Solar Powered Home In Thailand

[manarak]

Thank you Naam

this all makes perfect sense :-)

There are some misunderstandings in what I want to achieve with the calculations.

basically you have to abandon the idea using photovoltaic energy without battery buffer. you can do that with a waterfall or a poolpump but not with gadgets which need a constant supply such as fridge/freezers, routers and computers, water supply of the house, etc.

I never had the intention to run a PV system without batteries.

My goal was to establish a formula to determine the output from the panels, so that the formula can later be inverted to determine panel surface based on energy needs.

Getting such formula is my step 1 of analysis.

don't hold it against me but i refuse to check and comment on [at present time] a futile undertaking

I'd like to confirm at this point that my goal here is not designing a particular system, but establish a system of equations which would allow planning such a system and to calculate costs & return.

I don't expect the architecture of a PV system to change much in future, I guess in 10 years we'll still have panels, inverters, batteries or some kind of E storage + charge controller.

So, if I put together the equations today, I'll be able in future to just fill in the new performance and price data of new equipment to quickly compute ROI.

Currently I have the problem that I got two ways to calculate the panel output, and the methods produce different results.

hmm...

where is the mistake?

Another topic I would like to know more about is the "load balancing".

i.e. Which piece of equipment is responsible for balancing between PV and grid power?

I guess a given circuit cannot be powered at the same time by PV and grid power, so the circuits need somehow to be automatically switched to another power source depending on the available PV power?

What does this mean for the appliances running on the circuits? Will a computer without surge protector switch off when its circuit gets switched or is the process a smooth one?

[manarak]

rated efficiency of the Kaneka panel seems to be wrong.

the panel was tested in California and rated 57W @ 1000W insolation. at 20°C.

the panel's size is 0.9813 square meters, so the efficiency would be 57 * 1/0.9813 / 1000 = 5.8085 % and not 6.3% as rated.

so, new attempt at a bottom-up calculation:

starting efficiency of the panel: 5.8085 %

efficiency loss because of temperature: let's assume the panel will operate at 50°C in Thailand, that's 30°C difference, and the panel is said to loose 0.26% per °C.

Assuming the loss is constant between two °C, the total result is probably meant to be geometric:

i.e. the loss is 1.0026^30 - 1 = 8.1%

temperature-corrected efficiency is 5.34 %

the figure of 5.34% would be valid if a tracker always put the panel in the correct position.

Wikipedia says that trackers improve solar panel performance by 36%.

So I deduct that not using trackers will negatively impact our panel efficiency by the same ?

(does anyone have panel performance stats for Thailand, especially tracker vs. non-tracker installations?)

i.e. efficiency becomes 5.34 * 0.64 = 3.416 %

So, if we wanted to produce 100 KWh with these panels in the season with less insolation, i.e. 4.55 kWh/day/m2, we would need:

100/4.55/0.03416 = 643.38 square meters of installed Kaneka panels,

or 655.65 panels which is more or less equal to gregb's estimation - Hooray, it works!

But... 650 square meters of panels is huuuge :-/

[Naam]

I never had the intention to run a PV system without batteries.

Another topic I would like to know more about is the "load balancing". i.e. Which piece of equipment is responsible for balancing between PV and grid power?

I guess a given circuit cannot be powered at the same time by PV and grid power, so the circuits need somehow to be automatically switched to another power source depending on the available PV power?

What does this mean for the appliances running on the circuits? Will a computer without surge protector switch off when its circuit gets switched or is the process a smooth one?

in my case the answer is rather easy because i run some electronic items (computers and TVs) from batteries via inverter. the switch from batteries to grid and vice versa is done by the individual inverter, quite obviously in milliseconds because neither my computers nor my screens blink an eye. however (very) few appliances need even shorter switching times, e.g. one of my modem/routers and the harddrive recorder in my TV-room. on the other hand, the harddrive recorder (different brand) in my wife's study has no problems when power is switched from one source to another one.

my inverters (imported from India) seem to an excellent job in this respect.

but now we have reached an area where my knowledge is limited. it would be advisable to ask the resident experts Crossy and ElKangorito to chip in.

[manarak]

Naam, how much kWh do your panels produce and how much is your monthly utility bill (averages)?

[Naam]

Naam, how much kWh do your panels produce and how much is your monthly utility bill (averages)?

i thibk i mentioned already that i don't use solar Manarak. my three sets of battery powered and grid charged inverters kick in when one or more phases are low or completely missing. the inverters power the watersupply pumps to our house, the study of my wife (computer, music and TV), my study (tree computers) and my TV-room.

quote: "150kWh/d seems too high. my fully airconditioned house has more than 600m² living area (a total of 19 aircon units) average temperature 26.5ºC, 4 persons (wife, myself and two live-in domestic employees). besides aircons main consumption by 2 huge fridges 1.9kW, 2 average size fridges 0.8kW, pool pump 1.5kW, deep well 1kW, pressured water supply to the house 1.6kW, irrigation pump 1.5kW, pond/waterfall 2 x 1 kW, cooking by electric each and every day as we prefer to eat at home instead of frequenting restaurants.

average consumption (based on 3½ years experience) 94kWh/d (@ 3.8 Baht per kWh). worthwhile to mention: my consumption does not vary too much as i use a big aircon unit to heat my pool in the "cool" season. there is only a small variation hot/cool season. in the hot season my aircons are ~55-60% and in the cool season ~45-50% of the total consumption."

http://www.thaivisa.com/forum/Solar-Powere...96#entry3374996

electricity bill varies between 10-12k Baht, average 11,000 Baht/month.

[manarak]

yes, you mentioned that, I am sorry!!

I must be losing brain power already

[Naam]

yes, you mentioned that, I am sorry!! I must be losing brain power already

none of us is getting younger

[HannahD]

Can someone give a simple definition of "well insulated house" in Thailand. All I have ever seen are concrete post and beam structures with concrete-stuccoed brick infill. What is used to insulate and where is it applied?

[lannarebirth]

I bought the book about this house. Not just solar but a whole lifestyle change.

http://www.architectureweek.com/2003/0514/...onment_1-2.html

http://www.inhabitat.com/2006/10/07/bangkok-bio-solar-house/

That was about 5-6 years ago so maybe there's some new stuff going on.

[Naam]

Can someone give a simple definition of "well insulated house" in Thailand. All I have ever seen are concrete post and beam structures with concrete-stuccoed brick infill. What is used to insulate and where is it applied?

it starts by using gasconcrete blocks which are "glued" (2mm special mortar) together and double outside walls with either additional insulation or just an airgap of 8-10cm (closed on top). ceilings should be insulated with mats which are on both sides backed by aluminium foil. additional measures to save energy are a well ventilated attic (preferrable forced ventilation by an electric exhaust fan), heat reflecting glass and glazed roof tiles. there's a list of additional "dos and don't" which are important but do not fall under the category of insulation. in my case the estimated energy savings are between 5,000 and 5,500 Baht/month.

[Naam]

I bought the book about this house. Not just solar but a whole lifestyle change.

http://www.architectureweek.com/2003/0514/...onment_1-2.html

"The air conditioning unit has a capacity of 9000 Btu and can operate around the clock. At peak capacity it consumes 6.45 kilowatts."

that's not lifestyle but pure refined technical rubbish!

[eddiench]

Hi there...

I'm a newbie in Bangkok. Just lived here over 6 months now. I'm planning to buy a house in Bangkok. I know it's gonna be Songkran (hottest day of the year) and the weather all year round in Bangkok is generally hot. I've seen couple of single houses which I'm interested in but when I entered the house, it was extremely hot (even with 1 A/C turned on). I know I'm gonna spend a huge amount on electric bills to cool down the house during the day and also night time.

Therefore, I've read all of your comments above and found it very interesting. Please forgive me as I've zero knowledge in solar energy and seriously, all the above sounds alien to me. I've heard many comments from people around saying solar energy is expensive to install and does not justify the cost of paying for grid electric. Is this true? Also...I've searched google and could hardly find any interesting installer in Bangkok. If you have any recommendations, it would be so kind of you to share the info.

Insulation. Sounds a whole lot to me. As though the entire house needs to be thorn down for the matter. Then again, it sounds really logically to do it as the heat in Bangkok is burning. In that case, if I'm going to insulate my new house...do I need to re-do the walls around, the ceilings and roofs? A friend of mine told me that tinting the many window glasses in this house would be a bad idea. Somewhat creates a green house effect...I've no idea. Anyone knows bout this? Also, any recommendations on the installers in Bangkok?

Thanks in advance.

Btw...the passed few months was terrible. It was already extreme hot during the day and by night, I had to buy ice blocks to dump it into the water tank so that my family and I can take cool showers. I know it sounds crazy but it's better than taking hot showers on a hot day.

[JimShortz]

Hi there...

I'm a newbie in Bangkok. Just lived here over 6 months now. I'm planning to buy a house in Bangkok. I know it's gonna be Songkran (hottest day of the year) and the weather all year round in Bangkok is generally hot. I've seen couple of single houses which I'm interested in but when I entered the house, it was extremely hot (even with 1 A/C turned on). I know I'm gonna spend a huge amount on electric bills to cool down the house during the day and also night time.

Therefore, I've read all of your comments above and found it very interesting. Please forgive me as I've zero knowledge in solar energy and seriously, all the above sounds alien to me. I've heard many comments from people around saying solar energy is expensive to install and does not justify the cost of paying for grid electric. Is this true? Also...I've searched google and could hardly find any interesting installer in Bangkok. If you have any recommendations, it would be so kind of you to share the info.

Insulation. Sounds a whole lot to me. As though the entire house needs to be thorn down for the matter. Then again, it sounds really logically to do it as the heat in Bangkok is burning. In that case, if I'm going to insulate my new house...do I need to re-do the walls around, the ceilings and roofs? A friend of mine told me that tinting the many window glasses in this house would be a bad idea. Somewhat creates a green house effect...I've no idea. Anyone knows bout this? Also, any recommendations on the installers in Bangkok?

Thanks in advance.

Btw...the passed few months was terrible. It was already extreme hot during the day and by night, I had to buy ice blocks to dump it into the water tank so that my family and I can take cool showers. I know it sounds crazy but it's better than taking hot showers on a hot day.

Are you sure that Thailand is the right choice for you? Do you really want to invest in a property on a place where you find the climate unbearable?

[eddiench]

Hi there...

I'm a newbie in Bangkok. Just lived here over 6 months now. I'm planning to buy a house in Bangkok. I know it's gonna be Songkran (hottest day of the year) and the weather all year round in Bangkok is generally hot. I've seen couple of single houses which I'm interested in but when I entered the house, it was extremely hot (even with 1 A/C turned on). I know I'm gonna spend a huge amount on electric bills to cool down the house during the day and also night time.

Therefore, I've read all of your comments above and found it very interesting. Please forgive me as I've zero knowledge in solar energy and seriously, all the above sounds alien to me. I've heard many comments from people around saying solar energy is expensive to install and does not justify the cost of paying for grid electric. Is this true? Also...I've searched google and could hardly find any interesting installer in Bangkok. If you have any recommendations, it would be so kind of you to share the info.

Insulation. Sounds a whole lot to me. As though the entire house needs to be thorn down for the matter. Then again, it sounds really logically to do it as the heat in Bangkok is burning. In that case, if I'm going to insulate my new house...do I need to re-do the walls around, the ceilings and roofs? A friend of mine told me that tinting the many window glasses in this house would be a bad idea. Somewhat creates a green house effect...I've no idea. Anyone knows bout this? Also, any recommendations on the installers in Bangkok?

Thanks in advance.

Btw...the passed few months was terrible. It was already extreme hot during the day and by night, I had to buy ice blocks to dump it into the water tank so that my family and I can take cool showers. I know it sounds crazy but it's better than taking hot showers on a hot day.

Are you sure that Thailand is the right choice for you? Do you really want to invest in a property on a place where you find the climate unbearable?

Well...besides the weather and the red shirts now, everything is fabulous here. I've a business here and already engaged to this cool Thai girl whom I've already known for 5 years. Besides, property in Thailand have very good re-sale value compared to many other Asian countries

[jaideeguy]

I stumbled on this great informative thread only by accidentally searching 'solar power' and would like to revive it with a few questions.

1] the Kaneka panels.....would they [or any other brands] withstand the force of a hail storm?? I've seen larger than grape sized stones here in CM and have seen video on local news of golf ball sized stones up in Chiang Rai....breaking thru roofs, denting cars and breaking windshields. How would they weather a Thai hail storm?? I'd hate to loose thousands of $$'s in a few minutes!!

2] and this directed to dr Naam.....you mention your inverters comming from India....could you please share the brand, price and reliability factor and contact info and any customs/duties paid??

3] No one mentioned or confirmed the customs/duties on importing solar cells to LOS....any info on this very imoprtant detail??

4] and a suggestion to the mods to move this discussion to the DIY home builder forum where it will get some more input from us owner/builders.

Thanks in advance....

JDG

Edited July 20, 2010 by jaideeguy

[jaideeguy]

The following is a copy and paste of a dialogue between me and Dr Naam for those interested.....

jaideeguy, on 2010-07-21 17:16, said:

Naam, on 2010-07-21 16:04, said:

jaideeguy, on 2010-07-21 14:44, said:

Dr Naam.....I just revived an old discussion on solar electric for home use and I requested it moved to the DIY house forum where I thought it would get more attention. One question that I directed to you, I would appreciate info on.....you mention your inverters being from India. could you share specs, contact [link], cost and import duties and your review as compared with the others [Trace, heart etc] out there???Thanks in advance for your input.....either by pm or on the forum topic.Aloha, Jack

i can't provide you with a link Jack and neither have i got any idea about import duties. the only facts i have is the price and the capacity as my units were bought by a friend and i hand carried them to Thailand (i have a home and residence permit in India and go there once in a blue moon).

if i am not mistaken the 1.2kW units were 11,000 Rupees (7,500 Baht) and the 2.0kW unit was 18,000 rupees (12,000 Baht). measurements are 25x25x8cm, weight ~2kilos.

i am very happy with the performance. the switching time when one phase goes is milliseconds and my computers and my other electronics (TV) do not even blink with an eye.

the 1.2kW units need 24 volts and are connected to two batteries (each), the 2.0kW unit needs 48 volts and is connected to 4 batteries.

if i can be of any further help please do not hesitate to contact me. tech thingies are my hobby.

please also provide me with the link of the revived thread.

best regards,

(the mad dog German)

Hi

Thanks for the info so fast. The prices of the inverters sound good.....too bad/no link.

it's a small company which does not even have a website.

I should have asked you if they have a battery charger built in to the units as the Trace and Heart brands do??

yes, charger is built in.

My plan is to do what you did.....use the inverter [2-4kw] to charge batteries and run some separate circuits for tvs, pcs, routers, backup lighting and small wattage appliances........to start with, then may get some of those Kaneka [sp?] solar panels and tie them into the system....all retrofit.

don't forget that the solar panels have to match the the voltage of your battery pack. besides that it will be rather difficult to build some electronic switch gear which cuts public power supply when the panels are charging. in my opinion the initial capital cost for panels and accessories plus the technical difficulties to charge the batteries are not only a zero sum game but will even cause a loss. installing the inverter and the battery pack is a breeze. connecting the inverter output to selected circuits is much more difficult if you have not planned the setup (as i did) when building our house. by the way, an indian converter with a nominal output of 4kW needs a battery pack of 8 units (providing 96 volts). for the needs you described a 2kW unit should do the trick.

Maybe we should add this discussion to the thread....would you mind if I copy and paste the info to share with the other tvidiots out there??

no objection!

chok dee!

[jaideeguy]

to continue this dialogue in public.....

My plan is to start off with a large [self assembled] UPS and agree with you that 2kw would be sufficient for my needs......then later, as [hopefully] prices go down and $$'s fall off the trees, I'll add the solar component.....eventually weaning myself from the grid.

brings up another couple of questions....

1] with my proposed system [charger, batteries, and inverter], I would wire mains going into the inverter and out of inverter to the circuits I want to protect....pcs, routers, tvs etc. 2] That will give me steady 240v with no interuptions??

and switching would be fast enough to not shut down equipment??

3] Is there any danger of frying the charger/inverter with voltage spikes and low voltage??

4] and would my big UPS protect the equipment from voltage fluctuations???

The motivation for this is that we live at 'the end of the line' and have many power outages and voltage fluctuations.....most times a second or 2, sometimes hours.

[electau]

Here is some information that may be of assistance. Where "North" is mentioned replace wording with "South".

　

Stand alone systems

Load

Minimise the electrical load by using the most appropriate energy form for the different energy services in the house. E.g. use LP Gas for cooking and hot water boosting and use direct solar heat gain through north facing windows for space heating (in an energy efficient house). Calculate the load by multiplying the load power (in Watts) by the operating time (hours) to determine the load in Wh or kWh.

System voltage

This is a bit difficult to get it just right, but if the load is less than 1kWh per day use 12V, if the load is between 1 and 3 kWh per day use 24V, if it is between 3 and 6 kWh per day use 48V and if it is above 6 kWh per day use 110V. Remember that if you expand the system at any time you will need to select items with compatible system voltages, so if you anticipate expanding then go for a higher system voltage.

Battery Bank

Divide the load by the system voltage to convert the load into ampere hours (Ah).

Divide the load by the inverter efficiency (typically 85%)

Multiply this adjusted load by the number of days of autonomy (typically 5) and divide by the maximum allowable depth of discharge (typically 70%) to get the battery bank capacity.

Note that new identical batteries of large capacity should be used and try to resist building up the battery bank capacity by using parallel strings. With parallel strings a preferred current route will develop and lead to premature failure of the battery bank.

PV array

Divide the adjusted load by the battery efficiency (typically 90%) to determine what output the PV array must deliver.

Identify the number of peak sun hours (PSH) for your location at the tilt and orientation of the array. This varies from month to month and an annual average figure is generally used. Remember that your main load will most likely be in winter so the array is generally installed at your latitude angle plus 10-150 and will face solar north (different from magnetic north – your installer can determine this for you).

Select the modules that you will use and note the output current at maximum power (this is very close to the current under normal operating conditions). It doesn’t matter much which module you select, but the installation is generally easier the larger the modules.

Monocrystalline, multicrystalline and amorphous modules are all commercially available and their efficiencies and prices vary. However the cost per unit of output power is approximately the same for all modules.

Multiply the module current by the PSH to get the output of each module.

Divide the system voltage by the nominal voltage of each module to determine the number of modules in series.

Divide the array output required by the output of each module to determine the number of parallel strings of modules in the array. Remember you need a whole number of strings so, round the answer to this division up or down.

Inverter

The inverter converts DC electricity from the battery bank into AC electricity to operate the lights and appliances in the house.

Inverter voltage must be the same as the system voltage.

Inverter continuous power should be capable of running those load items that could conceivably be turned on at the same time.

The inverter will have half hour and surge ratings. These should be checked against those larger load items that may run for short periods (half hour) and the starting power and current requirements of and load items which incorporate motors (fridge, vacuum cleaner, power tools etc.).

Charge regulator

The battery bank may be damaged if it is overcharged. The regulator monitors the state of charge of the battery bank and will vary the charging current as the state of charge increases. Initially the charge should be delivered to the batteries as quickly as possible (higher current), but then slow down as the batteries near full charge. If the batteries overcharge they may "gas" (evolve hydrogen) as the water in the electrolyte is broken down into hydrogen and oxygen. This leads to a potentially explosive build up of hydrogen gas (hence the need for a well ventilated battery bank location) and a loss of electrolyte from the battery bank.

The charge regulator must have the same voltage as the system voltage and be able to handle the maximum array current. Use the short circuit current of the array to size the regulator current capacity.

Back up generator and battery charger

These should be sized to be capable of charging the battery bank and powering any dedicated load items running directly from the battery bank at the same time. Chargers are typically in the range of 40, 60 or 80A and generators will vary from 2 to 10 kVA.

Source. Australian National University.

[Naam]

"1] with my proposed system [charger, batteries, and inverter], I would wire mains going into the inverter and out of inverter to the circuits I want to protect....pcs, routers, tvs etc. 2] That will give me steady 240v with no interuptions??

and switching would be fast enough to not shut down equipment??

3] Is there any danger of frying the charger/inverter with voltage spikes and low voltage??

4] and would my big UPS protect the equipment from voltage fluctuations????"

here my answers which are not academic but based on experience:

1/2] steady voltage and extremely fast switching without any equipment (even PC holds) shutting down.

3] i have never experienced voltage spikes but until several months ago the voltage of one or more of the three phases dropped considerably or the phase(s) were gone completely. as i paid a fortune replacing burned pump and aircon relays due to low voltage i had a protection system installed which switches off any phase having less than 200 volts. therefore i can't answer the question. the resident experts Crossy and El Kangorito are more qualified. that also applies to your question #4.

[elkangorito]

My workplace has a PV system, which is directly connected to the grid (PEA power).

I don't know much about cost savings regarding PV/grid systems & nor do I know anything about how the Thai government promotes such systems.

What I do know is the following:

1] The inverter in grid connected systems MUST conform to minimum specs. I will be happy to elaborate on those specs should anyone enquire.

2] Batteries are a contentious issue (not generally used with grid connected systems) & I will be happy to impart my opinion regarding such.

3] The angle of incidence of the PV cells is important. In Thailand, it's not too difficult to determine the most effective 'angle of incidence'.

[electau]

My workplace has a PV system, which is directly connected to the grid (PEA power).

I don't know much about cost savings regarding PV/grid systems & nor do I know anything about how the Thai government promotes such systems.

What I do know is the following:

1] The inverter in grid connected systems MUST conform to minimum specs. I will be happy to elaborate on those specs should anyone enquire.

2] Batteries are a contentious issue (not generally used with grid connected systems) & I will be happy to impart my opinion regarding such.

3] The angle of incidence of the PV cells is important. In Thailand, it's not too difficult to determine the most effective 'angle of incidence'.

What promoters of photo voltaic (solar) panels forget to mention is how much electrical power is actually generated over the period when the sun is shining directly on the panels.

Peak sunlight is not constant over a day. Output is restricted by cloud cover or heavy cloud cover with rain.

Question.

What is the output of a 1 kW array over an average day from 6 am to 6 pm and what is the output over 365 days? Output measured in kWhs voltage will be DC.

One may obtain up to 6 kWhs per day, this is how they promote them, the real figures are somewhat different.

Tracking of panels may not be feasable in many installations unless very large.

What is required is a table of sunlight values on the panels versus output voltage.

Grid connected systems are interlocked so that feedback is prevented for safety purposes and isolation for maintainance of the network.