Author Topic: EEVblog #724 - Home Solar Power System Analysis & Update  (Read 45142 times)

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Offline nowlan

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #125 on: August 03, 2015, 12:05:06 pm »
I think you guys have missed mentioning the STC (solar trading credits) which subsidize the prices here in Australia.
 

Offline mtdoc

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #126 on: August 03, 2015, 12:09:40 pm »
By searcing around it looks like an invertes is somewhere between $2500-$2900 and  $250W panels go for about $260 a piece.

Your PV pricing is way off. Panels can easily be had for half that . Even less for large installers who buy in bulk.
 

Offline HackedFridgeMagnet

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #127 on: August 03, 2015, 02:01:34 pm »
Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess
 

Offline EEVblog

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #128 on: August 03, 2015, 02:05:17 pm »
Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Oooooo  :o
 

Offline DrGeoff

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #129 on: August 03, 2015, 02:28:32 pm »
Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

Was it really supposed to do that?
 

Offline mtdoc

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #130 on: August 03, 2015, 02:37:33 pm »
Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

I believe these new battery systems(like the Sanyo and Tesla) are not really directed at off grid systems.  They are meant to be added on to traditional strict grid tie systems via "AC Coupling" topologies.
 

Offline DrGeoff

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #131 on: August 03, 2015, 02:42:57 pm »
Samsung have a battery pack too, "ESS".
Supposed to be available now. (August)
www.countrysolarnt.com.au/battery-storage/samsung-ess

Now that is tasty.

One issue I see with being completely "off grid" is that, without duplication of the system, a failure could see you powerless for quite a length of time as spares, repairs and replacements have to be sourced and installed. This could be a problem depending on what went wrong and how long it takes to fix.

I believe these new battery systems(like the Sanyo and Tesla) are not really directed at off grid systems.  They are meant to be added on to traditional strict grid tie systems via "AC Coupling" topologies.

Sounds a bit like decoupling capacitors.
Allowing you to recharge during off peak (when power is cheap) and use it during peak times, ie local small reservoir for peak demad periods.


Was it really supposed to do that?
 

Offline LabSpokane

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #132 on: August 03, 2015, 02:46:19 pm »
Sure do. Installers recommend waiting for a few years to see what is left after the dust settles.

Yep.
Unless you are on a remote property or something, I'd wait a few years too.
Every solution seems custom and bodged, Tesla will be the winners in this.
I contacted an Oz company that sells a nice looking German solution that seems similar to the Tesla powerwall, but didn't hear back from them. Meh.

In the near term, Tesla could be making more money of their Powerwall than cars. The killer app is in peak shaving for business and office buildings.  The U.S. Northeast is a hot market for that right now.
 

Offline EEVblog

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #133 on: August 03, 2015, 03:32:40 pm »
Looks like there are a few system available actually, not sure how I missed them before.
The Samsung one, a Bosh one, and Sunnyboy!
http://rfisolar.com.au/browse-products/energy-storage.html
 

Online DimitriP

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #134 on: August 03, 2015, 05:45:42 pm »
Back to solar systems for a moment, :) , I'm having trouble with the $5000AU cost.

In Oz you can get a 5kW system installed for AU$4000 (USD$3k)
http://www.truevaluesolar.com.au/specials/

Not that I didn't believe you, but thanks for the link. Wow!
   If three 100  Ohm resistors are connected in parallel, and in series with a 200 Ohm resistor, how many resistors do you have? 
 

Online DimitriP

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #135 on: August 03, 2015, 06:15:23 pm »
By searcing around it looks like an invertes is somewhere between $2500-$2900 and  $250W panels go for about $260 a piece.

Your PV pricing is way off. Panels can easily be had for half that . Even less for large installers who buy in bulk.
Thaks for the link.
It looks like for the same capacity system the prices in AU are about half as much.
For $3000 US in AU you get a 5KW system up and running.
For $3700 US in the US you get a 3KW system parts that still need to be permitted, installed and inspected. Yeah...there is a small discrepancy there .... :)

I should probably get on the phone with local installers and quit bothering you guys.

It has been an eye opening experience regardfing pricing though. Thanks Dave!!!


   If three 100  Ohm resistors are connected in parallel, and in series with a 200 Ohm resistor, how many resistors do you have? 
 

Offline coppice

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #136 on: August 21, 2015, 04:35:00 pm »
I have a question about mounting solar panels.

I have been looking at some mounting frames for solar panels, and they don't look all that robust to me, especially for an area subject to typhoon/hurricane grade storms. In a severe storm these things are going to be like sails, trying to rip themselves away from their mountings. The mounting frames themselves don't look that tough; the way the panel clamps to them doesn't look that tough; and the way the frame fixes down doesn't look that tough. Are most of these mounting systems proving adequate in practice, or should I be really cautious about this area?
 

Offline mtdoc

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #137 on: August 23, 2015, 06:21:08 am »
I have a question about mounting solar panels.

I have been looking at some mounting frames for solar panels, and they don't look all that robust to me, especially for an area subject to typhoon/hurricane grade storms. In a severe storm these things are going to be like sails, trying to rip themselves away from their mountings. The mounting frames themselves don't look that tough; the way the panel clamps to them doesn't look that tough; and the way the frame fixes down doesn't look that tough. Are most of these mounting systems proving adequate in practice, or should I be really cautious about this area?

Commercial mounting systems (and PV panels) will have specific engineering specifications regarding maximum wind forces, etc which will depend on panel size (surface area) and mounting type (roof versus ground mount).

Geographic locations will have specific data regarding expected maximum wind speeds, etc so that as long as the mounting systems engineering meets the needs for the geographic locale then all is generally fine. Of course with an extraordinary hurricaine or a tornado all bets are off.

Depending on the location - local codes or AHJ may require an engineers stamp certifying structural integrity,etc.
 

Offline apis

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #138 on: August 23, 2015, 09:19:32 am »
Solar is really great, especially if you live closer to the equator. Unfortunately I haven't been able to justify a system here in Scandinavia from an economic perspective at the moment, we don't have that many sun hours either sadly and highest energy demand is during winter when there is even less sun. For a new house, if you go completely off grid, it might make more sense because you pay a lot to install the electric services so that could balance out some of the solar panel installation cost. I live in southern Sweden, that's about 55 degrees north, Sydney is 35 degrees south, that's similar to North Africa, perfect for solar! At least we don't have those huge spiders here. :o
 

Offline mux

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #139 on: November 03, 2015, 10:12:18 pm »
The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif
 

Offline apis

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #140 on: November 05, 2015, 11:31:24 am »
The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif
Is <3yr payback a measured result from an actual installation or a theoretical estimate? This far north the angle of the sun is pretty low during winter as well which I expect would be detrimental, there are many factors so it's hard to be sure what to expect (at least there is hardly any snow these days). But maybe I should look into it again.
 

Offline Delta

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #141 on: November 05, 2015, 12:37:38 pm »
3 year payback? Wow!
What is the cost of a kWh from the grid?
Are you grid tied and on a feed in tarrif?  If so, what do they pay you per kWh?
Was the installation cost subsidised?
 

Offline mux

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #142 on: November 05, 2015, 09:02:01 pm »
The nice thing about Sweden in particular is that you've got a couple of big low-budget solar manufacturers like REC and Aurora that drive the prices down. Sweden has the lowest installation cost after Germany and Denmark.

I get sub-3 year payback times with my system in the Netherlands with only about 10% more sunlight than southern Sweden:

http://www.sapa-solar.com/images/annual-global-irradiation.gif
Is <3yr payback a measured result from an actual installation or a theoretical estimate? This far north the angle of the sun is pretty low during winter as well which I expect would be detrimental, there are many factors so it's hard to be sure what to expect (at least there is hardly any snow these days). But maybe I should look into it again.

It's now had a full summer's production, so I've got enough data to say it does actually stack up. I've got 1970Wp and produced 1220kWh so far over the last 7 months - expected to get just over 1500kWh this year. Next year, a tree that's severely obstructing the panels and casting a shadow around noon every day is going to be gone, so we expect about 1750kWh per year. The installation cost €1090 and our electricity cost is €0.21/kWh, so that's about €315/yr payback. We have net metering here, just like Sweden.

Payback is a lot worse for non net-metering countries; you generally get about €0.07/kWh, which means payback is about 9 years with the same kind of installation.

No subsidies, but I did buy the inverters second hand which saved us ~€200. I also did installation myself. This is a piece of cake nowadays, everything is standardized. There really is no need to have anyone do it for you unless you have a very tall roof or two left hands :P

Solar pays for itself anywhere with net metering now. This won't last of course, so if you're thinking about solar make sure to see for how long net metering is still allowed. Our government was about to abolish net metering starting in 2017, which prompted us to install our solar panels earlier this year. Now they actually extended this to 2020, so we'll definitely have our entire installation paid for in this period, even if something breaks in the meantime.
 

Offline SNGLinks

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #143 on: November 05, 2015, 11:04:05 pm »
In the UK, in order to qualify for the feed-in tariff, the solar power installation has to be done by an approved installer.

I had my system supplied and installed for free and the company who paid for that get the feed-in tariff. I have leased the space above my roof to them.
https://www.flickr.com/photos/snglinks/albums/72157637134670794

Originally my electric meter ran backwards when the sun was shining but the electricity company said that my meter was not compatible with solar power and changed it. :(

I wish now I had a hot water cylinder so I could store some of the energy.
 

Offline Seekonk

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #144 on: November 06, 2015, 01:15:59 am »
Technically grid tie is an ideal solution. Politically grid tie is becoming a dead horse.  Utility payments for solar energy are going to drop and drop.  I divert excess PV solar to hot water.
 

Offline station240

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #145 on: November 06, 2015, 03:07:48 am »
Other problem is most of the existing off grid solutions, are designed as DIY install kits with 12/24/48V batteries, and lower voltage solar arrays.
So using one of them in an existing grid system means rewiring the panels, with thicker cable as well.

I did come across this which takes 48V DC input
http://solar.schneider-electric.com/product/conext-xw-230v-50hz/
And the matching MPPT which converts <600V solar arrays into 48V DC
http://solar.schneider-electric.com/product/conext-mppt-80-600/

It seems to me the small scale off the shelf home storage solutions are either all in one bricks that include everything, or a mains connected battery which is really just a UPS (with obvious double conversion losses). I don't like the all in one solutions, especially as it makes in impossible to keep the expensive batteries somewhere cool, without taking the entire unit inside.

What is really needed is the ability to treat the battery bank as another variable voltage/amps input like the solar array is. Then you can just choose the battery capacity/voltage that suits your needs. Would require a proper standard to work properly.

Companies have made UPSs with modules, for the really huge units anyway. Need more power output, add a second inverter, battery banks are separate cabinets and you can have multiple, same for power input/switching/bypass. Why can't we have a scaled down version that lets you pick and choose what modules you want inside the big white box ?

Given the ongoing development in battery technology, the part most likely to be obsolete is the battery charger and any related BMS (battery management system). Batteries are crazy expensive at the moment, so the builds involving assembled technology (eg mail ordered kits) carry a risk of bricking the batteries, should you over charge/discharge them, let them get too hot, etc. One company recommends people new to offgrid power, buy cheap batteries to start with for this reason.
 

Offline CatalinaWOW

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Re: EEVblog #724 - Home Solar Power System Analysis & Update
« Reply #146 on: November 06, 2015, 03:26:34 am »
Siting is even more important than region in determining solar payback.  I lived in Southern Arizona for years.  A wonderful area for solar.  But my home not so much.  Roof orientation about as bad as possible.  I could have built structures to orient panels better, but making them compliant with neighborhood association requirements would have dramatically added to costs.  Factors which made the house much more livable than many in the area were direct no-nos for solar.  Placement in a small valley limited morning and evening sun, so air conditioning requirements (the dominant electrical load in that region) were greatly reduced, but so was solar potential.  Deciduous trees provided summer shade further enhancing comfort, but hurting solar.

In addition to siting issues, many financial payback calculations make unwarranted assumptions about future costs.  All solar proponents argue that payback periods will be shorter as electricity prices rise.  I have been reading that argument for nearly 20 years now.  Nearly the life of a system installed when I first tried to justify it for myself.  While it does seem likely that it will happen sometime in the future, it is already twenty years later than earlier predictions, and could easily be another few decades away.  Installation of solar being one of the reasons.  You can't add capacity to a market without having a downward effect.
 


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