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Solar Panel Guide Discussion
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Sirlaughalot wrote: »Thanks for that Mart,
Just had some great news from one firm who quoted earlier. He reckons the first company to quote got it wrong with the roof measurements.
Its now 7.1m x 5.3m which with a bit of tinkering with portrait/landscape variants will allow 16 x 250 KW panels
SL
Hiya SL, flying visit. Can you get into the loft and measure it from the inside. It'll be a close enough measure, and the inside will roughly equate to the useable outside area, since you need to leave gaps on the side for wind lift (I think), and the top for planning permission, so the panels aren't higher than the ridge, and the bottom, again for fixings and wind lift.Sirlaughalot wrote: »16 x 250 KW panels and he reckons with a software update on the inverter the whole system should over perform and pump out 4300/4400 KW! Are there any pitfalls to this software update ie warranty issues or safety concerns
SL
Way out of my depth here, hopefully Roger or Zeup can comment, but this doesn't sound right to me. If the power is 16 * 250Wp, then that's what the inverter has to work with. A better inverter will be more efficient, but you are probably looking at 95%+ anyway. In fact a good inverter might be 96 to 98%, so there is very little room for improvement - the inverter can't create extra power, so unless your set up and location can send 4,300+kWh's to the inverter, there's no way it can come out the other end, even at 100% efficiency(?)
I'll look forward to a lesson from the clever guys. Hopefully they'll be along soon.
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: »Hiya SL, flying visit. Can you get into the loft and measure it from the inside. It'll be a close enough measure, and the inside will roughly equate to the useable outside area, since you need to leave gaps on the side for wind lift (I think), and the top for planning permission, so the panels aren't higher than the ridge, and the bottom, again for fixings and wind lift.
Way out of my depth here, hopefully Roger or Zeup can comment, but this doesn't sound right to me. If the power is 16 * 250Wp, then that's what the inverter has to work with. A better inverter will be more efficient, but you are probably looking at 95%+ anyway. In fact a good inverter might be 96 to 98%, so there is very little room for improvement - the inverter can't create extra power, so unless your set up and location can send 4,300+kWh's to the inverter, there's no way it can come out the other end, even at 100% efficiency(?)
I'll look forward to a lesson from the clever guys. Hopefully they'll be along soon.
Mart.
Bit baffled me self to be honest just had their quote £6400 and here`s what their customers have said
Both clients are reachable after work hours. I have just spoken to G's boss who is having a system with us this week. He tells us that his meter has actually gone backwards 600 kW/h since we installed the system in May, because this combination of SolarWorld panels and an Eltek 4.4 belts out so much power! (This is only possible with an old analogue type meter.)
SL0 -
Just had a further email from the supplier.
With the old analogue metres, when your PV system is producing more than you are consuming in your house, as it is back-feeding electricity back to the grid, it actually turns your meter dial backwards, reducing the final reading. This has left us with many ecstatic customers, who enjoy a further saving on their bills. It is not ours, or your responsibility to change the meter, it is up to your energy provider to contact you and pay to change it to a digital meter to cease this occurrence. This can take them months, a year or so, or often they don't get round to it at all. It's kind of like a temporary bonus courtesy of your favourite energy provider!0 -
I'm not sure that is correct, I believe you have to tell them. Whether they're very quick in getting round to changing it is another matter..0
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Evening SL. I'm probably being a bit harsh, but when a sales pitch, starts to turn into spin, I get a little nervous.
As silverwhistle said, you should notify your leccy company if the meter goes backwards. It's then up to them how long they take to replace it. However, they can try to bill you for those units, though calculating an accurate figure will be a total PITA.
My mate has a 3 yr old system and a backwards meter (fully notified), he doesn't plan to pay anything for units consumed over 12 months ago, but expects an interesting bill eventually. His meter won't go past zero (on the units dial), so if the day starts on 1 and he generates loads, he knocks off 1kWh, but if starts on a 9 he could knock up to 9 units off. Try working that one out and producing a bill!
Back to the super inverter. Looking at the tech sheets I get Euro efficiency ratings of:
Eltek Theia 4.4 96.9%
SMA SB3600TL 96.3%
Solar River 4000TL 97.1%
so all similar. Even if there was some clever software upgrade on the Eltek (and I'm very dubious) then my small brain can only see a max theoretical gain of 3.1%, or 3,600kWh's * 3.1% = 111.6kWhs. Total = 3,711.6kWhs!
It smells like a sales pitch designed to hook you with greedy hopes - I don't like those approaches as they make me doubt what else has been said.
Mart.Mart. Cardiff. 8.72 kWp PV systems (2.12 SSW 4.6 ESE & 2.0 WNW). 20kWh battery storage. Two A2A units for cleaner heating. Two BEV's for cleaner driving.
For general PV advice please see the PV FAQ thread on the Green & Ethical Board.0 -
Martyn1981 wrote: ».... Way out of my depth here, hopefully Roger or Zeup can comment, but this doesn't sound right to me. If the power is 16 * 250Wp, then that's what the inverter has to work with. A better inverter will be more efficient, but you are probably looking at 95%+ anyway. In fact a good inverter might be 96 to 98%, so there is very little room for improvement - the inverter can't create extra power, so unless your set up and location can send 4,300+kWh's to the inverter, there's no way it can come out the other end, even at 100% efficiency(?)
I'll look forward to a lesson from the clever guys. Hopefully they'll be along soon .....
... anyway, Mart's got it right .... the maximum power will be limited by either the panels or the inverter. It could be possible for the software algorithm which limits inverter output to be modified to handle the limiting process in a different way when cloud edge maximum conditions exist, but this would depend on the make/model and capability of the inverter in question, depending entirely on whether the inverter is hardware or software constrained. However, any change to a 4kWp array with a 4kW inverter would simply be a temporary condition whilst irradiation is high and panel temperatures are low ....
Seems like a lot of effort for a few extra kWh/year even if it was possible .... the difference looks to be described as a 7.5%(4300W/4000W) to 10%(4400/4000) advantage, but is likely to provide no more than a single digit kWh advantage over a year, so a fraction of a percentage ... for example, if 5kWh/year it would represent ~0.1% (5/3600) ....
As for the installer pushing the above and then seriously pushing savings resulting from backwards running analogue meters, I'd start to question their integrity ... smells of a salesman's desperation to me, especially considering that any potential saving can be reclaimed by the energy supplier and that a considerable proportion of analogue meters have a ratchet mechanism to prevent fraudulent reverse running anyway !! ...
I thought that the issue with roof space had been addressed by one offer being for SunPower high power density panels at a reasonable cost ....
HTH
Z"We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle0 -
Martyn1981 wrote: »Evening SL. I'm probably being a bit harsh, but when a sales pitch, starts to turn into spin, I get a little nervous.
As silverwhistle said, you should notify your leccy company if the meter goes backwards. It's then up to them how long they take to replace it. However, they can try to bill you for those units, though calculating an accurate figure will be a total PITA.
My mate has a 3 yr old system and a backwards meter (fully notified), he doesn't plan to pay anything for units consumed over 12 months ago, but expects an interesting bill eventually. His meter won't go past zero (on the units dial), so if the day starts on 1 and he generates loads, he knocks off 1kWh, but if starts on a 9 he could knock up to 9 units off. Try working that one out and producing a bill!
Back to the super inverter. Looking at the tech sheets I get Euro efficiency ratings of:
Eltek Theia 4.4 96.9%
SMA SB3600TL 96.3%
Solar River 4000TL 97.1%
so all similar. Even if there was some clever software upgrade on the Eltek (and I'm very dubious) then my small brain can only see a max theoretical gain of 3.1%, or 3,600kWh's * 3.1% = 111.6kWhs. Total = 3,711.6kWhs!
It smells like a sales pitch designed to hook you with greedy hopes - I don't like those approaches as they make me doubt what else has been said.
Mart.
Yes it does sound to good to be true will see if there any reviews about this company and see if they have fitted this system locally and then check out the feed back.
SL0 -
.... And as if by magic, the shopkeeper appeared .... (Don't you just miss it !!)
... anyway, Mart's got it right .... the maximum power will be limited by either the panels or the inverter. It could be possible for the software algorithm which limits inverter output to be modified to handle the limiting process in a different way when cloud edge maximum conditions exist, but this would depend on the make/model and capability of the inverter in question, depending entirely on whether the inverter is hardware or software constrained. However, any change to a 4kWp array with a 4kW inverter would simply be a temporary condition whilst irradiation is high and panel temperatures are low ....
Seems like a lot of effort for a few extra kWh/year even if it was possible .... the difference looks to be described as a 7.5%(4300W/4000W) to 10%(4400/4000) advantage, but is likely to provide no more than a single digit kWh advantage over a year, so a fraction of a percentage ... for example, if 5kWh/year it would represent ~0.1% (5/3600) ....
As for the installer pushing the above and then seriously pushing savings resulting from backwards running analogue meters, I'd start to question their integrity ... smells of a salesman's desperation to me, especially considering that any potential saving can be reclaimed by the energy supplier and that a considerable proportion of analogue meters have a ratchet mechanism to prevent fraudulent reverse running anyway !! ...
I thought that the issue with roof space had been addressed by one offer being for SunPower high power density panels at a reasonable cost ....
HTH
Z
Thanks Z,
The roof space issue regarding space is no longer a problem as the initial survey got the roof measurement incorrect, they quoted 7.0m x 5.0m should be 7.1m x 5.3m. Don`t know if this was a deliberate act(to stop me looking for a 16 panel system) or a genuine mistake but if i dont mind the effect of a portrait/landscape panel layout then the cost savings of perbright/solar world panerls against the the quality of sun world panel can`t be ignored.
SL0 -
I`m still intrigued and ignoring the exceptional issues and concentrating on the kit itself. The Eltek inverter looks a fairly decent piece of kit from what i can research there was a technical issue about a year ago but has since be sorted out with a software update. It`s a Norwegian company that makes it and has some very good reviews. Was awarded the `red dot` accreditation by Photon (international & independent trade magazine). Here`s their You tube video.
http://www.youtube.com/watch?v=loZ9klRQNMg
My question to all you tech wizards out there is what`s the effect of continually running the inverter at it`s maximum performance in terms of inverter life as the guarantee is 5 years though additional insurance of £100 gets you 10 years.
SL0 -
Has anyone heard of PV magazine and how can you get hold of it?
SL0
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