What is the best way to use solar panels?

I have installed a 4kw system. I chose 4kw because that was the best use for getting the maximum number of panels on the roof with the best aspect.

The price after the govt subsidy of $7931 ( the subsidy is for the first 1.5Kw) was $12,995. The installation also required two inverters (included in the price). The alteration to the metering system cost another $220.

I have a deal with Country energy where they buy all the electricity for 60c a unit and I pay them 19.62c a unit for the power I use. The deal is for 6 years.

The salesman was over enthuastic in working out how much I would make out of the deal. The sun would have to shine brightly all day every day to reach his objective. The meter tells the total amount that I feed in and another reading tells me how much I buy back. After a few months I will have better idea of the actual economics. Even with partly cloudy days since the installation I am producing more than I am using. The next big drought will at least have some benefit.

As electricity charges increase the profit margin will decrease however I think the system will have paid for itself well before then. At least I look forward to no electricty bills ever again.

Smurf1976 said:

Here's some figures...

Suppose that every single electricity consumer (household, business) installs a 1kW grid connected PV system. In Tasmania, that would cost just over $2 billion and would produce electricty worth about $12 million per year or 2.5% of the state's total electricity consumption. The panels have a realistic working life of around 40 years, with major maintenance (replacement inverter, at a cost of about $2500 each) after 20 years (assuming you're using high quality equipment).

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At that rate of return, we might as well just toss the banknotes directly into the furnace of a coal fired power station and save on the environmental footprint of manufacturing the solar panels.

Unless their is a dramatic increase in efficiency and reduction in price for solar panels, they will have little effect on the bigger picture for energy use.

Im quite interested to see the possible future of thorium nuclear reactors, considering Australia has one of the largest reserves in the world, and it is 200 times more efficient than Uranium.
In addition to this it breaksdown within a few hundred years compared to a few hundred thousand years, and the nuclear waste cannot be harvested as weapons.

I was speaking to a mate at work today, he is looking at buying a block but it has no essential services. We were discussing the different options for electricity.

Solar during most days but what to do at night?

Smurf in another thread mentioned pumping water up a hill using wind. I was thinking maybe he could use a solar water pump that pumps all day and then use this stored energy all night/cloudy days. Not efficient but I wouldn't think it would need to be.

Has anyone used or seen this idea on a small/personal scale?

Thanks

For a normal household situation where mains power is not economically available, the simplest option is to go for solar and batteries.

Solar generates power during the day, and yes it will do that even when it's cloudy, and charges the batteries in parallel with the load (via an inverter).

With the big reduction in panel costs, it's reasonably economic these days to oversize the panels such that the batteries reach full charge on all but the worst of days (in which case they'll recover the following day). The end result, as long as we're talking about moderate amounts of power, is a stand alone fully self contained system.

As for pumped hydro, it certainly works as an idea and on a large scale it's around 70% efficient at storing energy. We do have 3 large scale pumped storage operations in Australia (Tumut 3 (NSW), Shoalhaven (NSW) and Wivenhoe (Qld)) but it's certainly possible to do it on a small scale if you've got the right topography. That said, for a household system then I'd stick with batteries unless you've got an actual source of water (creek, river) so as to make conventional non-pumped hydro your major energy source (in which case it leaves solar for dead in every way).

For 99.9% of such situations, batteries and a few extra panels above that theoretically required is the way to go.

Smurf1976 said:

Indeed.

It may well be taxpayer subsidised, but from an individual perspective it is a very good return (tax free...) on a relatively safe investment that requires no ongoing effort. It just sits there saving me money.

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Here is an update after 4 years of use:
We started with 1KW and upgraded to 2KW a year later, when the 40c/KWh FIT came into force, thanks to the State Government of the Day
I kept a spreadsheet with all power bills since installation, summing up units consumed, exported, and charges/credits for each. The spreadsheet also tallies the units produced.

Results as per 12/09/2014, the date of our most recent power bill
Total units imported: 17,832 for $3,646 giving an average 22.4943c/KWh
Total units exported: 6,855 for $3,196 credit = averaging 46.6354c/KWh
Total units produced: 13,816, which leaves
Total units consumed: 6,961, saving $1,592 at the rate of 22.4943c/KWh for imports

Operating costs for meter upgrade and bi-annual service fees amounted to $598. giving a
Net Profit of $4,165, or 53% of the combined installation cost.

Not quite the 20% annual ROI, but even 13% beats bank interest hands-down.
I guess if we did the laundry at night or before dawn, we could've used less power during the day, exporting a few more units at 46c and importing them at night for 22c; the difference might run to $1/week, or may be nothing at all. So, let's not worry about could've should've would've... I'm happy with the results.

Just last week I experienced yet another delightful (>4 hours) power outage during my trading time. This has become an increasingly annoying and frequent occurence (sometimes several times a month and usually of similar or greater duration) these past few years.

The deterioration in service reliability, combined with the exponential increase in the associated power bills, has been increasingly frustrating me to the point where I'm seriously tempted to tell the suppliers to go FTSE themselves and ditch their pathetic service altogether.

Smurf1976 said:

...For 99.9% of such situations, batteries and a few extra panels above that theoretically required is the way to go.

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In your opinion, what type/s of battery would one typically choose for storage?

Thanks Smurf, much the same answer I came up with googling. He has already started looking for a block with a water source.

I have passed on your suggestions about renewable energy in the Nuclear thread to anyone who will listen

Thanks Pixel

I am looking at installing solar for our house. In addition to saving power bill, I want to have solar as backup for my trading computers.

Some questions if I may:
1. As blackouts often happen during a storm, I'd imagine that there is no solar electricity generated during a storm?!
2. How much battery storage will I need if I want to continue to use my computer, 4 monitors and modem running for, say 4 hours?
3. How much do battery storage cost? Do they need to be replaced regularly?
4. Any recommendations for Brisbane solar company?

Thanks

cynic said:

In your opinion, what type/s of battery would one typically choose for storage?

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There's three options that I'd consider depending on application.

LiFePO4 (lithium iron phosphate) = the current "state of the art" way to do it and "on paper" has a lot of advantages. It's a less proven technology, relatively new versus the others which have been around for ages, but can also be discharged a lot more heavily without damage when compared to lead acid. If $ isn't a consideration then LiFePO4 all the way....

Gel (lead acid) = old tech but a very "set and forget" option that doesn't really need maintenance. Main advantage over LiFePO4 is the very proven, predictable nature of them. They're heavy and so on yes, but they just work without much fuss. If it must work, and you're risk averse, then Gel is your friend.

Flooded (lead acid) = old tech, high maintenance and best avoided by anyone not keen on tinkering with things. But that said, if they're properly maintained then they'll last a very long time and can end up being the cheapest option. A lot of hobbyist / tinkering types love them for this reason. They're reliable as such, and cheap - as long as you don't mind having to keep them topped up regularly. They're definitely not a "set and forget" option and not well suited to being regularly moved around either (unless permanently mounted in a vehicle etc).

Stand alone household on solar = LiFePO4 would be the "modern" way but also the least certain in terms of lifespan. Gel or flooded lead acid are less risky financially in that sense, you can be fairly confident of their lifespan, although they're inferior as such.

Backup to mains = Gel or AGM would be the easy option. Or you could use LiFePO4 if you're keen.

Gel and AGM (Absorbed Glass Matt) are both variants on the same thing - a sealed lead acid battery. Gel is somewhat more durable but has a slower discharge / recharge rate than AGM. Hence the use of AGM in things like computer UPS' with a small battery designed to last 15 minutes while you shut things down etc. AGM handles such a rapid discharge better than Gel does. But if you were going to size the battery to keep the system running for hours then there's no such advantage - and in that case the longer lifespan of Gel wins out.

There are also other battery technologies, eg NiFe (Nickel Iron) but you're not likely to consider those for home use. They do have some applications however, and the primary benefit of NiFe is their very long lifespan - we're talking 25 years or so. Downside = expensive and inefficient. But they're extremely robust which is the good point.

Something that cuts across all of this is the type of battery itself. An SLI (Starting, Lighting, Ignition) battery (commonly known as a "car battery") won't last long if deeply discharged. It will work yes, but a car (or truck etc) battery will have a short lifespan if it's being deeply discharged on a regular basis. It's designed to provide a huge current for a few seconds to start the engine, then be immediately recharged. It won't like running your computer all day. In contrast, a proper deep cycle battery is the opposite - it physically can't produce the high current that a SLI battery can, but it will survive many, many more discharge and recharge cycles in a solar or backup power application.

So Deep Cycle is what you want in any application for backup power, solar etc.

There are also such things as "marine" batteries and various other things. Typically, they're a hybrid - designed to be sort-of deep cycle but still put out a lot of current to start an engine. Leave them where the name implies, on boats, and stick to proper deep cycle batteries for solar etc applications.

I'm running out of time now, but will make a post on backup power for trading etc computers in the next day or two.

In short though, YES it's quite easily doable and that applies regardless of whether you want to use solar or just store mains power in a battery for use during the blackout. It can be done either way.