Posted by Curbie on April 10, 2011, 9:24 pm
wrote:
>On 4/7/2011 7:28 AM, sno wrote:
>> On 4/7/2011 8:01 AM, Tom P wrote:
>>> On 04/07/2011 02:48 PM, Giga2 <Giga2 wrote:
>>>>> On 04/07/2011 10:22 AM, Giga2<Giga2 wrote:
>>>>>>> On 04/06/2011 11:33 PM, John wrote:
>>>>>>>>> On 04/06/2011 05:14 PM, Vaughn wrote:
>>>>>>>>>> wrote
>>>>>>>>>> in
>>>>>>>>>>> After all its pretty much a solid-state component with no moving
>>>>>>>>>>> parts
>>>>>>>>>> "Pretty much" yes, but it's the exceptions that kill you. Most
>>>>>>>>>> inverters
>>>>>>>>>> incorporate both fans and electrolytic capacitors. Neither of
>>>>>>>>>> those
>>>>>>>>>> items
>>>>>>>>>> last forever, either will cause failure.
>>>>>>>>>>
>>>>>>>>>>> I can't see any particular reason they wouldn't last for 50 years
>>>>>>>>>>
>>>>>>>>>> 50 years is wildly optimistic. There are too many things that can
>>>>>>>>>> happen
>>>>>>>>>> to
>>>>>>>>>> any installation. Some of them have little or nothing to do with
>>>>>>>>>> the
>>>>>>>>>> robustness of the design. Equipment can get zapped by line
>>>>>>>>>> surges or
>>>>>>>>>> lightning, can get wet, stolen, attacked by bugs or rodents,
>>>>>>>>>> displaced
>>>>>>>>>> by
>>>>>>>>>> home repairs& renovations; the list goes on...
>>>>>>>>>>
>>>>>>>>>> Vaughn
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> Then there's the question whether the roof it's mounted on will
>>>>>>>>> last
>>>>>>>>> 50
>>>>>>>>> years. It's written off after 20 years anyway. How much do you
>>>>>>>>> worry
>>>>>>>>> whether your new car will last 20 years or 50 years?
>>>>>>>>
>>>>>>>> This is interesting. Whereabouts in central Europe are you located
>>>>>>>> Tom.
>>>>>>>> How much sun relative to say the south UK?
>>>>>>>>
>>>>>>>>
>>>>>>> About the same latitude - Germany.
>>>>>>>
>>>>>>
>>>>>> To be fair latitude isn't the only factor here. Cloudiness is also
>>>>>> important. I lived in Germany and summers were much longer and
>>>>>> warmer and
>>>>>> even winters were brighter (tho colder) in general.
>>>>>>
>>>>>>
>>>>> There are some figures here -
>>>>> http://www.climatedata.eu/continent.php?cid 0&lang=en
>>>>>
>>>>> The south coast of England is even sunnier, despite all rumours to the
>>>>> contrary.
>>>>>
>>>>>
>>>> Shocking! Do you know why concentrated solar, using lenses to
>>>> intensify the
>>>> light, isn't being used yet? Surely you *could* make these panels 10x
>>>> more
>>>> efficient just by incresing their collection area by 10x for the same
>>>> silicon!? Just print a sheet of lenses the same size and at the focus of
>>>> each a small 'panel' a tenth the size of the current silicon.
>>>>
>>>>
>>> I have heard of such a technology - a sheet of plastic embedded with
>>> "fly's eye" lenses covering the matrix carrying the PV cells. The idea
>>> is that the smaller PV cells at the focus point can use a more expensive
>>> but more advanced technology.
>>> I don't know what the official brand name is, if any. The disadvantage
>>> is that the panel needs to be steerable to be effective, and you will
>>> still need the same area as a normal PV panel. As the current conversion
>>> efficiency is around 10-15%, you would need super performance cells of
>>> 100% efficiency to justify a 10:1 magnification.
>>
>> I have heard that concentrating the sun like this can cause the cells to
>> heat up....greatly reducing their efficiency....I do not imagine one or
>> two sun power increases would cause much heating...
>No, actually the most efficient cells operate at 300-400 suns.
Peter,
Can you cite this 300-400 sun claim???
These "most efficient cells" can dissipate the heat???
Correct me if I'm wrong, at 1 kWh/m2 (or 317 btu/ft2) doesn't a PV
cell convert <20% of solar energy to electricity and >80% to heat???
Rough math:
1000 (Wh/m2) * .80 (%) = 800(Wh/m2) or 254 (btu/ft2) of heat to
dissipate at 1 sun and 280 (kWh/m2) or 88 (kbtu/ft2) at 350 suns,
seems like an awful lot heat to dissipate.
NREL's PV-watts starts reducing the efficiency of PV cells at 45C
(113F).
Curbie
Posted by Malcom \"Mal\" Reynolds on April 11, 2011, 5:13 am
> Peter,
>
> Can you cite this 300-400 sun claim???
>
> These "most efficient cells" can dissipate the heat???
>
> Correct me if I'm wrong, at 1 kWh/m2 (or 317 btu/ft2) doesn't a PV
> cell convert <20% of solar energy to electricity and >80% to heat???
> Rough math:
>
> 1000 (Wh/m2) * .80 (%) = 800(Wh/m2) or 254 (btu/ft2) of heat to
> dissipate at 1 sun and 280 (kWh/m2) or 88 (kbtu/ft2) at 350 suns,
> seems like an awful lot heat to dissipate.
>
> NREL's PV-watts starts reducing the efficiency of PV cells at 45C
> (113F).
>
> Curbie
Of course that is an awful lot of potentially valuable heat that could be
collected and used for other purposes. I'd imagine it could even power an Air
Conditioner
Posted by Giga2 on April 7, 2011, 7:00 pm
> On 04/07/2011 02:48 PM, Giga2 <Giga2 wrote:
>>> On 04/07/2011 10:22 AM, Giga2<Giga2 wrote:
>>>>> On 04/06/2011 11:33 PM, John wrote:
>>>>>>> On 04/06/2011 05:14 PM, Vaughn wrote:
>>>>>>>> wrote
>>>>>>>> in
>>>>>>>>> After all its pretty much a solid-state component with no moving
>>>>>>>>> parts
>>>>>>>> "Pretty much" yes, but it's the exceptions that kill you. Most
>>>>>>>> inverters
>>>>>>>> incorporate both fans and electrolytic capacitors. Neither of
>>>>>>>> those
>>>>>>>> items
>>>>>>>> last forever, either will cause failure.
>>>>>>>>
>>>>>>>>> I can't see any particular reason they wouldn't last for 50 years
>>>>>>>>
>>>>>>>> 50 years is wildly optimistic. There are too many things that can
>>>>>>>> happen
>>>>>>>> to
>>>>>>>> any installation. Some of them have little or nothing to do with
>>>>>>>> the
>>>>>>>> robustness of the design. Equipment can get zapped by line surges
>>>>>>>> or
>>>>>>>> lightning, can get wet, stolen, attacked by bugs or rodents,
>>>>>>>> displaced
>>>>>>>> by
>>>>>>>> home repairs& renovations; the list goes on...
>>>>>>>>
>>>>>>>> Vaughn
>>>>>>>>
>>>>>>>>
>>>>>>> Then there's the question whether the roof it's mounted on will
>>>>>>> last
>>>>>>> 50
>>>>>>> years. It's written off after 20 years anyway. How much do you worry
>>>>>>> whether your new car will last 20 years or 50 years?
>>>>>>
>>>>>> This is interesting. Whereabouts in central Europe are you located
>>>>>> Tom.
>>>>>> How much sun relative to say the south UK?
>>>>>>
>>>>>>
>>>>> About the same latitude - Germany.
>>>>>
>>>>
>>>> To be fair latitude isn't the only factor here. Cloudiness is also
>>>> important. I lived in Germany and summers were much longer and warmer
>>>> and
>>>> even winters were brighter (tho colder) in general.
>>>>
>>>>
>>> There are some figures here -
>>> http://www.climatedata.eu/continent.php?cid 0&lang=en
>>>
>>> The south coast of England is even sunnier, despite all rumours to the
>>> contrary.
>>>
>>>
>> Shocking! Do you know why concentrated solar, using lenses to intensify
>> the
>> light, isn't being used yet? Surely you *could* make these panels 10x
>> more
>> efficient just by incresing their collection area by 10x for the same
>> silicon!? Just print a sheet of lenses the same size and at the focus of
>> each a small 'panel' a tenth the size of the current silicon.
>>
>>
> I have heard of such a technology - a sheet of plastic embedded with
> "fly's eye" lenses covering the matrix carrying the PV cells. The idea is
> that the smaller PV cells at the focus point can use a more expensive but
> more advanced technology.
> I don't know what the official brand name is, if any. The disadvantage
> is that the panel needs to be steerable to be effective, and you will
> still need the same area as a normal PV panel. As the current conversion
> efficiency is around 10-15%, you would need super performance cells of
> 100% efficiency to justify a 10:1 magnification.
OK, seems like it should work tho!
Posted by Giga2 on April 7, 2011, 8:20 am
> On 04/06/2011 05:14 PM, Vaughn wrote:
>> in
>>> After all its pretty much a solid-state component with no moving parts
>> "Pretty much" yes, but it's the exceptions that kill you. Most inverters
>> incorporate both fans and electrolytic capacitors. Neither of those
>> items
>> last forever, either will cause failure.
>>
>>> I can't see any particular reason they wouldn't last for 50 years
>>
>> 50 years is wildly optimistic. There are too many things that can happen
>> to
>> any installation. Some of them have little or nothing to do with the
>> robustness of the design. Equipment can get zapped by line surges or
>> lightning, can get wet, stolen, attacked by bugs or rodents, displaced by
>> home repairs& renovations; the list goes on...
>>
>> Vaughn
>>
>>
> Then there's the question whether the roof it's mounted on will last 50
> years. It's written off after 20 years anyway. How much do you worry
> whether your new car will last 20 years or 50 years?
Even if the roof needs replacing it would be easy enough to remove the
panels, refurbish them (probably just give them a good clean and new
contacts) and put them back up afterwards. And they will protect the roof
presumably.
Posted by Giga2 on April 7, 2011, 8:18 am
>> After all its pretty much a solid-state component with no moving parts
> "Pretty much" yes, but it's the exceptions that kill you. Most inverters
> incorporate both fans and electrolytic capacitors. Neither of those items
> last forever, either will cause failure.
>> I can't see any particular reason they wouldn't last for 50 years
> 50 years is wildly optimistic. There are too many things that can happen
> to any installation. Some of them have little or nothing to do with the
> robustness of the design. Equipment can get zapped by line surges or
> lightning, can get wet, stolen, attacked by bugs or rodents, displaced by
> home repairs & renovations; the list goes on...
Sure but the actual devices in themselves seem like they should be very
robust.
>
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>> On 4/7/2011 8:01 AM, Tom P wrote:
>>> On 04/07/2011 02:48 PM, Giga2 <Giga2 wrote:
>>>>> On 04/07/2011 10:22 AM, Giga2<Giga2 wrote:
>>>>>>> On 04/06/2011 11:33 PM, John wrote:
>>>>>>>>> On 04/06/2011 05:14 PM, Vaughn wrote:
>>>>>>>>>> wrote
>>>>>>>>>> in
>>>>>>>>>>> After all its pretty much a solid-state component with no moving
>>>>>>>>>>> parts
>>>>>>>>>> "Pretty much" yes, but it's the exceptions that kill you. Most
>>>>>>>>>> inverters
>>>>>>>>>> incorporate both fans and electrolytic capacitors. Neither of
>>>>>>>>>> those
>>>>>>>>>> items
>>>>>>>>>> last forever, either will cause failure.
>>>>>>>>>>
>>>>>>>>>>> I can't see any particular reason they wouldn't last for 50 years
>>>>>>>>>>
>>>>>>>>>> 50 years is wildly optimistic. There are too many things that can
>>>>>>>>>> happen
>>>>>>>>>> to
>>>>>>>>>> any installation. Some of them have little or nothing to do with
>>>>>>>>>> the
>>>>>>>>>> robustness of the design. Equipment can get zapped by line
>>>>>>>>>> surges or
>>>>>>>>>> lightning, can get wet, stolen, attacked by bugs or rodents,
>>>>>>>>>> displaced
>>>>>>>>>> by
>>>>>>>>>> home repairs& renovations; the list goes on...
>>>>>>>>>>
>>>>>>>>>> Vaughn
>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>> Then there's the question whether the roof it's mounted on will
>>>>>>>>> last
>>>>>>>>> 50
>>>>>>>>> years. It's written off after 20 years anyway. How much do you
>>>>>>>>> worry
>>>>>>>>> whether your new car will last 20 years or 50 years?
>>>>>>>>
>>>>>>>> This is interesting. Whereabouts in central Europe are you located
>>>>>>>> Tom.
>>>>>>>> How much sun relative to say the south UK?
>>>>>>>>
>>>>>>>>
>>>>>>> About the same latitude - Germany.
>>>>>>>
>>>>>>
>>>>>> To be fair latitude isn't the only factor here. Cloudiness is also
>>>>>> important. I lived in Germany and summers were much longer and
>>>>>> warmer and
>>>>>> even winters were brighter (tho colder) in general.
>>>>>>
>>>>>>
>>>>> There are some figures here -
>>>>> http://www.climatedata.eu/continent.php?cid 0&lang=en
>>>>>
>>>>> The south coast of England is even sunnier, despite all rumours to the
>>>>> contrary.
>>>>>
>>>>>
>>>> Shocking! Do you know why concentrated solar, using lenses to
>>>> intensify the
>>>> light, isn't being used yet? Surely you *could* make these panels 10x
>>>> more
>>>> efficient just by incresing their collection area by 10x for the same
>>>> silicon!? Just print a sheet of lenses the same size and at the focus of
>>>> each a small 'panel' a tenth the size of the current silicon.
>>>>
>>>>
>>> I have heard of such a technology - a sheet of plastic embedded with
>>> "fly's eye" lenses covering the matrix carrying the PV cells. The idea
>>> is that the smaller PV cells at the focus point can use a more expensive
>>> but more advanced technology.
>>> I don't know what the official brand name is, if any. The disadvantage
>>> is that the panel needs to be steerable to be effective, and you will
>>> still need the same area as a normal PV panel. As the current conversion
>>> efficiency is around 10-15%, you would need super performance cells of
>>> 100% efficiency to justify a 10:1 magnification.
>>
>> I have heard that concentrating the sun like this can cause the cells to
>> heat up....greatly reducing their efficiency....I do not imagine one or
>> two sun power increases would cause much heating...
>No, actually the most efficient cells operate at 300-400 suns.
Peter,