Solar Power

[blynk]

Is it a good time to get solar power? Or is it likely that in the next 5 years they will bring out affordable batteries that will be able to store power rather than sell it back to the grid?

Kiwibank have a Sustainable Energy Loan, that if you put the cost again a home loan, they will pay back $2000 over 4 years.
So if the cost is $10,000 @ 6% and the loan was interest only, then that is the equivalent of pay no interest (4 years of Interest Only payments = $2184).

My wife is also home during the day for at least 2 weekdays, and potentially there could be another baby, which would make that 5 weekdays.

But I would hate to purchase it now, only to find that there is some great advancement in solar technology that is about to hit the consumber market.

[Ab]

Got a power bill for the Dec quarter: negative 400 dollars. So yeah, solar fan here.

[CCS]

Ab, have you paid off the cost of the solar installation? Or did the house come with it already?

[blynk]

What is the buy back like in Oz?
$400 in Dec sounds pretty damn good.

For me, again based on 6% interest rate, and the $2k from Kiwibank, it would be paid off in $10 years at $100 per month. And I would hope that most of that would come from power savings/buy back

[DrTiTus]

There are no great advancements in solar panels AFAIK, so the risk is only in your battery bank (because graphene), and the total cost vs money saved.

If you don't get batteries you're a cheap source of power for the grid - the buy back rate is about 25% of retail IIRC - certainly not 80-100%. And who needs that much electricity during the day?

If you use minimal electricity (~$100/month, with gas for water/heating) then the right setup could potentially get you off the grid, but if you're a heavy user ($400+/month with electric hot water cylinder and bar heaters), you won't be able to give up the grid entirely.

A good first step is a power monitoring solution: identifying how much you use, which appliances are using it, and how much you could potentially save by doing things another way. If you don't know your power profile you won't know your requirements.

[blynk]

Thanks Dr. I wouldn't be going batteries as I know that that is not worth it at the moment.

Yes buy back is stupidly low, and that wont change while National is in charge, but the likelihood is there will be someone home during most days.
I am planning on getting instant hot water (gas), but everything else is electric.

But maybe it will be a bit pointless getting the gas hotwater as that would take away some of the savings.

[StN]

Dr T - thoughts on batteries vs hydrogen fuel cells from electrolysis and some spare combustible gas for water and cooking? I saw this setup on Sommes last time I was there. They only spin up the genni once a week to test it now.

[Ab]

Originally Posted by CCS

Ab, have you paid off the cost of the solar installation? Or did the house come with it already?

Fortunately house came with it.

[MadMax]

do you think it added to value of the house? how much influence did it have on your purchase?

[Golden Teapot]

This doesn't stack up economically for our home by a long way. I'm sceptical this makes economic sense for many people really.

It's also not really in the national interest to let people use the grid as their battery - just look at the mess Germany got itself in to.

Viewed as a hobby then I get the appeal.

[blynk]

My estimates are that it pays for itself in 10-11 years and has a life of about 25.

[MadMax]

for the super long term, yeah it makes some sense. great if you've found the house you intend to live in for the rest of your life or at least the next 20 years. great if you're slightly green bent.

[Jodi]

If the 2nd hand battery market for the tesla takes off, then the price for battries will come down lots.

If

[blynk]

Yeah, thats why I was originally asking as there may have been something in the market about to be released.
I think the Tesla stuff will be a while before it drops to a reasonable level.

I also figure that once the solar power is set up, then it would "just" be a change of the inverter and the addition of the batteries.

[crocos]

Should really have batteries, otherwise you're charging to the grid at a low rate during light usage time, then pulling from the grid during your heavy usage time. Just need to work out the cost difference vs how long it'd take to pay off the batteries to see how worth it (or not) it is though.

Lead acid would be fine - cheaper than LiPoly for the same capacity, doesn't expire as long as you keep them topped off with fluids.

[Juju]

My work will be dumping a lot of 12v, 150Ahr monobloc sealed lead acid batteries this year - are they any good for solar power installations?

[Delphinus]

Originally Posted by Juju

My work will be dumping a lot of 12v, 150Ahr monobloc sealed lead acid batteries this year - are they any good for solar power installations?

Very likely. I might be interested in a few too.

[StN]

* cough *

[blynk]

So its one or the other? You are either connected to the Grid or you are on batteries.

A very brief read seems to indicate that the cost of the batteries and their shorter lifespan would mean it is not a better option. Or at best it is the same as being on the grid.
But I would clarify the costs when I get someone to come out and quote

[crocos]

Originally Posted by blynk

So its one or the other? You are either connected to the Grid or you are on batteries.

From a purely engineering POV, I don't see why that would need to be so. Once your batteries are topped off, start supplying back to the grid / batteries are flat, draw from the grid (but not to charge the batteries).

[spigalau]

The old man has been looking in to installing these at the lodge.



Combines Solar & Wind in to one generation platform. But comes at a cost $$$$

[blynk]

dumb question, but does a 2kW unit supply 2kW/h? Or is it not like that.

I have a years worth of history of my energy usage and I know that for a given hour I used a certain amount of power.
So I can work out during daylight hour, how much I use on average but need to know how to relate to the size of the unit I need.

[Deadmeat]

Originally Posted by spigalau

Combines Solar & Wind in to one generation platform. But comes at a cost $$$$

I kind of want to know why between the first pic and the second pic, the generation triples, the number of solar cells triples, but the number of wind turbines only doubles. What got more efficient between pic 1 and 2? How much is the wind actually contributing?

[CCS]

Originally Posted by Deadmeat

I kind of want to know why between the first pic and the second pic, the generation triples, the number of solar cells triples, but the number of wind turbines only doubles. What got more efficient between pic 1 and 2?

Magnets.

[DrTiTus]

Originally Posted by blynk

dumb question, but does a 2kW unit supply 2kW/h? Or is it not like that.

Watts (joules per second) are a rate of energy production/consumption, like how speed is a rate of moving (metres per second). If you have a 2kW solar panel (2000 joules per second), and it runs for an ideal hour, you get 2kWh of energy. Note it's kilowatt-hours, not kilowatts per hour. You multiply the rate by the time to get the energy (like speed by time gives you distance).

If you're feeding the grid and have no batteries, you don't need to calculate much - whatever panels you buy will feed the grid as best they can, and that's the end of it. When they do, they do, when they don't, they don't.

If you're trying to have a proper solar system (one that keeps going when the grid goes down), you need to think not only about the panels, but the size (and number) of batteries, as well as your inverter specs.

Batteries are a bit confusing, because they are rated in Ah (amp-hours), over a specified period (usually 5 or 20h depending on the application of the battery). To use Juju's old 12V 150Ah batteries as an example, assuming it's a 20h figure, the batteries could provide 7.5A for 20 hours before going flat. Power = volts * current, so that's ~90W per battery for 20 hours. You might be able to get 200W for 8 hours. You'd probably want at least 6 of them in a modest setup. The more the merrier.

The more current you draw, the faster the battery will go flat - don't expect to get 150 amps (@12V = 1800W) for a whole hour from them. If you repeatedly draw too much current and for too long, your batteries' efficiency will drop drastically until they no longer hold charge. You've fucked the chemistry at this point, and they need to be reconditioned/recycled.

You also need an inverter that can handle your PEAK load. If you use the dryer (2.4kW), vacuum cleaner (1.2kW) and welder (3.6kW) all at once, you might need an 8kW inverter. If you are a conservative single person in a tiny house you might be able to get away with a 2.4kW inverter. I wouldn't bother with less than a 3.6-4.8kW inverter on a family home - if you skimp here, you're going to trip the safety and lose power whenever someone vacuums/welds.

Once you've added up all the costs, including replacing your batteries every 5 years, as well as installation (DIY = house burn down), you might find it's cheaper just to make a habit of using the washing line for drying clothes and wear a jumper and socks to keep warm.

From a green perspective, it is only recently that the energy produced by a solar panel in its lifetime became greater than the energy cost to manufacture it. Solar panels definitely have their place (remote huts/sheds, campervans, satellites, etc) but in a country where most of our electricity is produced from renewable sources (geothermal, hydroelectric), it's not so important (environmentally at least) for us to move away from the grid.

[blynk]

Thanks for the in depth reply.

For me, I am urban, I would not be going completely off the grid. Not yet anyway. Maybe that would be my Solar 2.0 in future.

Thats interesting about the peak load and trip the power, is that for both on grid & batteries?

[blynk]

missed the edit window...


So if I know that I did 2kwh in an hour (as that is what I was charged), it all depends on what the load was. So it could have been 4kw for 30mins, and a 2kw would cover half of that.
But that raises a question. If the power usage is more than the setup, does it need to take it all from the grid? or can it do half and half at the same time.

[MadMax]

no, a 2kw unit won't cover half of that. a 2kw unit will turn itself off if at any time you demand 4kw of power from it.

[Gijoe^]

whats missing from alot of things is the cost of delivery (line charges)
In Gisborne its so fucked up, the cost per kwh of delivery is equal to the cost of the power delivered. THus every kwh you save saves twice! the cost per KWH,

I want to do full off grid because we have such a large roof, battery storage is a thing tho, and they are expensive to keep and maintain and have limited life,
Id do a desisel backup genny too, because 50cents effective KWH is fuckin spensive no matter which way you cut it.

[Markh]

I think the idea of generating your own electricity is a very interesting one with many things to consider.

If going to a hybrid system of generating your own power and storing it to use but also being connected to the grid you would definitely want to shop around for the cheapest line charge. To work this you would need some power sockets connected to the mains and some connected to your inverter - maybe running the oven/stove from the mains so you don't need as powerful an inverter or as expensive a bank of batteries.

Battery technology is definitely a hindrance with the cost, capacity and lifetime problems.

Going with a system where you are connected to the grid and supply power to that grid - I'd look carefully at costs and what you would get paid for power supplied. I'm doubtful that this would really be worth it.

Going with 100% self generating and disconnecting from the national grid - I like the idea and there would be zero line charges. But this would be quite expensive and there would be a lot to do. I would look into changing all lighting to 12V DC to avoid wasting efficiency inverting power. In fact all power use should be looked at and minimised. This system would involve a very large capital outlay but would save thousands in power bills. I wouldn't worry about new battery technology on the horizon because the batteries bought today would have to replaced in a few years and that means you could change to better battery types if available when replacement time rolls around.

It would be worth considering solar water heating, that would reduce the power required for water heating. I'd rather go this way than pay for gas and supply charge.

[MadMax]

You'd get gas rather than run an electric oven. If gas isn't available, go for either the option of delivered bottle swaps or go the largest size your local gas filler allows to fill/swap your own. Also on a system that auto-switches between two bottles so you can refill one while the other keeps you cooking. These bottle systems are not expensive

[StN]

...or use some of the surplus electricity to power an electrolysis system to produce hydrogen, as I pointed to in the Callaghan link. This system developed at the former DSIR and trialled on Sommes Island is being sent to Pacific Islands as a test to see if they can provide enough grunt for a village at a time in relief situations.

[Golden Teapot]

How long do early adopters here estimate that they'll be able to avoid most of their true cost of being connected to the national grid?

I get it early on. It's not worth the drama of changing how the cost of maintenance of the grid is recovered from a handful of people for whom the fixed and variable charges used by power retailers don't work. Eventually this becomes a problem though since not enough money will be being collected and presumably then a transition to some sort of poll charge will needed.

The grid will have to cope with the same peak demand as now so the cost of maintenance isn't going to go away. As discovered overseas (or by thought experiment) everyone with a solar system wants power from the grid when there's been no sun for a while just the same as if they had no on-site generation.

Assumption wise I can see a five year bet as being safe, the same at 10 years; 15 to 20 years out though I do wonder. And, many of the cash flow signature arguments that claim money will be saved rely upon implicit assumptions like this (well, let's face it this assumption is going to be a black swan for most people).

I am pretty skeptical that money will end up being saved at the current price point unless some sort of parasitic free-ride can continue in the long term and abatement here has already started for those who were using the grid as a cost-free battery and so I think an argument based on a continuation of the free-ride is weak.

It's a great hobby though and I imagine getting a system myself at some point. I've the perfect roof with a 360 degree unobstructed view of the sky (we have a dodecagon shaped house built on the pinnacle of a hill - four or five of the roof segments would be perfect for panels).

I want the equipment costs to halve before I buy.

[MadMax]

https://www.youtube.com/watch?v=gq0f6FXjyMk

Dave looks at his 3kW home solar power system after being in operation for 18 months and analyses the results.

"use it or lose it"

[DrTiTus]

<3 EEVBlog

[MadMax]

haha yeah he's awesome and quite entertaining.

[[LvN]N3misiS]

Originally Posted by DrTiTus

<3 EEVBlog

yep

https://www.youtube.com/watch?v=AO-vbzLPwSc

[crocos]

My fav is this one:
https://www.youtube.com/watch?v=hoqF3gjLIyI
So many facepalms

[Beccara]

Strangely find myself agreeing with GT here, At some point solar users will be handed a grid bill, The grid takes an awful lot of money to run and infact a high solar usage grid will suffer far more stresses as abnormal loads come on and off the main grid opening options for a cascade failure. At the moment the system operator uses a large amount of back data on usage and the environment to in effect predict what loading the next 5/30minute window will have and ask generators to be prepared for that load, Just because a generation offer is in place for the time window doesn't mean it's able to be spooled up at the drop of a hat

[blynk]

Do you mean grid operator I.e Vector
opposed to the power supplier-Mercury Energy.

Right now, I pay 95c per day as a daily rate under "Energy Charges". I assume this means Mercury
I pay 94c per day to Distribution and Transmission, which I assume is Vector (or someone). These charges are not going to change, I still will be paying that every day, so why would I pay more?
I also pay the variable part which for "Vector" is another 6c per KWh. Yes this one would drop.

As for abnormal spikes, they would still be able to use historic data to know when spikes are due to hit, and its not like its a sudden take up of solar that would fuck them over.

My assumption would be IF they did introduce a Grid fee, then there would be some set payback rate which would counter that anyway