diy solar

diy solar

Tired of pumping energy into the grid

More to do with me being cheap.
12V needs big expensive 'special' wires
Subjective. Bigger cable costs more money but for the distance and lifespan it’s not expensive. On the grand scale 20-year view it’s not a lot of money.
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48V I can do everything with cheap 2.5mm twin used for normal house wiring
If it’s safe and it works for you, great!

On the <2000W scale 12V is acceptable and has some advantages in lighting, being able to buy something locally quick to fix an issue at 12V is easier.
24- and 48V offer advantages most beneficial to higher demand systems.
 
More to do with me being cheap.
12V needs big expensive 'special' wires.
48V I can do everything with cheap 2.5mm twin used for normal house wiring (10cents/m).

I'm cheap too, and spending an extra $2k on technology I've never tried before just to save money on cables seems like a false economy. Besides, while testing the tech, I can just leave the ovens out of the circuit.

Your reasoning is sound, and I'm not arguing with that, but 48v on 3v cells means diving in with 16 cells right away.

So I'll go with 8 cells and a 24v inverter. If I want to double up later I'll build an identical battery and put it in parallel with the first.
 
Your reasoning is sound, and I'm not arguing with that, but 48v on 3v cells means diving in with 16 cells right away.
Cost me $1000 for 16x second hand 200ah CALB cells inc BMS.
I get 6-7kWhr out of them.
 

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Cost me $1000 for 16x second hand 200ah CALB cells inc BMS.
I get 6-7kWhr out of them.
I'm buying 304Ah cells for AUD250ea with shipping right to my home. I'm hoping they will be close to 1kwh each.
 
That's an interesting article - love the Guardian.

But if too much electricity is being pumped into the grid by domestic solar arrars, why are they still building solar farms like this one in Merredin, WA?

Since writing this I have read an announcement that they will be adding a battery to the Merredin Solar Farm. The technology looks quite interesting, for large scale projects:

 
I still have at least 6 weeks before any cells arrive, so feeling bored, I thought I'd add a financial aspect to the power and energy audit, making it a power, energy and financial audit.

I've just rediscovered that the grid-tied Fronius inverter, connected to the panels on my house roof, stores the total energy generated over the life of the system. I can combine that with the data I already have on energy exported, to find the total amount of energy I have consumed from the panels.

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So over the 1243 days the system has been in operation. it has generated 38,861 kwh. Of those 23,328 kwh were exported while 15,553 kwh were consumed locally. At local prices prevailing when that power was consumed, the saving was $4,459. Add to that $1,381 taken off bills for export credits, the total saving is $5,840, which is more than I paid for the whole system. I am quite surprised at the shortness of the payback period on the solar only grid-tied system.

Anyway, the figure of interest for the current exercise is the $2,959 spent on imported energy. That figure alone tells you that the batteries, which have a shorter expected life than the panels, will have to work harder to pay for themselves. Making it even harder, some of the imported energy came in during the day when there was cloud cover. This whole thing would be so much easier if the batteries were in the same circuit as the house panels, so they could just cut in and cut out as needed, but the regulations make that very difficult.

Nevertheless, if I contain the costs on an eventual 16 cell system, I should be able achieve crude cash payback within 5-6 years.
 
At our local 18c/kWh that’s roughly $7000

It’s nice when it crosses over and becomes “free”

With basic numbers and not accounting for some obvious things that are still significant but small in scale, your system doubles your money in 8 years- not a bad investment.
 
Cool thread. Thanks for joining the forum and sharing your thoughts & experience @mcart117.

I'm a big fan of systems which operate without being grid dependent. Many folks believe the grid will always be providing power with minor interruptions every now and then. I'm not one of those folks. I have designed a parallel system which will power fridges, freezers, lights and some cooking appliances indefinitely regardless of grid power.

Post 32 mentions your microwave. My microwave has 2 power numbers, cooking power = 1000 watts, power consumption to achieve that 1000 watts is 1600 watts. Your microwave may have similar numbers to consider.

Another point I would like to share is that folks often chat about air conditioners, stoves & water heaters while the value of foods in fridges and freezers are rarely discussed. When the grid is down for X number of hours, much or all of that food becomes trash or gets donated to the compost bin. If I loose the contents of a freezer, I will be chucking $500 to $1000 out the window.

There's some food for thought.
 
First of all, hello to the forum and thank you for having me on board. I don’t think I’m a typical member. I am not a DIYer. I did physics at school so I understand Ohm’s law, but I am not practical. I am here to overcome the ridiculous constraints of Australian regulations and the profiteering of local solar contractors, and Tesla.

There are lots of things I don’t like about my current setup. First of all I have 6.5 kw on the roof but Australian regulations only allow me to pump in 5kva, so on a sunny day that’s 1.5kw of power going to waste. Second, in the summer, even with the 5kva choke, I am pumping over 20kwh a day into the grid for 7c/kwh, but when the sun goes down I pay 55c/kwh to get it back. Third, when the power goes out, the inverter turn right off, and I am left without power, even if the sun is shining.

So I’d like to store my surplus power, I’d like the battery in the circuit before the inverter so it can suck in the full 6.5kw from the roof, I’d like the battery to absorb power from the panels and power the house during a power cut, and I’d like to spend less than the AUD1000/kwh quoted by local contractors for a Tesla powerwall.

I’ve noticed from EV enthusiast websites that new EV batteries sell for under AUD200/kwh. Some people are powering their houses with 2nd hand EV’s; they seem to be mainly in the US, but it’s an option I’d like to explore. And Alibaba sell 3.2V 280aH “solar storage system” cells for around USD120-200/kwh.

So I’ll read what other people are posting, and then I’ll fire out some questions.
This looks like an older post and I am hoping that this discussion can still continue, so bear with me if I go on a bit!
First though, I feel supported in that I have been dogged by my power being "robbed" by the energy companies giving a totally new meaning to the term "daylight robbery"!
I now understand that utility companies have profit maximization algorithms which react to conditions of weather, usage, grid "greed" needs and other conditions (paranoid? Yes I am!) All this without a single sentient being witnessing it and therefore feeling some guilt.
I like the idea of creating some loss
 
Why?

Removing/reducing your PV exports just means it needs to be replaced with energy supply provided large power generation companies, most likely coal power stations if you are in NSW. That makes zero sense to me.

But if you must then there is a setting you can make in the inverter's portal to invoke zero export if you so choose. It's in the Fronius DNO settings and you'll need your inverter's service level password to access it.

Feed in tariffs are roughly in line with the wholesale value of the energy at the time it is generated and represent fair value.
 
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