Solar Powered Home In Thailand

[manarak]

Ok, I have looked at the problem before, but my calculations were wrong.

Common sense says that solar power should work well in Thailand, since the insolation is high.

I would like to go through the whole topic of solar power in Thailand, step by step, to fully understand everything about it, especially the economics.

The following steps are needed in my opinion:

- determining the optimal panel type

- tracker or not

- first calculations: panel costs, produced power, installation costs

- what can batteries do? i.e. how much power produced during the day can be used during the night?

- sizing the system: how much panels, how much batteries?

- other questions: can such an installation run water pumps, AC units?

- final financial calculations

Let's begin with the climate and the choice of panels:

here is exact data about the climate:

http://www.gaisma.com/en/location/pattaya.htm

(you can even choose exactly your location)

I have read that thin-film panels perform better at high temperatures.

Then the cheapest panels I found so far are 60W Keneka thin-film panels rated at 1.37 USD/W here:

http://www.affordable-solar.com/solar-pane...-the-pallet.htm

But I don't know if those are the best and I don't know how much power will be really produced under real conditions in Thailand.

Also, there is the question about trackers. it is said that trackers can improve panel performance by 20 to 50% ? Obviously, the Kaneka panels at 60w will need a large surface, which would need more trackers. So there is probably an optimum somewhere between the number of trackers and the installed panel surface (depending on wattage).

And then the trackers probably need maintenance, while fixed panels can be left more or less alone...

Aaaah, choices, choices.

Does anyone have information on this?

This would be step 1.

[gregb]

Don't mistake my reply for being anti solar. I would love to see a financial analysis where it really made sense. But the fact is, at today's prices, it can not compete with grid power. The problem isn't the level of insolation in a given area. The problem is the EROEI of solar power in general. It is not possible for a diffuse energy source like solar to compete effectively with a highly concentrated energy source like fossil fuels. Don't expect a financial analysis to ever be beneficial vs just using grid power.

Your cheap solar panels are great. Any idea how much it will cost to import them? I can't find anyone who has ever done it, and local suppliers are still charging 200 baht/watt. It would seem there is a reason for this, but I don't know what it is. So if you can verify how much it costs to import reasonably priced panels, please report back to the group. Until then, I think the $1.37 price you are quoting is not realistic. I would increase that by a factor of 4, but I would be happy to be proven wrong here.

If you can actually get solar panels at $1.37/watt, tracking does not make sense. It will cost more than $100/panel to implement the motors and electronics necessary to track the sun. For a 60 watt panel, that means even at a 50% increase in daily power you are paying over $3/watt for the tracking mechanism, not to mention the increased maintenance associated with it. It is simply bad economics. Just fix the panels for the noon time sun and be done with it. Add more panels if you need more power. It's cheaper.

For batteries, your best bet is nickel iron over the long term. These will outlast your solar panels. They have a high self discharge rate, but for solar you generally don't need to hold a charge for more than a few hours so this argument is irrelevant. Properly maintained you will never need to replace your battery bank with this technology. I have never found anyone in Thailand who sells them however. They are readily available from China, but again you have that import problem.

If you would be so kind as to report back to TV with your findings I will follow your project with interest, but I have very little confidence your results are going to be interesting for the vast majority of people. PV solar is great for off grid solutions or for people willing to pay more for green energy, but otherwise it is largely a wasted effort.

If you want something that may actually prove to be cost effective in the long run, check out connecting a GEK gasifier to a standard generator and use biomass to generate electricity. It will require you to cut wood everyday, requires more land area, only works if you don't care about the generator noise and isn't nearly as maintenance free, but it can compete economically today with grid power. It doesn't suffer on cloudy days, and can continue to run all night if you want. Biomass is nature's way of concentrating solar power.

BTW, I don't know where you read that thin film panels perform better at higher temperature. High temperature is universally deadly to PV efficiencies. That is why PV solar concentrators enjoy only limited success. Please post your source for this so we can understand where this idea is coming from. I've never heard of it before.

Edit: Forgot to tell you...for nickel iron batteries, plan on 60% of the watt-hours generated by your panels actually being available to you at the batteries. You can get this up to about 80% by using a different battery technology, but you pay for that. With the more exotic technologies you'll need to replace the batteries every 5 years or so. Unless you have a real weight/size restriction, simple economics will cause nickel iron to win every time.

Edited February 26, 2010 by gregb

[manarak]

Thank you Greg for those very helpful comments.

I think the panels can be imported privately.

I am not aware there are any specific taxes on the import of solar panels in Thailand, so I suppose just add 7% to the price, or maybe less in cooperation with your customs officer in whom you trust :-)

about the batteries, you say that within some hours after the power was produced, I will get out of batteries 60% of the power they used to load?

so this means if I want to get 40kWh from the batteries during the night, I will need to produce 67 of extra energy during the day to load the batteries.

So here another calculation will be needed to determine the return on stored power, also taking into account the costs of batteries.

What kind/size of battery installatin is needed to store 40kWh?

and then there is the inverter.

how much energy is lost the inverter? 5 to 10%?

So what we need to do now is estimate how much fixed Kaneka panels are needed to obtain a net output (after inverter) of 100kWh, given the insolation data.

operating temperature: here is what is said about the Kaneka panels:

60 Watt, Kaneka, G-SA060

The Kaneka GEB is a thin film silicon solar panel that has been designed for both grid connected and remote power applications.

The Kaneka panel has been used extensively Australia wide and there are more than 10,000 panels on Australia roofs.

Features:

- Exceptional high temperature tolerance - a crystalline solar panel decreases in power output over twice as rapidly as the Kaneka GEB. Kaneka Silicon PV's generated watt-power is about the same as that of other crystalline silicon PVs during the winter months, but in summer, the Kaneka Silicon PV generates significantly more power compared to other crystalline silicon PVs. Kaneka modules can deliver maximum performance during summer when the electricity is needed most for air-conditioners in houses and offices. Source: "NEDO/Ritsumeikan University Demographic Module Field Test and Operational Analysis" presented at the International PV SEC-11, Sapporo, Hokkaido, Japan, 1999. Installation location: Kusatsu, Shiga Prefecture Japan Slope angle: 15.3 degree Exceptional performance in low light and shady conditions - a regular crystalline panel will cease to function when shade falls on part of the panel. With the Kaneka LSU, shade will only impact on the portion of the panel the shade obscures. Additionally, Kaneka solar panels have superior light absorption per nominal watt power. They absorb more of the sun's spectrum. Compared with mono-crystalline silicon PV modules or poly-crystalline silicon PV modules, Kaneka generates considerably more power per nominal watt power. Assuming that the total solar radiation per year (1.323kWh/m2) is 100%, Kaneka Silicon PV can produce 90.95% of actually generated watt-power, much higher than that of other crystalline silicon PVs (80 to 84%).

[gregb]

Someone else up really late at night on a Friday. Glad to know it isn't only me.

I think the panels can be imported privately.

I'm serious when I say let us know if you do it. The local providers still think this is worth 200 baht/watt. I'd love to know why. If they are out of their mind I would take great pleasure in telling them so.

about the batteries, you say that within some hours after the power was produced, I will get out of batteries 60% of the power they used to load?

so this means if I want to get 40kWh from the batteries during the night, I will need to produce 67 of extra energy during the day to load the batteries.

Correct. You can actually expect about a 10% loss in the charge controller, and about 70% efficiency when charging the batteries, so combined that amounts to 63%. I usually round down for these things.

What kind/size of battery installatin is needed to store 40kWh?

Ouch! That is really big. It's simple math though. If you assume 80% depletion, you will need a 1040 Amp-Hr 48 volt system. That won't be cheap. You are looking at minimum 1 million baht (probably more) not including shipping or import duties. Lead acid may be cheaper up front, but again you'll have to replace them in a short time. Also, you can really abuse nickel iron batteries. You can discharge those things to only 20% continuously and still expect good performance for multiple decades. Lead acid would require not going below 50% to get more than 5 years of service.

It's your call of course. That kind of storage is going to cost you no matter what you do. You might consider pumped hydro and a microhydro generator when you get up into those levels. Efficiencies will be even worse, but capital costs might be lower. It's generally cheaper to buy special purpose low power appliances than it is to store power.

and then there is the inverter.

how much energy is lost the inverter? 5 to 10%?

So what we need to do now is estimate how much fixed Kaneka panels are needed to obtain a net output (after inverter) of 100kWh, given the insolation data.

Well, if you're talking 40 kWh storage, then your power usage is going to be high. You can afford to get a really good inverter. Probably can get up to 95% at high current.

Do you mean 100 kWh per day? That's a really big system. You setting up a factory? Most places in Thailand give about 4.3 hours of direct sunlight equivalent on average. You'll get just over 55% efficiency all the way through during the night, and about 80% during the day, so assuming you want 40 kWh during the night and 60 kWh during the day, your average efficiency will be 70% . So if you don't worry about cloudy days, you'll need 33 kW of panels. So even with your low cost panels, that is $45K USD just for the panels, and you have made no provisions for cloudy days, unless the 100 kWh spec already includes that.

Regarding Kaneka panels and thermal performance:

OK. Sorry. Misunderstood what you meant. They are saying that their panels tolerate heat better than standard poly crystaline panels, but their absolute efficiency is still better in the cold. Can't speak for the company because I have no experience with them, but I could believe that such a claim is possible. My only advice would be to try it out first before taking their word for it.

[Naam]

manarak: What kind/size of battery installatin is needed to store 40kWh?

greg: Ouch! That is really big. It's simple math though. If you assume 80% depletion, you will need a 1040 Amp-Hr 48 volt system. That won't be cheap. You are looking at minimum 1 million baht (probably more) not including shipping or import duties. Lead acid may be cheaper up front, but again you'll have to replace them in a short time.

a lead acid 48V/1040A is considerably cheaper and even though the life time is shorter it beats financially the living beejesus out of any other storage. the system can be easily built with 8 truck batteries (each 160Ah) at a cost of ~ 35,000 Baht (inverter not included). it's not rocket science to compare these cost with an initial investment of THB 1 million++. i run since two years two 24V and one 48V systems each with a 2000W inverter. total price for 24V/320Ah including inverter THB 18,000 and for the 48V/640Ah THB 28,000 but i don't use solar but conventional power for charging.

[Naam]

Don't mistake my reply for being anti solar. I would love to see a financial analysis where it really made sense. But the fact is, at today's prices, it can not compete with grid power. The problem isn't the level of insolation in a given area. The problem is the EROEI of solar power in general. It is not possible for a diffuse energy source like solar to compete effectively with a highly concentrated energy source like fossil fuels. Don't expect a financial analysis to ever be beneficial vs just using grid power.

all said! anything else (at present times) is fiction or wishful thinking.

[policot]

Good morning,

My house in Isaan is powered only by solar and a wind turbine when the weather is cloudy.

I have 4 x 80 W panels on a Etatrack 400 for pumping water with a Lorentz PS 150c deep well pump (lift 22 m, 5m³/ hour max) with 2x batteries 100A

Also 4 x 120 W panels on a Etatrack 400 and a 2000W windturbine for electric supply for the house, withe 4 x 130A batteries. The house is very good isolated, dubbel walls, and White roofing. I put Radiant cooling mats in some walls, but they are not connected yet, because I'm looking for a water/ water cooling system, because the water from the well is about 27°C in hot season, I should have about 20 °. Normally the water from the well should go trough the Radiant coolig mats in the walls before irigate the garden. The wind turbine works nearly each day, minimum 2 or 3 hours...., sometimes even at night...

If you want more information, you can contact me at [email protected]

[Naam]

Good morning,

My house in Isaan is powered only by solar and a wind turbine when the weather is cloudy.

I have 4 x 80 W panels on a Etatrack 400 for pumping water with a Lorentz PS 150c deep well pump (lift 22 m, 5m³/ hour max) with 2x batteries 100A

Also 4 x 120 W panels on a Etatrack 400 and a 2000W windturbine for electric supply for the house, withe 4 x 130A batteries. The house is very good isolated, dubbel walls, and White roofing. I put Radiant cooling mats in some walls, but they are not connected yet, because I'm looking for a water/ water cooling system, because the water from the well is about 27°C in hot season, I should have about 20 °. Normally the water from the well should go trough the Radiant coolig mats in the walls before irigate the garden. The wind turbine works nearly each day, minimum 2 or 3 hours...., sometimes even at night...

If you want more information, you can contact me at [email protected]

have you thought of the condensation problem? drip... drip... drip...

[jaapfries]

Don't mistake my reply for being anti solar. I would love to see a financial analysis where it really made sense. But the fact is, at today's prices, it can not compete with grid power. The problem isn't the level of insolation in a given area. The problem is the EROEI of solar power in general. It is not possible for a diffuse energy source like solar to compete effectively with a highly concentrated energy source like fossil fuels. Don't expect a financial analysis to ever be beneficial vs just using grid power.

all said! anything else (at present times) is fiction or wishful thinking.

Conclusion: It is not economically viable (at the current power price levels in Thailand) to consider putting in a full PV-System to run a house; that much is obvious. However; there is a way to cut down substantially on an individual house's power consumption:

1. A simple and inexpensive PV-System to run some lights, fans & appliances etc. (buy Low Power Consumption Appliances!)

2. A simple, but very effective Geothermal Cooling System (so; no more expensive A/C unit)

3. A simple, yet effective Solar Hot Water system (so; no more expensive power used to heat up water)

By doing something like this, an average house would save the environment in excess of 4 Metric Tonnes of CO2 per year, whilst saving the ower dramatically on power-bills !

Overall ROI on a combination of these elements ? Approx. 4~5 years.

Cheers,

JGK/Pattaya

[Naam]

"A simple, but very effective Geothermal Cooling System (so; no more expensive A/C unit)"

that involves a lot of digging and i don't believe that it is not more expensive than conventional aircon. you still need a heat-exchanger, separate pumps for each unit and of course indoor units as well as a distribution system. geothermal heating is a different animal because the basic heating system exists already. correct me if i am wrong and elaborate on the functions as well as the installation.

a viable alternative is a deep well which serves water-cooled aircon units. existing a/cs can be converted by adding a heat-exchanger, a pump for each unit and an overall water distribution system with solenoid valves triggered by the indoor units. all in all not advisable for a technical layman (because of the maintenance) and/or somebody who wants to save money.

the setup is not cheap but a converted aircooled a/c unit with a nominal capacity of 18,000 btu/h can -watercooled- deliver up to more than double the rated capacity depending on the water temperature (in my case a steady 19ºC, cool and hot season, depth 39m). a big problem is to find a qualified contractor who will convert the units. i have one watercooled (by pool water not by well water) unit 36,000 btu/h which serves a dual purpose, namely cooling down our pool area and heating the pool from october till march when the water is too cold because the pool is not exposed to the sun. in my case i found (after months of searching) a contractor which converted the unit exactly according to my specifications. i am sure that a normal contractor could do the job too but language is a huge problem.

[Naam]

My house in Isaan is powered only by solar and a wind turbine when the weather is cloudy. I have 4 x 80 W panels on a Etatrack 400 for pumping water with a Lorentz PS 150c deep well pump (lift 22 m, 5m³/ hour max) with 2x batteries 100A.

If you want more information, you can contact me at [email protected]

tiny correction. the PS 150c pumps 9l/min @ lift 22m = ~2m³/h

[manarak]

Thanks for replying to this thread.

My goal here is to "find out" about solar power economics in Thailand, in such a way that the calculations can be used not only by me but also by other people to find out the financial yield of such a solar project, now but also in future.

So, if in future panel prices, efficiency, storage efficiency, inverter efficency and prices change, one could use this study and replace a few variables and find out if the new technology is economically better.

About the size of the system, I look of course at my own estimated need.

We are talking about a big house with big pool and 6 people living in it.

I will use the best technology I can to reduce power consumption (i.e. LEDs, efficient AC units, modern TVs and Fridges/Freezers, etc.), but nobody in the house will go out of their way to save power (i.e. turn AC to 29 instead of 25/26, take shorter showers, switch on less lights, etc.).

I attached a picture of a table in which I calculated some time ago the house's power needs.

In summary, I estimated a bit less than 150kWh a day, whereof 50kWh would be used in the night, which would lead to a power bill of 15750 baht per month if we assume 3.5 baht per kWh.

(please tell me if I am way off with these estimations, or if the baht price per kWh from the grid is wrong)

I also assume that it is not possible in Thailand to sell power to the grid.

...now to the first calculations:

* the rated efficiency of Kaneka's G-SA060 is 6.3%

from: http://www.solarpowerbeginner.com/kaneka-solar.html

=> I interpret this figure as meaning the Kaneka module will output as power 6.3% of the total solar energy it receives, under optimal conditions (i.e. 25°C).

* the Kaneka panel has a Maximum Power Temperature Coefficient (% per °C) of -0.26

=> if I understand correctly, this means that the power output of the panel will decrease by 0.26% for every celsius degree away from the optimum of 25°C

So can we assume the panels will be operating in Thailand at 45°C ? or even 50°C ?

Let's take 25 degrees difference to be sure, so: 25*0.26= 6.5%, so the net panel efficiency will be not 6.3%, but rather 6.3-6.3*0.065 = 5.9%

* PTC rating of 57w according to http://www.gosolarcalifornia.ca.gov/equipment/pvmodule.html

=> This figure means that in real life conditions the Kaneka panel outputs only 57w, which means there is a 5% unadvertised loss, which should also be substracted from the advertised efficiency.

* then the fixed panel position vs. tracker.

Common sense says that trackers will have the most benefits in countires where the sun's way in the sky varies greatly. Trackers are said to improve performance by 20 to 50%, so if I say in Thailand, the sun doesn't change its trajectory very much, we could say 25% of power are lost because of the fixed panel position.

* the good (and pricey) inverter will shave another 5% off.

So, the total efficiency to reach the house power system will be:

6.3-6.3*0.05 = 5.985% (PTC rating)

5.985-5.985*0.065 = 5.595975% (temperature)

5.595975-5.595975*0.25 = 4.19698125 % (fixed panels, no tracker)

4.19698125-4.19698125*0.05 = 3.98 % (inverter loss)

So, now we can take the insolation data:

http://www.gaisma.com/en/location/pattaya.html

and calculate the net daily output per square meter of panel in the different months:

insolation kWh/m2panel output kWh/m2jan5.060.474628feb5.450.51121mar5.610.526218apr5.620.527156may5.010.469938jun4.70.44086jul4.550.42679aug4.550.42679sep4.640.435232oct4.660.437108nov4.860.455868dec4.860.455868

average: 0.4656 kWh per m2 of panel

so here we can calculate the needed surface of panely for a given power requirement:

for producing 100 kWh in daytime, we need in average 100/0.4656 = 214.77 square meters of installed panels.

the size of the kaneka panel is 39 inches by 39, 1 inch = 0.0254 meters, => 0.9906 * 0.9906 = 0.9813 m2

needed panels for 100 kWh = 214.77/0.9813 = 218.87 => 219 panels.

Price of a pallet of 25: 2055 USD

http://www.affordable-solar.com/solar-pane...solar-panel.htm

9 pallets: 18495 USD (without shipping and Thai sales tax).

Please review this post, tell me if I wrote bullshit.

[manarak]

wow, look here:

http://sunelec.com/

the Kaneka panels at 0.98 USD per Watt!!!

$ 58.80 for one, x 219 = 12877.2 USD !!

[gregb]

So, now we can take the insolation data:

http://www.gaisma.com/en/location/pattaya.html

and calculate the net daily output per square meter of panel in the different months:

You're making this way more complex than it needs to be. Panels are generally rated for full sun, which is approximately 1300 Watt/m2. Based on the insolation data you have provided above, your worst month receives 4.55 kWh/m2. Thus, a 60 watt rated panel will produce approximately 4.55/1.3*60 = 210 watt-hours per day during the worst month.

Therefore, to determine the number of panels you will need, simply divide your estimated usage per day in kWh by .21 and you will have your answer. If you need 100 kWh at 70% efficiency, you need 100/.7/.21 = 680 panels.

Note, this only works if you have infinite storage capacity, which you don't. There could be weeks where you have cloud cover and drop far below the mean. You will either need to cut back on power during this time, or supplement with another energy source.

You can increase this by tracking the sun of course (this effectively makes your panel look larger, i.e. grabs more sun than is normally incident on its footprint), but as stated above, it is not cost effective to do that given your panel cost.

Yes, I am simplifying. But it is a simplification that works very well. You are a factor of 3 too low with your panel estimation.

[manarak]

The Kaneka panels are rated 57w @ 1000 w/m2

So this would be 4.55/1*57 = 260 W

Where does the 70% efficiency figure come from?

[gregb]

The Kaneka panels are rated 57w @ 1000 w/m2

So this would be 4.55/1*57 = 260 W

Where does the 70% efficiency figure come from?

OK. So the calculation is easy then. For 100 kWh, you would need 100/efficiency/.26.

The 70% comes from the calculation earlier in the thread. You stated you wanted 40kWh at night, and 60 kWh during the day. The night efficiency which requires charging batteries is approximately 55%, and the day efficiency is approximately 80%. You can substitute your own numbers if you find these too low. Therefore, average eff = .4 *.55 + .6 *.8 = 70%.

Based on that you need 550 panels.

[manarak]

oh, the 100kWh was a figure just for the day, not night. Therefore no batteries involved so far.

I was just looking at the "producing energy" part, basically what comes out of the inverter.

so that would be 100/.08/.26 = 480 panels

so, is the rated panel efficiency of 6.3% wrong then?

[Bizz]

in view of the amount of hesitation and fumbling maybesolar the op might want to read up a little more this should keep you all busy.

[Naam]

oh, the 100kWh was a figure just for the day, not night. Therefore no batteries involved so far. I was just looking at the "producing energy" part, basically what comes out of the inverter.

with all due respect Manarak but that is science fiction. you can't mix solar power with grid power. it's either or. moreover, it is virtually impossible to run high consuming electric items without drawing constant current from batteries.

[Bizz]

oh, the 100kWh was a figure just for the day, not night. Therefore no batteries involved so far. I was just looking at the "producing energy" part, basically what comes out of the inverter.

with all due respect Manarak but that is science fiction. you can't mix solar power with grid power. it's either or. moreover, it is virtually impossible to run high consuming electric items without drawing constant current from batteries.

Naam as i respect your Analiese of posts and i know you to be a very knowledgeable person in this field i know you possess influential knowledge, this i feel needs proper Annalise as in the further we need influential people to pursue its advancement.

[Bizz]

my apologies i forgot scribe here

in a world where we find ourselves so undermined, by world events we have to look at our selves to find the truth it is there and to strive for it's again.

[Naam]

About the size of the system, I look of course at my own estimated need.

1. We are talking about a big house with big pool and 6 people living in it.

2. I will use the best technology I can to reduce power consumption (i.e. LEDs, efficient AC units, modern TVs and Fridges/Freezers, etc.),

3. I attached a picture of a table in which I calculated some time ago the house's power needs. In summary, I estimated a bit less than 150kWh a day, whereof 50kWh would be used in the night, which would lead to a power bill of 15750 baht per month if we assume 3.5 baht per kWh.

(please tell me if I am way off with these estimations, or if the baht price per kWh from the grid is wrong)

4. I also assume that it is not possible in Thailand to sell power to the grid.

in reverse order:

4. on paper that possibility exists since a few years, in reality you can forget about it. moreover, your high demand clearly makes it impossible to sell surplus power except if you invest an additional few million and sell at a huge loss.

3. 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.

2. using most energy efficient gadgets bring considerable savings for somebody who draws 5-10 kWh/d. in your and my case the savings are negligible. as airconditioning is a major factor you should rather concentrate on excellent insulation of your house but not taking into consideration most of the myths which are presented by thai builders or in this forum. perhaps you could list what you are planning in this respect and i will do my best to comment and assist.

1. answered under "3".

[Bizz]

thank you Namm. i,m here too stay.

[Naam]

Manarak,

i just looked at the consumption estimate you posted and realised that you plan only 4 aircon units. please elaborate what you consider a "big" house.

quote: "We are talking about a big house with big pool and 6 people living in it."

[hazz]

I am very unsure about either the money saving or eco credentials of solar electricity. One must remember that many solar cell technologies require vast amounts of energy to manufacture. Then their are the issues of just how many sqm of panels you need.

An alternative approach would be to abandon solar electricity and use solar heat to create hot water. This water can be used for the usual, cleaning and bathing. but more importantly it can also be used to drive air conditioning.

This company manufactures units which can provide chilled water using any source of hot water over 70C

http://www.yazaki-airconditioning.com/en/p...ed_chiller.html

This company manufactures the solar panels needed to provide hot water

http://www.himinsun.com/

An artical about a 10 tonn solar air conditioning system at King Mongkut’s University of Technology Thonburi

If you are interested in off grid housing in thailand, a member of the architecture department at Chulalongkorn University built such a house for about 3 million Bhat about 7 years ago. There is a detailed artical about it in the department's in house magazine and web based artical at architecture week. One thing this guy pointed out that the main issue with solar electricity is finding enough space to put the solar PV panels; rather than the cost of the panels, he ended designing the house and its grounds to minimise the external temperatures around the house and together with heavy insulation kept his aircon requirements to 9000 BTU for the whole house if my memory is working

[manarak]

Manarak,

i just looked at the consumption estimate you posted and realised that you plan only 4 aircon units. please elaborate what you consider a "big" house.

quote: "We are talking about a big house with big pool and 6 people living in it."

Naam, thank you very much for all the knowledge you pump into the thread!

It really helps me to understand the whole solar tech better.

I would like to point out that yes, I am a newbie about solar power.

I tried to read about the tech, but I never found anything explaining the gritty details.

I would like to understand the details in order to do a full analysis, and be able to change parameters of the calculations depending on technological choices.

So, to do this I need to link all components of the solar energy system by formulas that work, from one end to the other.

I am capable of doing maths and understanding physics, so this is just a question of getting the correct info together.

So thank you very very much.

The first mystery for me is now why the bottom-up calculation based on panel efficiency gives another result than the calculus based on rated Watts (PTC)?

I cannot locate a logic flaw in the calculations, so this would seem to indicate a variable is wrong.

About the consumption estimate:

it is about a house I have yet to buy and to insulate.

I think it is the best thing to find out about solar power before building or buying a house, since I can then ponder the advantages or disadvantages of a given house regarding solar power.

Thank you very much for posting your power consumption.

The equipment you list matches well with what I had in mind.

I listed only 4 AC units because I initially started with listing the probable units in the bedrooms, the atrium, etc. but then I simplified by putting 4 1000 W units at 50% use, which is unrealistic, but which I thought would simulate for 10 or 12 smaller units in intermittent use.

I also was more generous in my estimate, because I wanted to avoid bad surprises in my power budget.

I will now take your effective power consumption as an estimate for mine.

On a side note, I am writing this with my left eye hold in place by a big plaster, I've got conjunctivitis on both eyes plus an infection of cornea in the left one.

Looking on the monitor is painful, but looking at the keyboard is ok. Sorry if I don't correct all typos.

with all due respect Manarak but that is science fiction. you can't mix solar power with grid power. it's either or. moreover, it is virtually impossible to run high consuming electric items without drawing constant current from batteries.

Can you elaborate on the impossibility to draw power from the grid?

If I've got a solar system, and it doesn't cover my needs fully, where would the rest of power come from?

Edited February 28, 2010 by manarak

[Naam]

"Can you elaborate on the impossibility to draw power from the grid? If I've got a solar system, and it doesn't cover my needs fully, where would the rest of power come from?"

that's a misunderstanding Manarak. of course you can use solar power and grid but the two sources have to be separated and switched with gear according to demand or availability which is a tedious procedure if done manually and a dangerous as well as expensive one when done automatically. "dangerous" means that a failure of automatic switching might destroy you solar equipment in the blink of an eye.

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.

a feasible solution would be to connect only those gadgets to solar which do not have a specific demand at specific times. howver, i can't think of others than the ones i mentioned above.

[Naam]

"I listed only 4 AC units because I initially started with listing the probable units in the bedrooms, the atrium, etc. but then I simplified by putting 4 1000 W units at 50% use, which is unrealistic, but which I thought would simulate for 10 or 12 smaller units in intermittent use."

that makes sense. when selecting your units don't believe what the average contractor recommends. virtually all of them are interested to sell you overdimensioned units which of course will cool down your areas but lack "latent" cooling because the shorter run times do not dehumidify the area sufficiently. as most people have not idea what "latent" cooling means i'd like to say a few words in layman terms and start with "latent cooling represents 40% of cooling capacity". a too big aircon [e.g. 24,000 btu/h] which cools a certain area to [let's say] 26ºC with rather short run times does not dehumidify the air as one with half the capacity which will reach with longer run times the same temperature but reduces relative humidity to a much higher degree. 26ºC @ 80% rel. humidity feel like 28-29ºC whereas 26ºC @ 60% rel. humidity (comfort zone) feel OK.

facit: if you can afford the initial investment, select more low capacity units and place them strategically. your air distribution is much more balanced and in the long run you even save energy.

[Naam]

"About the consumption estimate: it is about a house I have yet to buy and to insulate. I think it is the best thing to find out about solar power before building or buying a house, since I can then ponder the advantages or disadvantages of a given house regarding solar power."

i don't see a pressing need for that. the only thing advisable is that you set up your electrical distribution as detailed as possible (i have 64 different circuits on individual breakers) and of course the feed from [future] solar to your distribution panels. adding PV at a later stage is not a technical but a financial matter.

[Naam]

"The first mystery for me is now why the bottom-up calculation based on panel efficiency gives another result than the calculus based on rated Watts (PTC)? I cannot locate a logic flaw in the calculations, so this would seem to indicate a variable is wrong."

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