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Posted (edited)

It is very likely that I will be building a house in Nakhon Ratchasima next year. I want to install a full solar power system as part of the build. I am aware that it may take years to get any payback on the outlay - I am not doing this to save money, my reasons are environmental. The house will almost certainly be much the same as my current property and therefore have much the same power requirements - i.e.

 

2 x TV's

3 x Aircon units

1 x Electric oven

1 x Microwave

4 x Ceiling Fans

Low energy LED lighting throughout

 

The house will be occupied by 2 adults and one child.

 

Of course there will be all the other smaller things that are normal for a house (western lifestyle) but clearly, it is most unlikely that all these things will be switched on at the same time. For example, the electric oven will not be used much but the grill in it will be used more. The aircon units serve 2 bedrooms and 1 living room - living room on during the day, bedrooms on at night. However, much of the time, if the bedrooms are first cooled by the aircon, the ceiling fans are sufficient. Walls and loft space will be insulated and all windows and doors will be double glazed and fitted with low E glass.

 

I insist on hot water and will need to decide what sort of system I am going to put in to this house. I installed an Air Source Heat Pump system in my current home and so far I am very pleased with it. It enables me to have constant hot water supplying the thermostatic shower valves in each shower (2) and the kitchen.  I would very much like to install the same system in the planned house and I think this will probably mean I need a higher output solar system. The current heater is very similar to this one and is the smallest one on the list - 200l storage tank and stated as having an average power input of 1.2kw.

 

http://wordpress.utomedia.co/cripton/products/air-source-heat-pump/domestic/#.XVZ1nXt7nIV

 

I know very little about solar power - I believe it produces DC electicity and therefore needs a converter. The house will also be connected to the mains electricity supply so some form of coupling/automatic changeover device must be required?

 

I realise that power usage is very much a 'how long is a piece of string' situation but there must be some 'average' figures. I don't make huge demands on power but given that I am a westerner, I am likley to use more than the average Thai - i.e. aircon.

 

What I would like to know is - what size of solar system will I require and how many square metres of panels will that system require? Clearly the cost of such a system and associated switchgear is also paramount.

 

I'm not sure if I will fit the system myself (in conjunction with an electrician) yet - clearly I would need a cost comparison against a contractor to be able to make that decision. Any recommendations for a good solar power supplier/installer would be appreciated.

 

Edited by KhaoYai

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Posted (edited)

Assume you will get between between 1/2-1 unit a day per 330w solar panel (2m x 1m).

(I get 1/2 but another poster thinks he get 1)

Then work out how many units you use a day to calculate the number of panels you need.

Panels cost 4k, grid tie inverter cost 4k and can take 2 panels.

You can buy more expensive GTIs, but the costs remain fairly constant.

Edited by BritManToo
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Do you have grid power at or near your site?

 

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53 minutes ago, Naam said:

good luck with "full solar" :crying:

It's a rainy day. Sunshine girl.

It's a smoggy day. Sunshine girl.

It's a cloudy day. Sunshine girl.

Lessons to be learnt. Sunshine girl.

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7 hours ago, Crossy said:

Do you have grid power at or near your site?

 

Yes, there's an existing house on the site at the moment but its coming down.

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Posted (edited)
2 hours ago, tjo o tjim said:

First thing you need to do is maximize efficiency and passive effects. A solar water heater might be your best approach from a cost perspective, but a heat pump hot water heater will provide some cooling as a benefit............

Thank you for your entire post but its getting a little technical for me.......batteries? I had no idea solar systems use batteries. I'm not so sure that any system on anything that uses batteries is so good for the environment. 

 

I'm not convinced for example, that electric cars that use batteries are quite the environmental saviour we are led to believe.  Its just possible that in reducing emmisons from cars, we may be solving one environmental problem but creating another - namely the replacement and disposal of batteries. Not forgetting of course, that the electricty used to charge the car's batteries is very liklely to be produced at a power station that emits gases that contribute to climate change. I have no idea of the figures but I wonder how much we save (total environmental cost) by using electric cars? - taking into account the environmental cost of producing, replacing and disposing of batteries + the environmental cost of generating the electricty needed to charge those cars. They may well still be a better alternative but electric cars are not without environmental costs.

 

A neighbour of mine was full of herself, claiming she was now totally 'green' because she had bought an electric car - that was until I pointed out to her that the power station serving our area of the UK still burns coal. She's not quite as smug now.

 

Still, I want to do whatever I can - I think each and every one of us has a moral duty to our children and grandchildren to try and do something to a avert the catasthrope that both ourselves and previous generations have set in place.

 

16kw? Really? I haven't done a lot of research but most of what I've read so far seems to indicate that 4kw is enough for a small house. I don't intend switching all of my appliances on at the same time.

 

There's still a lot of planning to do and of course I need to gain other views but its looking like a partial system may be better?

 

BTW, my current air source heat pump does emit some colling air but its an external unit so the only thing it cools is the garden.  Maybe a unit at the new house could be sited where its cooling could be utilised but them things ain't quiet when they're running you know?

Edited by KhaoYai
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7 hours ago, BritManToo said:

Then work out how many units you use a day to calculate the number of panels you need.

How many units = 1kwh? Or is that one unit?

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Posted (edited)

One unit is one kWh. For a house of your size I'd say around 5kW inverter size should do the trick. You can size your panels (yes they generate DC hence you need that inverter) a bit higher than the inverter peak output, usually 10% are fine. So 5.5kW in panels. Depending on the wattage of the panels that'll be 14-17 panels. Each as mentioned about 1x2m with a bit of space between them. Calculate 2.5sqm per panel roughly. Make sure they are facing southward and are not all too much tilted differently than the latitude of your location. Too lazy to look up the one of Korat but I'd guess around 16 degrees.

 

Forget batteries, they are too expensive and break way too easily here if connected to the funny grid unless you have a voltage stabalizer.

 

You can connect it to the grid (grid-tie) but the PEA wont like it unless you sign up for their rooftop solar program which pays you 1.8THB per unit that you send them. It's monetarily more efficient to not tell them and just let the meter spin backwards but you'll have to keep an eye on that meter and make sure you never run lower than the previous value. Usually it means you should turn your solar system off around the time the meter is being read. If you sign up for the PEA program then all is fine but your break even will be maybe in 8-9 years. Still a worthwhile thing to do. Grid-tie means btw that when the grid is down then your solar system is also down as it needs to sync with the frequency of the grid. With grid-tie you don't need any switching between solar and grid. Forget also off-grid without batteries, your solar generation will be way too inconsistent to run your house hassle-free.

Edited by eisfeld
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8 hours ago, BritManToo said:

Assume you will get between between 1/2-1 unit a day per 330w solar panel (2m x 1m).

(I get 1/2 but another poster thinks he get 1)

Then work out how many units you use a day to calculate the number of panels you need.

Panels cost 4k, grid tie inverter cost 4k and can take 2 panels.

You can buy more expensive GTIs, but the costs remain fairly constant.

Do not use those shitty micro inverters and you should see more than 1 unit per day from a 330W panel. I have data from two installs in Phuket that are around the 7kW mark and do more than 1 unit per day as well. Best month was march where the system generated 972kWh which broken down to 330W panels would be more than 1.5 units per panel. June was the lowest this year with 736kWh which would be still more than 1.16kWh per 330W. Since panel sizes vary much I wouldn't recommend in thinking in 330W panels. Better to think in kWh (or units) generated per kW. You can estimate roughly 1400kWh per year per kW or something like 120 units per kW per month.

 

0.5kWh per 330W per day would mean about 550 kWh per year per kW which is very very poor.

BTW the micro inverter you posted in the other thread had only 1 input as far as I could see and 2 panels might provide too much voltage for it since you'd need to put them in series which would easily generate 60+V and I saw in the specs of it a very narrow voltage range of 30-40V.

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Posted (edited)
2 hours ago, Stevey said:

Electric oven ?? 😂😂😂😂😂

Your problem is? I already have an oven in my current home at Khao Yai. I don't use the oven much but I use the grill in it almost every day that I'm there. I wouldn't be without the oven, I'm not too good at learning other methods of cooking - I guess I'm set in my ways. Its there when I need it. If you find that funny, I'm pleased to have entertained you.

 

Yes, I'm a westerner, I don't sit cross legged on the floor and nor do I prepare my food there either. I don't make merit or go to the temple. Are you any different?

 

I'm clearly not the only person with an oven - the shop in Korat where I bought it has quite a few in stock. Thai's don't stock things that don't sell.

Edited by KhaoYai

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I should have made it clear from the outset, I have no intention of only having solar power.

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