer

Postby Becisme » Wed Nov 09, 2016 6:44 pm

Thanks, that's really helpful. We haven't got the quote yet but that will definately be happening over the next few weeks or so. The plumber arrives next week to do his bit before we lay the slab. I dare say we'll get the power run up regardless and then the power is right there if we need it. Just based on the estimates of how much power we need I suggest you may be right in saying an off grid system is probably gonna be too expensive, and I'd love to say we'll actively be reducing our power expenditure, but with a young family that will end up with 5-6 adults in the house eventually, I'm realistic.
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