Solar Power To Power Your Home?

[Crossy]

The reason that an RCD must not be placed between the solar inverter output and the incoming consumers mains is that it could inadvertently disconnect the grid supply from the inverter. (The inverter is permanently wired).

So, since the inverter will shut down on loss of mains, it's purely a convenience issue, not safety?

[electau]

The reason that an RCD must not be placed between the solar inverter output and the incoming consumers mains is that it could inadvertently disconnect the grid supply from the inverter. (The inverter is permanently wired).

So, since the inverter will shut down on loss of mains, it's purely a convenience issue, not safety?

The neutral on the load side of the RCD would have an earth on it through the MEN connection at the main switchboard. The MEN system is mandatory under AS3000 in Australia.

Edited October 5, 2012 by electau

[Crossy]

The reason that an RCD must not be placed between the solar inverter output and the incoming consumers mains is that it could inadvertently disconnect the grid supply from the inverter. (The inverter is permanently wired).

So, since the inverter will shut down on loss of mains, it's purely a convenience issue, not safety?

The neutral on the load side of the RCD would have an earth on it through the MEN connection at the main switchboard. The MEN system is mandatory under AS3000 in Australia.

I think I see where you're coming from, but RCDs are inherently symmetrical so will actually work either way round.

A UK installation would place the inverter on the load end of the device, the inverter output is inherently earth-free so even if it is supplying power to the grid a L-E fault will cause an imbalance at the RCD and open the supply (power will not be disconnected until the island protection trips but it will be disconnected).

We certainly don't get inadvertent disconnections of domestic solar on a regular basis, the IET forums would be full of it if we did.

Anyway, it just goes to show that there is no truly 'right' way to do things, but many and varied safe ways.

[electau]

AS3000. The consumers main neutral connects to the main neutral link. the neutral from the inverter connects to the main neutral link. the MEN bond connects to the earth link and the main earth.

Installing an RCD under those conditions would immediately trip the RCD, (inadvertantly was the incorrect word in the previous post.).

The DC supply from the solar PV array to the inverter is connected through a 2 pole switch for isolation purposes.

The neutral is not switched on an MEN system

RCDs are installed as normal downstream of the main neutral link and MEN bond.

Edited October 5, 2012 by electau

[electau]

This post may explain the connections better.

The connections are as follows.

Consumers main neutral to the main neutral link. The neutral from the inverter to the main neutral link.

The Line conductor from the main switch to the common bus. The Line conductor from the output of the inverter ( through a switch on the MSB ) to the common bus.

Now from this point RCDs may be installed.

With a TT system there is no earth bond at the main neutral link but there is an earth on the incoming neutral upstream on the distribution system.

Both the two DC supply cables from the PV panels to the inverter are above earth potential.

[CWMcMurray]

Hopdafru....

Nakorn Ratchasima Solar has a BOI approved solar power farm project that they are constructing in Isarn, and they are importing all of their solar panels from Europe, so may have some that were damaged in transport

If you are looking for scraps, they may be willing to unload things that have been damaged and that they can not use for this project...

You can always give them a call to check

http://www.spcg.co.th/solarpower/kr1/en/index.php

Edited October 5, 2012 by CWMcMurray

[TwoDogz]

Hopdafru....

Nakorn Ratchasima Solar has a BOI approved solar power farm project that they are constructing in Isarn, and they are importing all of their solar panels from Europe, so may have some that were damaged in transport

If you are looking for scraps, they may be willing to unload things that have been damaged and that they can not use for this project...

You can always give them a call to check

http://www.spcg.co.t...r1/en/index.php

Geez, the Thai made ones from Solartron must be good then.

[sezze]

It is cheaper these days , and grid connecting is possible now . This will save you a lot on the batteries so payback time is now actually quite within reach .

Bullsheister.

While it can be done, it is not being done. This from the biggest listed solar company here that visited my place the other week for a quote....800k.

hahaha , go visit other companies . I can give you some links ( thai links ) if you want , and even from a westerner who've just done it . 3kWp installed , together with on-grid inverter ( no batteries needed ) , for ... less then 150k . Output between 12 and 15 kw daily makes the payback time around 7 years . You can even go cheaper if you import some stuff and then payback time drops to less then 6 years .

[Crossy]

Yeah, that figure of 6-7 years payback on a grid-tie system ties up (sorry) with my own calculations, worth doing (just).

[sezze]

Yeah, that figure of 6-7 years payback on a grid-tie system ties up (sorry) with my own calculations, worth doing (just).

That depends , elec will be more expensive in the years to come . The initial price you paid for the solar stays the same . So the projected time is on the elec price now . In 10 years , i guess the elec went up quite a bit ...

[electau]

The reason that an RCD must not be placed between the solar inverter output and the incoming consumers mains is that it could inadvertently disconnect the grid supply from the inverter. (The inverter is permanently wired).

So, since the inverter will shut down on loss of mains, it's purely a convenience issue, not safety?

The neutral on the load side of the RCD would have an earth on it through the MEN connection at the main switchboard. The MEN system is mandatory under AS3000 in Australia.

I think I see where you're coming from, but RCDs are inherently symmetrical so will actually work either way round.

A UK installation would place the inverter on the load end of the device, the inverter output is inherently earth-free so even if it is supplying power to the grid a L-E fault will cause an imbalance at the RCD and open the supply (power will not be disconnected until the island protection trips but it will be disconnected).

We certainly don't get inadvertent disconnections of domestic solar on a regular basis, the IET forums would be full of it if we did.

Anyway, it just goes to show that there is no truly 'right' way to do things, but many and varied safe ways.

Yes Crossy , you propose to install an RCD to protect the Inverter. I can see your point if the installation is TT. The load side of the RCD is connected to the inverter output terminals. the load side of an RCD is where the test button obtains supply.

With an MEN system the earth fault loop impedance will be low enough to operate a protective device within 0.4secs. The inverter has an earth teminal fitted and must be earthed.

The inverter is a permanently connected device and if the installation is MEN an RCBO is not required to be installed. A plug and socket can not be used as a means of disconnection for the inverter.

TT system install RCD. MEN system RCD not required. The inverter would normally be protected by a 20A MCB at the switchboard. With a TT system this would be a 20A/30mA 2 pole RCBO.

The inverter is normally installed near or adjacent to the main switchboard.

There is another matter concerning GCIs an that is the stability of the grid supply. It should not be less than 200VAC and frequency variation of +/- 1Hz at 50Hz.. Outside these parameters the GCI may not synchronise with the grid or drop off the grid.

[sirineou]

Yeah, that figure of 6-7 years payback on a grid-tie system ties up (sorry) with my own calculations, worth doing (just).

That depends , elec will be more expensive in the years to come . The initial price you paid for the solar stays the same . So the projected time is on the elec price now . In 10 years , i guess the elec went up quite a bit ...

Projections of system payback change downward as electric utility prices rise.

Important number to remember is, if doubling number..

I will not explain the math here, but , if something increases at a 7% rate, it will double in 10 years,

so of your electric bill goes up even by a rate of 3.5% per year, in 20 years ( the projected life of a PV system) you will be paying double of what you are paying now in electric.

. .

Edited October 6, 2012 by sirineou

[electau]

If you do a google search entitled. PEA/MEA grid tied solar systems in Thailand. There is some information on the proposed "smart grid"

[Crossy]

If you do a google search entitled. PEA/MEA grid tied solar systems in Thailand. There is some information on the proposed "smart grid"

Nice to see that the top two hits are Thaivisa threads including this one

[electau]

If you do a google search entitled. PEA/MEA grid tied solar systems in Thailand. There is some information on the proposed "smart grid"

Nice to see that the top two hits are Thaivisa threads including this one

See this link, mentions residential PV installations.

http://www.docstoc.com/docs/114942727/12-3-Thailand-3_Photovoltaics_

[electau]

Based on a residential rate of 4B per kWh, if one uses the gross method of calculation if you have a 2.15 kW PV array and when harvesting generate an average of 8.4kWhs per day and you consume 20kWh per day from the grid you would save 11.6kWh per day, ie. 11.6 x 4 = 46.4B.

Per month that would equate to 1392B. per year 16704B.

To calculate the approximate pay back time in years you would require the full cost of the solar installation including installation plus allowance for maintainance per year over a period of say 10years.

The value of the equipment depreciates in value every year and these calculations have not taken into account price rises in retail electricity in the future.

[sezze]

Based on a residential rate of 4B per kWh, if one uses the gross method of calculation if you have a 2.15 kW PV array and when harvesting generate an average of 8.4kWhs per day and you consume 20kWh per day from the grid you would save 11.6kWh per day, ie. 11.6 x 4 = 46.4B.

Per month that would equate to 1392B. per year 16704B.

To calculate the approximate pay back time in years you would require the full cost of the solar installation including installation plus allowance for maintainance per year over a period of say 10years.

The value of the equipment depreciates in value every year and these calculations have not taken into account price rises in retail electricity in the future.

I do agree on your calculations , with some minor additions . Like the elec rate now i'm paying 3.85baht/kwh ( close to your 4 ) . The most important thing i wanted to say is . The maintenance and value of the install . Maintenance of a solar system is nothing at all . If you want the max out , then you should clean it once a while , a water spray will do . That is the only maintenance needed . 2nd is the value , the degenrative value is the grid tie inverter which can break down . There are many kinds of inverters , but any decent one will now have a lifetime of at least 10 years . Some have warranties for much longer then that . The technology and mtbf of these inverters has been improved a lot the last 5 years . In a calculation you need to count at a 10 year lifecycle of the inverter . The solar panels itself can very very occasionally break down . Normally they last about your lifetime and probably longer . The output power on 99% of the panels is warranted of 85% of output power after 25 years and in general they succeed with big margins . Sure you will see them changed but most times it is not because they are broken but because the output of new panels is higher then on the old ones . If you do have the room they are kept in place . Others who do not have the room for additional panels order more efficient ones so will get higher kWp/m2 .

[ABarbarian]

Just a quick note about calculating cost on a Hybrid or off-grid system like myself batteries will be a large consideration. Using information obtained from ABO's experience, I have been quoted:

1) YUASA Deep Cycle batteries @6000B, require regular maintenance and lifespan of about 5-7 years.

2) RITAR Deep Cycle "Free Maintenance" batteries @13500B, no maintenance and lifespan about 10-15years

3) also top of the line gel batteries which I have not been quoted on

- important with batteries is if they discharge often or the control of the charge into them is not managed well, ie with a cheaper Charge Controller, their lifetime reduces.

- I am building about a 5KW system and need 8 batteries, in fact should have a third set of 4 making 12 batteries, but am starting on the small side. 8 batteries Yuasa = ~50,000B, Ritar = ~110,000B

- If planning at realizing costs in about 10-20 years you will be replacing the batteries 2-3 times, adding 50-150k to your system cost over that time.

[electau]

Here is a typical warranty for an inverter. 5 years for a manufacturer (fully comprehensive) includes product, installation and labour with an optional 5 years optional manufacturer warranty available to purchase before installation ( extra cost applies). includes installation and testing.

Panel warranty, 15 years full replacement with a fully comprehensive period of 10 years. Performance guaranteed for 25years, 80% output based on 15% to 17% efficiency.

Installation. Defects liability period 12 months.by installer.

Yes, maintainance costs are minimal but should be allowed for eg. 4 hours a year.

[MauroHKT]

I noticed that every one tend to consider maintenance costs, performance etc. but no one has ever seen in the various counts on ROI that the price of the current is not stable and tend to increase more than 5% per year.

I think this makes ROI much shorter.....

[balderdash]

When using batteries for a true off-grid system, that is the batteries are cycled every day, then deep cycle batteries are needed. But, in a hybrid situation, where you are grid-tied 99.9% of the time, they don't make sense. My little hybrid system is using 12V second-hand car batteries, because they are almost never cycled. With a battery maintainer or desulphator they will last a long time, ready for that day when the power goes out for a few days... of course if it is a long term power outage (weeks or more) you are out of luck as the auto batteries will probably die out.

If I were to use deep cycle batteries for a hybrid system, I would try to make use of them as they are designed, to deep cycle thousands of times (or at least hundreds of times) Thus, I'd at least think about buying, or building, an EV vehicle. Maybe an electric tuk-tuk or electric motorbike (seen one running around town the other day), that you could use daily and also would serve as a battery array during a long term power outage. An EV MB would not provide much back up power though.

Any thoughts on this idea? I just can't see using extremely expensive deep-cycle batteries in a hybrid system.

[jbrain]

When using batteries for a true off-grid system, that is the batteries are cycled every day, then deep cycle batteries are needed. But, in a hybrid situation, where you are grid-tied 99.9% of the time, they don't make sense. My little hybrid system is using 12V second-hand car batteries, because they are almost never cycled. With a battery maintainer or desulphator they will last a long time, ready for that day when the power goes out for a few days... of course if it is a long term power outage (weeks or more) you are out of luck as the auto batteries will probably die out.

If I were to use deep cycle batteries for a hybrid system, I would try to make use of them as they are designed, to deep cycle thousands of times (or at least hundreds of times) Thus, I'd at least think about buying, or building, an EV vehicle. Maybe an electric tuk-tuk or electric motorbike (seen one running around town the other day), that you could use daily and also would serve as a battery array during a long term power outage. An EV MB would not provide much back up power though.

Any thoughts on this idea? I just can't see using extremely expensive deep-cycle batteries in a hybrid system.

With a battery maintainer or desulphator they will last a long time, ready for that day when the power goes out for a few days..

I guess you must have a whole srap yard of used car batteries hooked up as you will last a few days without power

[balderdash]

No I don't. But, at 1/10th the price, per Ah, of new deep cycle batteries I "would" extend the system to a big enough size. You only need to store power for the non-daylight hours usage,

using solar charge controllers. I assume I'd cut back power usage during a long term outage as well. My "little" system is just in the experimental stage, but easily extendable.

The point of my post was to put forth the question of whether or not deep cycle batteries were needed for a hybrid system. I don't really think so, as the quality of the grid should increase

in Thailand over the coming years... one hopes.

"a whole srap yard of used car batteries" do you have some sort of calculation showing one needs N times more space if using second hand auto batteries versus deep-cycle? Or indeed, just auto batteries versus deep cycle. Do you know the working capacity of those used car batteries versus their design capacity? Just curious.

[jbrain]

No I don't. But, at 1/10th the price, per Ah, of new deep cycle batteries I "would" extend the system to a big enough size. You only need to store power for the non-daylight hours usage,

using solar charge controllers. I assume I'd cut back power usage during a long term outage as well. My "little" system is just in the experimental stage, but easily extendable.

The point of my post was to put forth the question of whether or not deep cycle batteries were needed for a hybrid system. I don't really think so, as the quality of the grid should increase

in Thailand over the coming years... one hopes.

"a whole srap yard of used car batteries" do you have some sort of calculation showing one needs N times more space if using second hand auto batteries versus deep-cycle? Or indeed, just auto batteries versus deep cycle. Do you know the working capacity of those used car batteries versus their design capacity? Just curious.

Below are a few interesting reads for you

http://www.batteryweb.com/pdf/inverter_battery_sizing_faq.pdf

http://www.batterystuff.com/kb/articles/battery-articles/battery-basics.html

http://www.solar-electric.com/inverter-basics-selection.html

http://www.solar-electric.com/deep-cycle-battery-faq.html#Lifespan%20of%20Batteries

http://www.batterystuff.com/kb/tools/peukert-s-law-a-nerds-attempt-to-explain-battery-capacity.html

Edited August 5, 2013 by jbrain

[balderdash]

Thanks, looks like good info.

As I see it now, I use about 20kwh/day. I think, in a power outage situation, I could cut that down to 16kwh easily. I looked at what

the usage would be in the dark hours (after the solar power would not be available) and that would be about 6kwh. After depth of

discharge, battery efficiency, wire losses, and inverter efficiency considerations, I'd have to bump that up to almost 19kwhs of battery

capacity. That comes out to about 12 of the auto/truck batteries I would buy. Second hand, half decent batteries, for $25 a pop. Just

one of the 3K deep discharge 140Ah? batteries I think I saw at Amorn was almost $200. So, for backup, as I implied, I am too cheap

to buy quality. 12 batts for $300 versus comparable new deep cycle capacity for about $2400. 12 batteries, not exactly a scrapyard

size, but a fair footprint I suppose.

I'll try to read over your links and see if my calcs are off by much. Anyway, I'm looking for a cheap, backup system for what would be

primarily a grid-tie system. If after the first 3-4 day brown-out my junk batteries are all dead, que sera sera. I'll buy more, and wait another

(hopefully) few years before another long outage.

[Naam]

I noticed that every one tend to consider maintenance costs, performance etc. but no one has ever seen in the various counts on ROI that the price of the current is not stable and tend to increase more than 5% per year.

I think this makes ROI much shorter.....

the price of electricity increased in 8 years by ~16%, that's a linear increase of 2% p.a. nearly all of that increase happened during the last 15 months.

[balderdash]

Of course inverter and panel prices are dropping, not just in real terms, but in nominal terms. So, if one needs to replace a component in five or ten years, it should be (all

things being equal) much less of a hit on your wallet. Racking and wiring costs have gone from a very small part of the equation, to a much bigger piece. Soon, or maybe even

now, trackers just don't make sense either.

For me, I'm thinking of building up a system maybe 1KW at a time. Averaging down in price, hopefully, over the next 2-3 years.

[jbrain]

Of course inverter and panel prices are dropping, not just in real terms, but in nominal terms. So, if one needs to replace a component in five or ten years, it should be (all

things being equal) much less of a hit on your wallet. Racking and wiring costs have gone from a very small part of the equation, to a much bigger piece. Soon, or maybe even

now, trackers just don't make sense either.

For me, I'm thinking of building up a system maybe 1KW at a time. Averaging down in price, hopefully, over the next 2-3 years.

Keep in mind that the Chinese panels are currently priced below manufacturing cost. The panel makers are heavily subsidized by the Chinese government, and the major producers are still in foreclosure.

[balderdash]

Yes, true. Also, the tariffs in Europe and America seem to be coming off already (at least in Europe), which might cause panels that would botherwise e dumped here, to start heading that way again. Who knows.

[Canada]

Does anyone know about the viability of a solar system specifically built to sell power to the grid?

I have several large systems in my area and am told that that is what they are.

Sugarcane isn't paying that great....

Actually, I just googled it. There are many solar farms here. Large projects by large groups with large money. What about the viability of doing this on a smaller scale?

Anyone have any "quick" information??

Edited August 6, 2013 by Canada