Question:
I own 1 acre (4000sqm) it gets lots of sunshine and a decent amount of wind. It’s a subtropical climate with sporadic wet summers and dry winters. Its in a rural area and we are three people. We don’t use aircon. But I will need to use tools often grinder, welder ect. $15000aud in our budget.
Answer (from Alan Johnson – Quora):
As many others have likely noted in similar threads, going off-grid is about being extremely cognizant of the amount of electricity you are using.
There are certain things in my off-grid home that we simply do not have. These include items such toasters, electric coffee makers, clothes dryer etc. Producing heat uses a LOT of electricity.
Large appliances such as hot water heaters, Fridges and Freezers can be run off of propane, however, modern off-grid fridges are being made now with highly efficient compressors and ….lots of insulation. If you live in a subtropical climate where you can rely on sunshine most of the year, you will likely not have an issue and can probably run a full size fridge and a freezer off a modest system. Hot water production is easily managed by a roof mount solar hot water system. Very effective, even in less than tropical climes.
So, if you are looking at one fridge/freezer, small clothes washer (without an internal hot water heater), small appliances, lights, a well pump, water pressure pump, computer(s) and so forth, off grid energy consumption is not bad. Here are some numbers:
My home is about 1400 sq.ft and features what i have just described without the electric fridge. Our daily requirements are about 40–60Ah on a 24v system. I suspect most people will be double this, likely triple with a fridge. This will mean you will use about 150 Ah, which is about 3.5 KwH.
To store sufficient power, you will need a good size battery bank. I would go bigger than initially thought to account for the occasional household addition. For this usage a battery bank of 8 6V golf cart batteries would be the absolute minimum in my opinion. I would probably go with more, and depending on where you are I might choose larger Surette batteries. Large and heavy, but lower voltage and likely more robust than smaller 6v ones. From a cost perspective in Canada, you should be able to get by with about $1,800 – $2,000 CDN in batteries.
I would choose a 3–4,000 watt inverter – add another $2,000 or so.
Solar Panels – Panels are fairly cheap right now. 200W 12v panels can be sourced here for about $350 per. In a warm climate with good sun, 8 panels will be sufficient giving you at least 5–10 amps of power per panel (assuming a 24v system overall). Basically two hours of ‘peak charging’ will meet your daily needs. After accounting for inefficiencies, clouds etc, you should be able to meet all your daily electricity needs with about 4 hours of sunlight.
Total cost is easily under $15,000.
