Author Topic: Photo Voltaic panels.  (Read 4622 times)

Offline DavidA

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Photo Voltaic panels.
« on: December 23, 2015, 12:49:23 PM »
Has anyone here fitter PV panels to their house ?

I'm thinking more of the Grid Tie system, not the battery storage one.

If so, could you give a quick run down of what it actually cost to get them installed, the complete installation, and what is the power output on an average day.

I have to make some assumptions and am guessing that they will only provide power for around ten hour a day on average.

Also, is it correct that you are only allowed to have 4 Kw fixed to a domestic residence ?

Dave.

Offline CrazyModder

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Re: Photo Voltaic panels.
« Reply #1 on: December 23, 2015, 02:06:49 PM »
In the cases I witnessed (friends etc.), people with average sized PVs (whatever that means) basically created more enough electricity during summer days to drive their home with all applications on full steam. Their problem was that they were simply unable to use the juice. Sure you get money by injecting it into the Grid (at least where I live, it's heavily subsidised), but ecologically some form of energy storage would be best.

Of course, you get nothing in the night (duh) and only mediocre when it's overcast. But to be more specific, you'd have to tell us more about your case - size, orientation of your house, average number of brigt days, etc.

By the way, people also were quite happy about solar warm wasser panels, just to keep it interesting... One guy here keeps a dedicated panel on ground level to heat his swimming pool, works like a charm.

Offline PK

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Re: Photo Voltaic panels.
« Reply #2 on: December 23, 2015, 06:07:49 PM »
We have 5KW PV systems on the roof at home and at work.
PV installation is such a competitive market that you really need to be careful of companies trying to pull the wool over your eyes to shave a few bucks of their costs.

The easiest scam to spot is the "only $1500 for a 5KW system" line. Read the fine print and you get a 5KW inverter and 4 x 250W panels. Similarly, avoid any deal with the word 'up-gradable' in it's tag line.

The next problem is a bit nastier.  A few years ago, everyone's solar panels generated 180W each, then they were generating 200W each, now everyone is selling 250W panels... Whilst PV efficiencies have improved over the years, they haven't improved by 39%!  A modern panel will produce 250W of electricity if a small star explodes immediately above it, and about 200W on every other day. Seriously though, we live in Perth Australia which has about the best weather you can get for PV solar. We see 5KW out of our systems for about 10 minutes, 3 days a year. Fortunately, there's a good fix for this, but I'll come to that in a moment.

The next problem is that the earth is irritatingly spherical. If you live at a latitude > 30 deg, then you are going to want to install the panels on an angle. If you are lucky, then you have enough angled roof space pointing in the right direction. If not, then you probably need to buy angled mounting frames, these aren't expensive, but they also aren't listed in the advertised price either. There is an alternative though, we have a flat roof at work and we didn't buy angled frames, I'll get to the magic fix soon.

The last thing to consider, is that panel outputs drop over their lifetime. You'll be down to 80% capacity after 6 years or so.

So... the magic fix....  Buy 10% more panels than your inverter will deal with. On a 5KW system, buy 22 panels instead of 20. At 32deg lat, it works out the same price as the tilting frames and delivers the same result. Alternately, you will get closer to the maximum power of the system on more days.  I guess if you live further north or south, then you could add even more panels. It means you'll get more power for longer as the system ages, all of he installers we spoke to were happy to do this...

Oh, and price?  In Australia, you pay around AU$1 per Watt of installed capacity at the moment. (might have come down in the year since we did ours)

These are just my experiences, I'm sure others will have theirs...

Offline JHovel

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Re: Photo Voltaic panels.
« Reply #3 on: December 25, 2015, 05:01:18 AM »
I'm also in Australia - so my information is for only general purpose for you (in Great Britain).
I have 3kW and it covers our use (2 adult household, but with borewater for toilet and garden (1.5kW pump) and tankwater (0.75kW pump) for drinking, whashing, showering etc.). And we have aircon running every other day in summer during sunshine hours.
We have a credit on our bill in Summer and run it down to near zero in Winter. We haven't paid for electriity for years.

As far as fitting more panels than the inverter capacity: caution in cold climates! If your temperature goes below zero (Celsius), then your panels may produce MORE than their rating on a bright sunny day, if the panels are optimised for winter angle rather than average insolation angle. There have been problems as a result! In most of Australia, the panel temperature gets too high to ever do that and we can take liberties with installing more panels....
The comment about 180W versus 250W (and now even 300W) panels is that they are different physical sizes: the newer panels are a bigger area - as well as slightly more efficient. I think that was a red hering - although DO BE careful comparing quotes as indicated!

A really good development here is the installation of 'community' solar systems: a few streets or a whole suburb agree to install PV panels on ALL properties and the feed in to the grid is managed at the substation, rather than at the individual property. That way, the generated power is shared among all residents, before it is fed into the grid. The coist of the power imported into the community is also measured and costed at the substation - and the cost shared according to use from each property. That balances the demand and supply for the electricity supplier (who can make some savings in infrastructure) and it makes larger industrial level STORAGE systems viable. Everyone wins!
Worth looking into as a social action project.
Cheers,
Joe

Offline jcs0001

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Re: Photo Voltaic panels.
« Reply #4 on: December 25, 2015, 01:49:32 PM »
We are located in southern British columbia (Canada) where the summer's are sunny but the winters often quite overcast.  Had approx. 3200 watts of panels installed about 3 years ago.  They are grid tied and produce around 3300 kwH per year.  That is somewhere around 1/2 of our use.  The cost including all materials and installation was approx. $12,500 Can. Our roof is about 20 deg. off due south facing and is fairly low slope.

Our house is all electric including a mini split heat pump that we use in moderate weather in the winter.  In cold weather (-10C or lower) we usually use our wood insert fireplace - it is fairly efficient.  We rarely use air conditioning in the summer.  We would be classed as very frugal with energy compared to most residences in Canada - I have done a lot of insulation, very good windows - the last 5 recently installed are triple pane etc.  Our use in a typical year is around 6500 kwH.

The house is an older one, not well designed and too big.  Our building codes over the years have allowed for quite shoddy practices and are still not written with energy efficiency in mind.  I suspect a lot of people in other countries would be horrified at 6500 kwH per year for two people and one cat.

In our area we are allowed to install (grid tie) only enough panels to cover our use throughout a typical year.  The utilities don't want us to install more than that although I'm not sure how strict they would be in that regard.  We put on as much wattage as the roof would allow - we also have a domestic hot water system on the roof so that limited the space available.

John.

Offline russ57

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Re: Photo Voltaic panels.
« Reply #5 on: December 26, 2015, 05:09:11 AM »
I'm in Melbourne,  Australia.  I have 4.5 kW installed,  flat,  as Pk proposed above. My install is slightly unusual,  in that each panel has its own micro inverter rather than a single large unit.  I took this approach as I have some unavoidable shading,  on a string install shading of one panel can reduce output quite considerably.  The installation was dearer than the lowest tv advertiser,  but they had actually refused to install a standard system a couple of years ago because     - their -  chosen location was too shady.  (although cheap to install to)
The panels are now located on a  much better position . Yesterday,  a clear sunny (and hot)  day I generated 25kwh,  today 18kwh although it rained most of the morning.
I'm about to install battery storage,  primarily because we have had 5 outages in the past month,  not for economic reasons.

Offline PK

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Re: Photo Voltaic panels.
« Reply #6 on: December 26, 2015, 05:21:42 AM »
I reckon Micro inverters make a lot of sense, they significantly decrease a lot of the losses you get in a single inverter setup and give you more flexibility. We couldn't make a case for them in our setup, but they're probably cheaper now..

Offline RodW

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Re: Photo Voltaic panels.
« Reply #7 on: December 28, 2015, 06:05:36 AM »
I've got 7kW of panels feeding a 5 kW Sunnyboy inverter in Australia. The installer said that Sunnyboy would warrant the inverter at 7 KW input. I sent data to www.pvoutput.org for quite a while. Here is a graph of a really sunny day in October that produced 38 kW.



You can see that the daily output follows pretty much a "normal curve". (Google it if you are not a statistician). On this day, the maximum output was at the limit the inverter could handle. On really hot days, the inverter clips the output at 5 kW so you end up with a flat top on the middle of the curve.

You can see there is a bit of shade in the early morning that distorts the curve which is back on track by about 6:30. There was also a bit of cloud at about 2:30.

In my experience, a house has an idle  power consumption that is consumed all the time . In my case, it is about 1KW. If you monitor consumption,  you see this idle current consumed 24/7 with occasional peaks when you turn on a kettle or oven etc. Managing this idle current will have the biggest impact on electricity cost.

Anyway, I don't monitor the solar system anymore but hope this helps to visualise what actually goes on.

Oh and this madmodder used a Raspberry Pi to capture the data via a Bluetooth dongle from the inverter and for quite a while used a TV dongle on the Pi to capture power consumption (using some custom code) from an Effergy wireless power monitor and send both consumption and generation data to pvoutput.
RodW
Brisbane, Australia

Offline DavidA

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Re: Photo Voltaic panels.
« Reply #8 on: December 28, 2015, 02:10:40 PM »
Crazymodder,

As you are in Germany it seems as if your installation is more relevant to my inquiry than the reports from folks in Australia; though Canada is similar.

At the moment I'm only gathering data. My house faces south and a pretty much unshaded aspect is available for most of the daylight hours.  I am interested in the grid tie from the point of view that when the sun is shining most (in summer) you don't need the power so much. So why not sell it back to the grid.

My main concern with any kind of Sun power is that we have had a lot of cloudy days over the last few months.

I may set up an experimental panel (maybe two, one a Sun tracker) and see what results I get before committing to buying more.

Does anyone here in the UK have them fitted ?

Dave.

Offline chipenter

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Re: Photo Voltaic panels.
« Reply #9 on: December 28, 2015, 02:59:50 PM »
I have a 24volt lathe and use two 12volt 8 watt solar pannels , the lathe motor is 32 watts and have only had to use the mains charger twice this year , eary March and last week even on a dull day they will put some charge into the two 70 amp houre batterys , before I fitted the pannels I was charging the batterys every two to tree weeks .
Jeff

Offline appletree

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Re: Photo Voltaic panels.
« Reply #10 on: December 28, 2015, 03:37:12 PM »
I recently had 3.4kw panels fitted (3 months ago) grid tie and wired in series, The most o/p I have seen is about 2kw.
The thing is the sun is very low in the sky at this time of year, my roof faces due south, even so cloud can soon upset things, I also have a tall silver birch tree which casts a shadow.
I am quite confident that once the sun is higher things will be fine.
It would seem that panels tracking left to right would give an improved o/p however the panels would need to be spaced such that adjacent panels did not cast a shadow on each other.
If the above was your wish there is a planning issue regarding the hight above the existing roof.
To be honest if you are south facing, donít over complicate the job, pay the man before the feed in tariff disappears altogether.
Not been arrogant but like so many thing there needs to be a degree of faith.