yobarr wrote:

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.....,a 2kw system is a waste of space..

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 I disagree.

If 2kW is what you can afford, go for it. The % return on investment will be higher than a larger system because 100% of the solar output will be offsetting grid power.

If you can afford a larger system, face some east, some north and some west if you can in order that you maximise the offset of grid power usage when you use it most.

Cheers,

Peter

The first power that a solar system collects off-sets the power that you using at the moment and that you would otherwise buy from the grid. That bit is worth maybe 35c/kWh (reducing).
If you collect MORE than you are using at the moment, it is fed into the grid and is worth only 10 - 20c per kWh (ant that will reduce too).
A small solar system might then be worth 35c/kWh for all or most of what it collects.
As the system gets bigger, a larger proportion of the power collected is excess to current requirements and that excess is worth less as a total % of the collected energy.

Fixed panels collect most energy if facing north at the nominal angle to the sun of the latitude. BUT, they do not collect as much first thing in the morning as they would if they were pointing east. Same thing in the afternoon.
And since the best value comes from collecting as much as possible that would otherwise come from the grid, collecting that as a priority can pay better than collecting more and feeding it back to the grid and having to pay for some grid power first thing in the morning and last thing in the evening.

So, yes, a bigger installation is better, particularly as the cost come rapidly down and may well pay for itself, but any size is worthwhile and smaller systems can be very good value even if they don't create the excess that a larger system can. And as feed in tariffs reduce, the best value it to draw as little from the grid as possible, so with a big system, point some panels east and west.

Personally I don't think batteries are a long term viable storage system for households. The very big batteries do have value to stabilise the grid, but storage for grid use will be via pumped hydro and hydrogen. That said, there is an Australian developed house scale storage system now on the market that converts excess power to hydrogen and then converts it back to power when required. lavo.com.au/
Now that technology is scalable up and DOWN, so we might even see it in our RVs one day. :)
Cheers,
Peter

Whenarewethere wrote:

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I remember decades ago at work we had this 20 year old forklift. Built like a tank & it just kept going. Could lift about 15% more than its rating.

In the back as a counter balance it was powered by a handful of 2 volt flooded batteries, those tall narrow ones. A few times a year we topped it up with distilled water checking with a hydrometer testing electrolyte density device.

It just kept going, maintenance was easy. Those sort of batteries would be ideal for fixed locations. A fair bit of room & ventilation is all that is needed.

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 My daughter and SinL have an off grid house powered by about 3.5kW of solar and gas for heating.

Their batteries are these 2V wet cells.

When they were 9 years old, one cell failed. It was replaced for no cost under its 20 year warranty. 

Expensive when purchased. Probably weigh a couple of tons. Not the battery of choice for the RV.

This is half the battery system on a station we spent time on in 2008. 2V wet cells.

Cheers,

Peter

 

Peter_n_Margaret wrote:

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The first power that a solar system collects off-sets the power that you using at the moment and that you would otherwise buy from the grid. That bit is worth maybe 35c/kWh (reducing).
If you collect MORE than you are using at the moment, it is fed into the grid and is worth only 10 - 20c per kWh (ant that will reduce too).
A small solar system might then be worth 35c/kWh for all or most of what it collects.
As the system gets bigger, a larger proportion of the power collected is excess to current requirements and that excess is worth less as a total % of the collected energy.
That is absolutely true,but surely it is better to install a bigger system that eliminates the entire bill,than it is to mess around getting rid of 30% whilst still paying an  ever-increasing rate for 70% of the bill?
Fixed panels collect most energy if facing north at the nominal angle to the sun of the latitude. BUT, they do not collect as much first thing in the morning as they would if they were pointing east. Same thing in the afternoon.                                                                 Again,you are correct,with one of the biggest misunderstandings in the Solar industry being that "North is best". Most Australian households consume electricity at the start of,and towards the end of,daylight hours,with little use during the day.North-facing panels will generate slightly power during the day,depending on the season,but it is the "useable" power that is more important.East and West wins there.There is an inverter that allows installation of panels in 3 different directions,but we're getting a bit complicated there!

And since the best value comes from collecting as much as possible that would otherwise come from the grid, collecting that as a priority can pay better than collecting more and feeding it back to the grid and having to pay for some grid power first thing in the morning and last thing in the evening.

So, yes, a bigger installation is better, particularly as the cost come rapidly down and may well pay for itself, but any size is worthwhile and smaller systems can be very good value even if they don't create the excess that a larger system can. And as feed in tariffs reduce, the best value it to draw as little from the grid as possible, so with a big system, point some panels east and west.                                     Provided a decent sized system....6kw or so...is installed,it is possible to install Solar that generates more savings than are the payments on a loan taken out to purchase.
Personally I don't think batteries are a long term viable storage system for households. The very big batteries do have value to stabilise the grid, but storage for grid use will be via pumped hydro and hydrogen. That said, there is an Australian developed house scale storage system now on the market that converts excess power to hydrogen and then converts it back to power when required. lavo.com.au/
Now that technology is scalable up and DOWN, so we might even see it in our RVs one day. :)
Cheers,
Peter

Great post,Peter,and I agree that batteries effectively are a con-job unless,of course,there is no option,such as living "deep in the bush" where no grid supply is available.The storage capacity of many of the battery systems being offered is so low that they are of little use,other than helping the supplier to increase his bank balance! Cheers.

 

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-- Edited by yobarr on Wednesday 24th of February 2021 08:05:20 PM

Perhaps be satisfied that your installation may not be from "C.... and will probably last a lot longer than the current models on the market.

The other justification for a larger system is in readiness for the electric car that many of us will be driving soon.
"Smarts" are already available to switch excess power to things like the hot water service, when other needs have been satisfied and there is still excess power available. Much better value than sending it to the grid for a reducing return.
So in priority order,
1. run the normal household requirements. We already "load shift" when it is convenient (ie run the washing machine and dishwasher between 10am and 3pm when excess power is available instead of at 8am or in the evenings when it is not available)
2. Charge the car (if it is at home).
3. Heat the HWS (we already get all of our hot water via solar collectors for about 7 months per year and a lot of it for the rest of the year).
4. Send it to the grid.
Cheers,
Peter

The so called rubish 1.5KW solar system on my house actualy exports more than i use. I used to get a $25 credit in the summer time. But the electricity suppliers keep changing the rates & contracts to the point i now get charged. All of my lights are LED my fridge is an LG inverter type & uses very little power. Heating is free wood, hot water is solar. The only way now to reduce the cost is to double my solar system to export more. Be along time before i can afford an electric car, there cost & battery replacement doesnt add up.

yobarr wrote:

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Craig1 wrote:

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Yobarr, the high feed in prices will not give any discount on any power you use from them, so 7 cents to you, if you want to get something back from them, around 17% here in Albury. We only have 2kw system.

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Hi Craig...Not sure how much you know about Solar,but my system exports up to 28kwh/day AFTER my usage.My FIT (feed in tariff) is 20cents/kwh, so my system earns me $5.60/day AFTER haven given me FREE power all day long.ALL power used during daylight hours is FREE,and the money that I've earned from my exported power cover my nightly usage,and my daily supply charge.At the end of the quarter the power company can put tge balance into my bank,or I can let it accumulate until Xmas time,by which time I have around $1000 to buy essentials,such as beer. Cheers

P.S Without wanting to be rude,a 2kw system is a waste of space...I've got 1.7kw on my caravan! With residential Solar always you should fit a system that is around 6kw. Economies of scale mean that buying a 6kw on finance is cheaper than buying a 2kw system.Hope this helps?

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Unfortunately it is not always possible to get permission for as much solar as you want. I wanted a 5 Kw system got all the quotes and arranged with a supplier to fit it, but when it came to it my electricity supplier ( Origin) said no you can have a maximum of 2.7 Kw. Highly annoyed I rang them and said 2.7 is no good I want 5 Kw. their answer was that will involve upgrading the transformer outside your house we will send you the invoice. I have a 2.7 Kw system. Landy

DeBe wrote:

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My 1.5 Kw system was installed on 14-4-12. I actualy read my meter every week, so i know what it has produced & what i have used. Up to 9-3-20 the total solar produced was 18564 Kw. Total consumed was 10250 Kw. Total exported was 12662 Kw. Up to this date was only a 1.5Kw system so my reconing is ive exported 2412 Kw more than what ive used.

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 Hi Daryl....as close as I can calculate in my head,it took 2884 days for your system to generate 18,564 Kw.This means average daily generation was an earth shattering 6.4kw...My system averages around 28kw/day,over a year.On a good day I can get up to 50kwh,but a lot less on a cloudy day.The fact that have consumed only 10250kw in the time you've had your Solar installed shows that you use very little during the day,with average usage at 3.55kw...PER DAY.Most houses use waaay more than that,with one chap I know using 188kw/day.Your usage is low,which is why your export figure is greater than your usage figure at 4.4kw/day.Your average daily production is 6.4kw.....a GOOD 6kw system will average around 27-28kw/day over a year..There is little doubt that you have tried to do the "right thing",but you have obviously been misled.Do it once,do it well.Install 6kw+,or the biggest system you can fit on your roof,if space is limited.People who claim "We couldn't afford more panels" are delusional.The bigger the system,the cheaper it is,per kw.Solar costs NOTHING...it pays for itself.Cheers

-- Edited by yobarr on Thursday 25th of February 2021 01:56:05 PM

landy wrote:

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yobarr wrote:

Craig1 wrote:

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Yobarr, the high feed in prices will not give any discount on any power you use from them, so 7 cents to you, if you want to get something back from them, around 17% here in Albury. We only have 2kw system.

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Hi Craig...Not sure how much you know about Solar,but my system exports up to 28kwh/day AFTER my usage.My FIT (feed in tariff) is 20cents/kwh, so my system earns me $5.60/day AFTER haven given me FREE power all day long.ALL power used during daylight hours is FREE,and the money that I've earned from my exported power cover my nightly usage,and my daily supply charge.At the end of the quarter the power company can put tge balance into my bank,or I can let it accumulate until Xmas time,by which time I have around $1000 to buy essentials,such as beer. Cheers

P.S Without wanting to be rude,a 2kw system is a waste of space...I've got 1.7kw on my caravan! With residential Solar always you should fit a system that is around 6kw. Economies of scale mean that buying a 6kw on finance is cheaper than buying a 2kw system.Hope this helps?

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Unfortunately it is not always possible to get permission for as much solar as you want. I wanted a 5 Kw system got all the quotes and arranged with a supplier to fit it, but when it came to it my electricity supplier ( Origin) said no you can have a maximum of 2.7 Kw. Highly annoyed I rang them and said 2.7 is no good I want 5 Kw. their answer was that will involve upgrading the transformer outside your house we will send you the invoice. I have a 2.7 Kw system. Landy

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 Hi Dave...does Vic gave a Gross feed-in,or nett? If it is nett,your "problem" is easily solved.Cheers

I have two solar PE arrays on my roof. One is 3.2 kW, and has been there for about 11 years, the other is 4.6 kW and has been there for about 3 years.

At the time of the first array installation, the Govt was giving a very healthy rebate for 1.5kW installations. I opted for the 3.2 kW, even though the Govt rebate was effectively almost zero, because that size just about offset our average energy usage over the year (my wife is not energy aware in using appliances etc). A rule of thumb is to multiply the installed capacity (kw) by 5 and that will give you the daily average energy production (kWh) over the year. Our panes all face North, but it was my choice to mount them at the angle of the gable on our roof rather than the optimum angle. Our panels are about 15 degrees angle, when they should be about 35 degrees. Despite reassurances from the salesman, I reckon that the output is reduced by around 10% of what they should put out. The installed capacity did offset our net energy usage.

The initial payment rates for the energy generated was utterly ridiculous - 60 cents per kWh. That was the main reason I went to 3.2 kW, paying the extra for the panels from my own pocket because the rate I received ensured that my system was paid for in just over 3 years. In effect, I had pre-paid my electricity bills and after the break even point, it was all profit. Of course, all good things must end and the best rate I could get was 21 cents per kWh and it is now down to 17 cents per kWh. It will continue to go down as more and more people go solar.

Next, the power companies got smart and introduced charges to cover he distribution of power, so we now get a daily connection charge. About 6 years later, another Solar company happened to come around, offering a 6 kW system for a price less than I paid for my 3.2 kW system. I have a near flat garage roof which could have accommodated the 6 kW array, but about a third of the panels would be in shadow from the main house roof. So I opted to cut back the installed capacity to about 4.6 kW. Now, the salesman for this company was utterly ignorant of the technicalities of the system. In fact, the whole company was shonky in my opinion, but I now have the second array mounted on my garage roof. It is almost horizontal (minimal fall on the roof). Salesman said that these days, the solar panels are not sensitive to sun angles etc. Utter crap! At noon in mid summer, on a cloudless day, I can get about 3.8 kW from the panels. This is from an installed capacity of 4.6 kW. So, setting the panels at the appropriate angle is critical, despite what the salesmen say. I am not complaining because I expected this discrepancy. Our summer production now covers the daily connection fees and energy consumption for the winter period, so effectively we have no electricity bills, despite my wife running the heaters 20 hours per day during winter.

The second salesman tried to sell me the 6 kW system, and I would have taken it if it were not for the shading part of the area where they wanted to mount them. His sales spiel was that we would NEVER have to pay an electricity bill again. If the 6 kW system did generate the full 6 kW, that could possibly be so, but I was suspicious of this guy. My suspicions proved correct when I later tried to get them to answer why the 4.6 kW array was only putting out 3.8 KW maximum and more like 3.6 kW average at peak times. No answer. I tried many times, and no answer was the reply. In short, the second array pus out roughly what I expected it to so I cannot complain.

One thing he did try to sell me (as did a few other salesmen) - they try to get you to hook up your electric hot water to your solar. This is a farce. If you want Solar hot water, put a solar hot water system in. They occupy about 2 sq metres of your roof, which is about the size of one photo-voltaic panel these days. Solar insolation is about 1 kW per sq metre, so 2 sq Metres will be enough to heat your hot water over the period of the day. The solar panels are about 15% efficient, and to get the same amount of energy into your hot water is going to require something like 6 or 7 panels of photo-voltaics. So if a salesman comes to you with teh proposal to install photovoltaics panels to heat your hot water, run the other way as fast as you can...

 

PS - this thread seem to have drifted away from the original post theme of portable power for a caravan, but it is interesting.

-- Edited by erad on Thursday 25th of February 2021 03:39:21 PM

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Unfortunately it is not always possible to get permission for as much solar as you want. I wanted a 5 Kw system got all the quotes and arranged with a supplier to fit it, but when it came to it my electricity supplier ( Origin) said no you can have a maximum of 2.7 Kw. Highly annoyed I rang them and said 2.7 is no good I want 5 Kw. their answer was that will involve upgrading the transformer outside your house we will send you the invoice. I have a 2.7 Kw system. Landy

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 Hi Dave...does Vic gave a Gross feed-in,or nett? If it is nett,your "problem" is easily solved.Cheers

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Yobar I think it is net. Although I was disappointed at not being able to get what I wanted at the time, the solar that I do have saves me a considerable proportion of my power bill each month. Things have changed a fair bit since the solar was installed now though, and if I was going to alter it at all I would be investigating if it would be worth me adding a battery and not selling any power back to the supplier. instead I would be looking at topping up the battery at night with half price electricity of the grid, and or a couple more panels dedicated to just charging the the battery.

erad wrote:

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Yobarr:   I have 2 inverters - one for each array and they are both 5 kVA. There are 2 possible causes for the lower than rated outputs -

1   The panels are made in China (I am fairly certain of that) and 

2   The panels are not mounted near the optimum angle.

 

I am not sure about the power factor of the inverters either - the older one is fairly close to unity. I suspect that it would be about 0.95 or better, because the kWh generated as shown by the inverter is slightly less than that shown by the electricity meter. I haven't been able to check the second inverter because the metering system has been changed and whilst the supply meter can display the energy generated, it is now displaying the total energy produced and I don't know which one is producing what. The inverters do have a total kWh  recording, but I think it doesn't mean much in reality.

 

As for heating the hot water system, as I said above, you need about 6 times the panel area to generate the energy if you are exporting the power back into the grid. Anyway, in my case, we use the power generated during winter and in fact probably for at least 8 months per year to heat our house. We use a reverse cycle air conditioner for that, so it is the most efficient mode of heating other than burning firewood (messy and dirty). I would rather use the energy generated from the solar to heat the house than to heat our hot water any day. As for summer, we have an evaporative air con system which cools the whole house far more effectively that the reverse cycle A/C, which only cools the living areas. So, in summer we generate enough credits to get us through the winter. Now, all we need is to be able to get out of this cold hole for the winter and we will be well in front because the PV system will still be exporting power into the grid, albeit at only 17 cents per kWh these days. I am considering installing a solar hot water system, but the payback period on these systems is about 8 years, and you still need the electric booster during the winter months, so right now, I cannot justify putting such a system on on my roof.

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 Hi Robert...As well as manufacturing the vast majority of panels,China also makes some of the best.Taiwan,South Korea and Singapore also make good panels,but the difference in quality and performance is negligible. Without getting too deeply involved,it is clear to me that you have been ill-advised on several fronts,with roof-pitch being one of them,and inverters another.With North-facing panels,the difference in production between having 15 degrees pitch,and 35 degrees,is only 2%.Your Solar performance  problem is easily solved,but since you seem to have things well under control,I will opt out. However,may I strongly suggest that you find someone who not only knows about Solar,but has your best interests at heart.This clearly has not been the case with the people who sold you the two systems you have.There is much trickery in the Solar industry.Unless you are willing to explore evacuated tubing,forget Solar Hot Water where you live.I wish you well in your endeavours. Cheers

P.S You cannot compare Solar electricity with Solar Hot Water.The first uses SUNLIGHT to generate electricity,while the other uses HEAT to do the job of providing hot water,so they are next to useless in colder areas.

 

 

-- Edited by yobarr on Saturday 27th of February 2021 06:03:32 AM