Solar Power

[IMHO]

I was talking about deep cycle batteries in my quote.

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

Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates.

I do understand

See if you can find an actual spec sheet for an actual model you're interested in that shows the relationship of DOD vs. cyclic life though - sure they *can* do it - SLA can even do 100% DOD, but not for many cycles.

[Anthony5]

I was talking about deep cycle batteries in my quote.

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

Deep cycle batteries are designed to be discharged down as much as 80% time after time, and have much thicker plates.

I do understand

See if you can find an actual spec sheet for an actual model you're interested in that shows the relationship of DOD vs. cyclic life though - sure they *can* do it - SLA can even do 100% DOD, but not for many cycles.

Lifepo4 batteries are far superior compared to lead acid batteries, but if you go on the Australian solar forums, you will find that they aren't used because price wise they are not viable for the the extra DOD and life cycles they provide.

Lifepo4 batteries also have an extremely low self discharge and are easy to store. A battery stored for a year will have discharged almost nothing. At the same time they keep the same discharge capacity under load until they are completely discharged.

Keep in mind that the batteries offered on Ebay and Chinese sites will have a questionable quality. If you look at a quality Lifepo4 you will also look at a multiple of those prices.

[ExpatOilWorker]

The ultimate battery solution would be a Vanadium flow (http://en.wikipedia.org/wiki/Vanadium_redox_battery), that supposedly have unlimited cycles.

There is a company is Thailand that produce Vanadium batteries (http://vanadiumbattery.com/index.php/welcome/index).

From Google the average price is around $1,000/kWh, so it will add about $12,000 to a household sized system.

[IMHO]

The ultimate battery solution would be a Vanadium flow (http://en.wikipedia.org/wiki/Vanadium_redox_battery), that supposedly have unlimited cycles.

There is a company is Thailand that produce Vanadium batteries (http://vanadiumbattery.com/index.php/welcome/index).

From Google the average price is around $1,000/kWh, so it will add about $12,000 to a household sized system.

My house would need at least 100kWh usable to go fully off-grid (avg daily usage of up to 50 units, with 2 days of autonomy for cloudy days etc). Interesting tech though, and while initial outlay is expensive, if they could last 15 years or more, they might work out.

Thanks for the links

[ExpatOilWorker]

The ultimate battery solution would be a Vanadium flow (http://en.wikipedia.org/wiki/Vanadium_redox_battery), that supposedly have unlimited cycles.

There is a company is Thailand that produce Vanadium batteries (http://vanadiumbattery.com/index.php/welcome/index).

From Google the average price is around $1,000/kWh, so it will add about $12,000 to a household sized system.

My house would need at least 100kWh usable to go fully off-grid (avg daily usage of up to 50 units, with 2 days of autonomy for cloudy days etc). Interesting tech though, and while initial outlay is expensive, if they could last 15 years or more, they might work out.

Thanks for the links

Once you go solar, I think you by default eliminate the electric water heater, use low energy light bulbs and maybe even get a gas stove. Even on a cloudy day solar panels should produce a few kWh, you could dip deeper into your normal day/night battery cycles and skip doing heavy load activities as the Sunday roast in the oven, use vacuum cleaner, tumble dryer, etc.

1 rainy day only need to cover 36 hours battery time.

All in all 40-50 kWh of storage capacity could probably cover 50 kWh/day normal usage during 1 or 2 cloudy days.

[khunPer]

I just today saw a new Danish calculation of investment in Solar Cell electric – very popular in Northern Europe, but partly based on tax exemption – perhaps partial convertible...

The sample used is a 5kW installation based on 5,000kWh annual production (may be higher in Thailand), and a yearly effect decrease in solar cells of 0.5%. The installation cost is close to 400,000 thb (may be lower here) and the pay back price per kWh hour equivalent to little more than 5 thb (may likely be around 4 thb if meter runs backwards here). Furthermore an annual price increase on 2.8% per kWh is included in the calculations.

With 40% own consumption and no loan, the payback time is calculated to about 16 years, and with a 5% loan to ca. 20 years.

It shall be noted, that “own consumption” may be based on equivalent to a buying price of around 10 thb and up per kWh, whilst in Thailand you rather pay between 4 and 5 thb per kWh.

If you use less than 40% yourself and borrow money for installation, the pay back time can exceed 30 years.

The source, which is a very comprehensive article by Danish government organization Energy Service in the newspaper Jyllands-Posten, is unfortunately is in Danish language.

OK, now halve the price of the system - a 5kW grid tie is only going to cost 200K Baht installed here, and then give it almost double the kWh per sqm by installing it in Thailand, and I think you'll find it's pretty close to my 7 year payback calcs (no sell meter) or 4 years (with sell meter)

(Images deleted)

But I agree - it's highly unlikely I would consider doing rooftop solar in Denmark

Thanks for your reply IMHO.

Actually there are lots of solar cell installation in Denmark and neighboring countries; you need to take into consideration the extreme long days in the summer time. Some of my friends back home have solar cell installation and claim they make money...

The Danish Engineer Society published an article yesterday about the upcoming problem with the solar eclipse over the North Atlantic (full eclipse over Faroe Islands) March 20, and the effect on the European grid, where a capacity equivalent of 150 to 200 middle sized power stations will disappear within minutes. The Danish solar electric production are said to be 600MW (equivalent to 1½ to 2 big power stations), whilst the total Northern European solar power production is stated to 90GW, being reduced with around 35GW during the eclipse.

So that’s another problem to cope with, but happens only rarely.

But agree with you, that the prospects for installing solar cell in Thailand is much better now, than when I was planning and building my house some 6 years ago, and estimated around 17-18 years payback time, and therefore not really worth the investment as perhaps the equipment would not live that long time in Thailand; seems like weather etc. makes most equipment "live hard and and die young".

[IMHO]

The ultimate battery solution would be a Vanadium flow (http://en.wikipedia.org/wiki/Vanadium_redox_battery), that supposedly have unlimited cycles.

There is a company is Thailand that produce Vanadium batteries (http://vanadiumbattery.com/index.php/welcome/index).

From Google the average price is around $1,000/kWh, so it will add about $12,000 to a household sized system.

My house would need at least 100kWh usable to go fully off-grid (avg daily usage of up to 50 units, with 2 days of autonomy for cloudy days etc). Interesting tech though, and while initial outlay is expensive, if they could last 15 years or more, they might work out.

Thanks for the links

Once you go solar, I think you by default eliminate the electric water heater, use low energy light bulbs and maybe even get a gas stove. Even on a cloudy day solar panels should produce a few kWh, you could dip deeper into your normal day/night battery cycles and skip doing heavy load activities as the Sunday roast in the oven, use vacuum cleaner, tumble dryer, etc.

1 rainy day only need to cover 36 hours battery time.

All in all 40-50 kWh of storage capacity could probably cover 50 kWh/day normal usage during 1 or 2 cloudy days.

Agreed. We have 2x solar hot water heaters (150L & 200L - both of which have disconnected 1500W heating elements - solar only), all cooktops in our 3 kitchens are gas, most commonly used ~80 lights are all LED with a max of 7W (others are CFL). But we still get high usage because of our 3 fridges, 1 freezer, 500W TV, Electric oven, Microwave and 3/8 AC's that see 10 hours/day use

We're just big users

[khunPer]

The ultimate battery solution would be a Vanadium flow (http://en.wikipedia.org/wiki/Vanadium_redox_battery), that supposedly have unlimited cycles.

There is a company is Thailand that produce Vanadium batteries (http://vanadiumbattery.com/index.php/welcome/index).

From Google the average price is around $1,000/kWh, so it will add about $12,000 to a household sized system.

My house would need at least 100kWh usable to go fully off-grid (avg daily usage of up to 50 units, with 2 days of autonomy for cloudy days etc). Interesting tech though, and while initial outlay is expensive, if they could last 15 years or more, they might work out.

Thanks for the links

Once you go solar, I think you by default eliminate the electric water heater, use low energy light bulbs and maybe even get a gas stove. Even on a cloudy day solar panels should produce a few kWh, you could dip deeper into your normal day/night battery cycles and skip doing heavy load activities as the Sunday roast in the oven, use vacuum cleaner, tumble dryer, etc.

1 rainy day only need to cover 36 hours battery time.

All in all 40-50 kWh of storage capacity could probably cover 50 kWh/day normal usage during 1 or 2 cloudy days.

Agreed. We have 2x solar hot water heaters (150L & 200L - both of which have disconnected 1500W heating elements - solar only), all cooktops in our 3 kitchens are gas, most commonly used ~80 lights are all LED with a max of 7W (others are CFL). But we still get high usage because of our 3 fridges, 1 freezer, 500W TV, Electric oven, Microwave and 3/8 AC's that see 10 hours/day use

We're just big users

Solar water heater seems to make good sense, especially in Thailand. I installed that when building, with a 200-liter tank (it even got an electric build-in heater, which has not been connected). The total cost at that time, about 6 years ago, was around 40,000 baht. Works fine, in sunny days almost boiling water, and even without a detailed calculation as proof, I do believe that kind of solar-power-investment makes sense. I have small instant water heaters in the bathrooms to boost hot water, in case of days without sun, or not enough sun.

LED bulbs are also a good investment, if you buy quality bulbs (or brand names) ; some of the cheap Chinese stuff coming on the market here in the beginning did not last “the promised” up to 20 years, some makes lasted up to 20 minutes or 20 hours only.

[ExpatOilWorker]

Assuming the ACs use 25 kWh day, the aircon usage could be eliminated from the battery equation, by having a water heat sink. 10 m3 would cover a full 24 hour cycle with only a 10 degree C temperature increase of the heat sink. Probably longer, since it is safe to assume less aircon is required during cloudy days.

I once visited an ice factory and they used 1 million baht of electricity every month. Solar would be ideal for them, just produce all the ice during day time and shut down for the night.

[IMHO]

Assuming the ACs use 25 kWh day, the aircon usage could be eliminated from the battery equation, by having a water heat sink. 10 m3 would cover a full 24 hour cycle with only a 10 degree C temperature increase of the heat sink. Probably longer, since it is safe to assume less aircon is required during cloudy days.

I once visited an ice factory and they used 1 million baht of electricity every month. Solar would be ideal for them, just produce all the ice during day time and shut down for the night.

I think the main point for me is, the only viable option ATM is grid-tie - off grid just doesn't work out (yet). Nothing particularly wrong with that though, while our supply mains voltage is crap under load, it rarely drops out.

[Forkinhades]

Yeah for me it would be grid tie. I would also use UPS with autonomy of 4 hours for power outages, on essential circuits.

[IMHO]

Yeah for me it would be grid tie. I would also use UPS with autonomy of 4 hours for power outages, on essential circuits.

Yep, I have been researching hybrid grid-tie inverter options for this reason. Something that could keep my 4 fridges/freezer, water pump, and some essential lights running for a few hours would do. So far though, it seems easier/cheaper/more effecient just to use a standard UPS (i.e. mains charged).

[ExpatOilWorker]

It is interesting to see that the Chinese solar panels have not changed much in price the German and Japanese panels have come down in price the past 2 years. Once Greece tear the Euro apart, we might start to see some quality German solar panels out here.

With wholesale prices at $0.60/W, it is impressive the retail price is only $0.92/W in Thailand.

http://www.solarserver.com/service/pvx-spot-market-price-index-solar-pv-modules.html?gclid=CjwKEAiAveWnBRCzjqf4zpuUkGYSJABcoZbHdBZr7Bqv9Mo_fmOD7tlS-Eia9C5Nh0tOtbzpm2jG3xoCKf3w_wcB

[khunPer]

Yeah for me it would be grid tie. I would also use UPS with autonomy of 4 hours for power outages, on essential circuits.

Grid stability, or rather lack of same, is a very good reason to consider backup from Solar Energy. Just backup from UPS is essential in many cases to get stability and eliminate (very) short power cuts or voltage drops appearing in many areas. As poster Arjen says in #72, not a questions of saving money, but independency from unreliable grid.

However, the small UPS around 400-500 Watt that you can buy for computers and other sensitive electronics, can often help a lot for an investment of around 2,000 baht each; but will not work for all machinery. I use for example a standard UPS for an extra light circuit – as I live in an area famous for power cuts – so we always have some light in bathrooms, stairs and kitchen for some hours; I replaced the build-in battery with a larger external, which is easy to change when worn out (they only live 2-3 years in areas with power cuts), that gives some 4 to 7 hours light in urgent rooms (we, the island I live, have tried a 3-day power cut, that’s not fun).

[Forkinhades]

^ yes indeed sir, but I was not talking about ups with automony of 15 minutes for computers. You should be looking at bigger UPS systems, which invariably might mean building one yourself.

[khunPer]

^ yes indeed sir, but I was not talking about ups with automony of 15 minutes for computers. You should be looking at bigger UPS systems, which invariably might mean building one yourself.

Sure, that will be preferable ; but even a number of smaller easily available UPS can help a lot, and with less usage than nominated power, and an extended battery storage – for example for light during a power break – you can have several hours of backup for a (very) small investment.

My post was just a remark to those who might be interested for some backup at affordable cost – it designed the power-system in my house with several individual circuits using small commercial UPS, work well, and can easily be combined to a single larger system that may be solar powered instead of charging batteries from main, when that solar cell investment pays off.

[IMHO]

@Anthony5: Some interesting real-world info on LifePo4's here: http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/

Seems there's going to be some real challenges to realize their benefits in a climate like ours.

[Anthony5]

@Anthony5: Some interesting real-world info on LifePo4's here: http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/

Seems there's going to be some real challenges to realize their benefits in a climate like ours.

Indeed an interesting read.

The degrading with temperature is something lead acid batteries also suffer, and while at the end of the test period he had only 75% of their rated capacity left, that is still more than a lead acid battery.

I suspect his biggest problem is that he didn't make use a balance charger. A lifepo4 battery needs a special designated charger.

Maybe when Tesla builds that huge battery factory in joint venture with Panasonic I think, prices may come down and make it more affordable.

[IMHO]

@Anthony5: Some interesting real-world info on LifePo4's here: http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/

Seems there's going to be some real challenges to realize their benefits in a climate like ours.

Indeed an interesting read.

The degrading with temperature is something lead acid batteries also suffer, and while at the end of the test period he had only 75% of their rated capacity left, that is still more than a lead acid battery.

I suspect his biggest problem is that he didn't make use a balance charger. A lifepo4 battery needs a special designated charger.

Maybe when Tesla builds that huge battery factory in joint venture with Panasonic I think, prices may come down and make it more affordable.

Yep, for now, I think anyone doing a UPS or off-grid should just save their money and buy lead acid - by the time they need to be replaced, it will be a totally different landscape.

[Anthony5]

Life time from my Lead-Acid was usually less then a year.

Now I bought Deep-Cycle batteries (finally available) Also Lead-Acid. Price was only 140.000 Baht for 2.000Ah.

Now see how long the life time is.....

Arjen.

140.000 Baht for 2000Ah? Someone must have had a party .

Below is the price from deep cycle batteries as they were offered to me.

NC EB100 (12V 100Ah/5HR, 125Ah/20HR) @ Bht. 4,350.00

NC EB160 (12V 160Ah/5HR, 200Ah/20HR) @ Bht. 6,400.00

3K EBB100 (12V 100Ah/20HR) @ Bht. 4,660.00

3K EBB125 (12V 125Ah/20HR) @ Bht. 5,050.00

3K EB130 (12V 160Ah/5HR) @ Bht. 6,600.00

[IMHO]

Life time from my Lead-Acid was usually less then a year.

Now I bought Deep-Cycle batteries (finally available) Also Lead-Acid. Price was only 140.000 Baht for 2.000Ah.

Now see how long the life time is.....

Arjen.

140.000 Baht for 2000Ah? Someone must have had a party .

Below is the price from deep cycle batteries as they were offered to me.

NC EB100 (12V 100Ah/5HR, 125Ah/20HR) @ Bht. 4,350.00

NC EB160 (12V 160Ah/5HR, 200Ah/20HR) @ Bht. 6,400.00

3K EBB100 (12V 100Ah/20HR) @ Bht. 4,660.00

3K EBB125 (12V 125Ah/20HR) @ Bht. 5,050.00

3K EB130 (12V 160Ah/5HR) @ Bht. 6,600.00

He didn't specify what voltage though

That's why I always talk in Wh for batteries

[Naam]

Monthly electric bill 600-900baht depending season/months.

I wonder how long you plan to live and 36 hours a day aircon

That's a pretty low bill... we average exactly 10x that

four months last year (may-august 2014) we had an average of 673 Baht a day

[Naam]

@Anthony5: Some interesting real-world info on LifePo4's here: http://www.technomadia.com/2015/02/living-the-lithium-lifestyle-3-5-year-lithium-rv-battery-update/

Seems there's going to be some real challenges to realize their benefits in a climate like ours.

Indeed an interesting read.

The degrading with temperature is something lead acid batteries also suffer, and while at the end of the test period he had only 75% of their rated capacity left, that is still more than a lead acid battery.

I suspect his biggest problem is that he didn't make use a balance charger. A lifepo4 battery needs a special designated charger.

Maybe when Tesla builds that huge battery factory in joint venture with Panasonic I think, prices may come down and make it more affordable.

Yep, for now, I think anyone doing a UPS or off-grid should just save their money and buy lead acid - by the time they need to be replaced, it will be a totally different landscape.

i am using lead acid (4 systems each 2x12V -2x120 Ah) average life span 4½-5 years (experience based on 10 year operation).

cost each 3,700 Baht minus 300 Baht refund for old battery.

[Forkinhades]

Are they for your UPS systems? In which case would not be discharging every day?

[Forkinhades]

^ that makes it clear why your lead acid batteries are failing after 12 months

[Crossy]

@arjen.

Since you are using up batteries inside 12 months have you done a cost-benefit analysis of running off the grid during the hours of darkness, or running your batteries less hard, maybe to 25% discharge only before switching to grid power?

Even with grid power being unstable it could still be cheaper than replacing the batteries every year.

You can still use the system as a giant UPS for when the grid goes outside of your tolerable range at which point you can use more of the battery capacity.

[Forkinhades]

^ +1 Xy

[Crossy]

With a PLC / computer running the whole shooting match and suitable sensors the world is your oyster. I'm sure many of us would be interested in your semi-off grid lifestyle and the kit you use to attain it.

Perhaps add in a small (500W or so) grid-tie inverter to "top-up" the meter (spin it backwards until it's in the "zero bill" zone) when usage is low but the sun is bright

This is exactly the sort of thing I like to consider, unfortunately (?) our grid supply is pretty reliable so the costs of trying to go pure solar outweigh any green advantages (as yet of course).

[IMHO]

Probably I wrote wrong. I use them to store electricity produced by my solar panels. I produce at day time more then I use. At night I am running our house on the electricity stored in those batteries.

I said "designed as a huge UPS" because I do not have a grid-tied inverter. I started using this set-up, because our mains supply is very unstable. After extending the installation several times it is big enough to run 24 hours/day, 7 days/week my own electricity. Only when we have bad weather, or it is extreme hot (panels produce then less) I need the grid. And for welding and some other tools I rely on the grid. So my batteries are every night discharged.

Regards, Arjen.

If you're only getting 365 cycles (days) out of lead acid, the only logical explanation is that your battery pack is undersized. As a basic rule of thumb, lead acid should never be discharged more than 50% in cyclic use. Most solar off-grid systems using lead acid target for 20-30% depth of discharge only, in order to maximize battery cyclic life.

[IMHO]

@IMHO and @Crossy,

Thanks for the info.

I do not want to install an other inverter, but I will set the PLC so that I do not discharge the batteries for more then 25% Per direct I will use my solar energy only when I am not home and at night. This will keep the batteries continuous fully charged, and protects enough against failure from our grid.

I always used normal car batteries, I know they are not suitable for this application, but did not have much choice. Life time was more closer to three months. First time I even had 4.000Ah.

Now I have a maximum current from the panels from around 60A, at 24V So charge current to batteries is maximum 6A. Discharge current can be around 12A. I do not dare to say what is the average production in 24 Hour. But when the PLC is running I can tell this. I also want to measure the production from the panels, from the charger to batteries, from batteries to inverter, and from inverter to my 220V installation. I think I may be happy when finally 50% is effective used. When I should design the system again I should use much more 24V lighting systems.

And as you may notice, I do not have any electrical background, i am just very much interested in this stuff.

Regards, Arjen.

One more thing that might be impacting your battery life is the way it's wired... Yep, it all seems pretty simple to do series and parallel wiring, but there's more to it than meets the eye.

Essential reading on battery bank wiring here: http://www.smartgauge.co.uk/batt_con.html

Also,. here's a good read about lead acid voltage and depth of discharge, for your PLC: http://www.scubaengineer.com/documents/lead_acid_battery_charging_graphs.pdf