Solar Panel Guide Discussion

zeupater

lanstrom wrote: »

I have been trying to input my own panel specs into the SMA software but it just keeps telling me that I can not have that combination of values (even when I exactly copied the details for the 220W that are already in the software).

These are the specs for the 230W panels ...

REW Premium Plus RPP230 UM60
Rated power (Pmpp) - 230
Rated voltage (Umpp) - 30.5
Rated Current (lmpp) - 8.20
Open-circuit voltage (Uoc) - 37.3
Short circuit current (lsc) - 8.70
Cell efficiency - 17.4%
Module efficiency - 15.3%
Max voltage - 1000
Temperature coefficient (Uoc) - -0.35% / deg c
Temperature coefficient (Pmax) - -0.40% / deg c
Temperature coefficient (lsc) - 0.065% / deg c
Outer dimensions - 1637 x 997 x 46
Weight - 19.5Kg

Could you have a go see if you can get the details into the SMA software, if you get chance please ?

Thanks.

Hi

It looks like the problem you were having is that the specs provided are wrong for a nominal 230Wp panel, they seem to be for a 250Wp unit, so assuming that the panel voltage is correct at 30.5V then the MPP current must be 7.54A, not 8.2A (VxA=W) ....

Based on the assumption above, 17 panels (3.91kWp) gives an annual yield of 3270.8kWh.y with your roof details & a SB4000TL inverter.

Looking at the problem with the 220W panels, it looks like the root cause is the same error, the details in the SMA database show 30.0V/8.1A which describes a 243W panel. Its likely that SMA don't check the logic behind the specs supplied by the manufacturers and simply append them to their database unchecked .....

Looks like REW need to address their spec sheets and SMA need to validate their database ...

HTH
Z

crazyletters

I've just spent the last two hours reading all the discussions on pros and cons of putting solar panels on the roof and conclude it makes a good long term investment and is a good way of ensuring at least a little of ones own 'free' energy.

My problem is I dont have the money upfont, so am considering putting it on several 0% credit cards and rolling over for a few years.

Any thoughts?

I have also looked at the 'try to buy' that Eon is offering which doesnt look so attractive as you only get to use the electricity but dont benefit from FIT, possibly paying more in the long run.

Any experience with this?

Many thanks.

thenudeone

crazyletters - As far as charges are concerned then as long as you can roll your BTs over every 12-18 months for a 3-4% fee, that's quite a cheap form of credit.
BUT what happens if you can't get a new deal in 12-18 months time? Perhaps the banks will be lending even less if Greece/Ireland/Spain defaults and won't be offering any 0% deals. (I remember the days before BT fees existed!). Where will you find £10-£12k to pay it off?
A safer route from that point of view would be to borrow more on your mortgage, if you have sufficient equity.

lanstrom

zeupater wrote: »

Looks like REW need to address their spec sheets and SMA need to validate their database ...

I'd agree. I was scrolling through the list of panels and one of them (I think it was either a Sharp or Sanyo) listed a yield of over 11,000 kWh.y ;-)

mpn226

Polesdenite wrote: »

I came on this forum to try to find some unbiased opinions about fitting Solar PV panels, a lot of people seem to be trying to show how clever they are but do any of them have panels? Is there enyone on this site that actually has them fitted, if so may I ask , if they work, do they generate the return claimed ? are they a good idea ? Even the Guardian blog, which is basically against the idea, says we would be crazy not to take it up , provided we can afford the outlay. So help me out here , don't drown me in jargon or political ideology just a straight answer please.

hi new to this forum, have had pv panels for over a year, YES they work and i live in N W Highlands, installed 10 ying li panels generating 2.35kw was lucky to get a 30% grant from energy saving trust and a 8 year interest free loan for the remainder on costs of 10K. panels have performed to expectations (apart from below par sunshine) figures from 31/12/2010 generated 1157 units, used ie bought in via meter 848 units, exported 873 units, yes have export meter fitted free from s&se, on current payback expect to achive 7.5-8.0% return on money, lot better than money in bank. am about to add futher 16 panels to system. In short i say go for it regards to ALL fred hughes:j:j

zeupater

mpn226 wrote: »

hi new to this forum, have had pv panels for over a year, YES they work and i live in N W Highlands, installed 10 ying li panels generating 2.35kw was lucky to get a 30% grant from energy saving trust and a 8 year interest free loan for the remainder on costs of 10K. panels have performed to expectations (apart from below par sunshine) figures from 31/12/2010 generated 1157 units, used ie bought in via meter 848 units, exported 873 units, yes have export meter fitted free from s&se, on current payback expect to achive 7.5-8.0% return on money, lot better than money in bank. am about to add futher 16 panels to system. In short i say go for it regards to ALL fred hughes:j:j

Hi & welcome to the forum ....

Thanks for the information. It's refreshing to see figures provided by another member with an export meter, especially so from someone with experience of having a system and accurate data for a considerable time who can therefore post from an objective viewpoint as opposed to the many subjective claims which seem to be made.

In summary ....

Of 1157kWh generated by a 2.35kWp system - 873kWh were exported, therefore a self consumption rate of just under 25%

Total consumption was 1132kWh (1157-873+848), of which 284kWh (1157-873) were contributed by the pv system, therefore a saving of fractionally over 25% on energy imported.

If you wouldn't mind, a question for clarity to many who read these threads but don't fully understand pv .... If you were to increase the size of your array by around 50% to 3.5kWp, do you have a view on whether you would still export [STRIKE]25%[/STRIKE] 75% of generation, or more, or less ?

Thanks
Z

mpn226

zeupater wrote: »

Hi & welcome to the forum ....

Thanks for the information. It's refreshing to see figures provided by another member with an export meter, especially so from someone with experience of having a system and accurate data for a considerable time who can therefore post from an objective viewpoint as opposed to the many subjective claims which seem to be made.

In summary ....

Of 1157kWh generated by a 2.35kWp system - 873kWh were exported, therefore a self consumption rate of just under 25%

Total consumption was 1132kWh (1157-873+848), of which 284kWh (1157-873) were contributed by the pv system, therefore a saving of fractionally over 25% on energy imported.

If you wouldn't mind, a question for clarity to many who read these threads but don't fully understand pv .... If you were to increase the size of your array by around 50% to 3.5kWp, do you have a view on whether you would still export 25% of generation, or more, or less ?

Thanks
Z

hi i am hoping to add extra 3.76kw onto my roof bringing total to over 6kw. All things being equal would expect to export 75% + during the day and buy in at night when the good old sun goes down. at the moment am exporting nearly all i generate during the day,i use approx 3 units daily from either pv or elecy co this will rise as we get shorter days.if you have any more queries let me know and will try to answer fred.:D

zorber

Just had my quote come through

They have also stated that i will need

Upgrade/install Main Equipotential bonding to 10mm2 (gas and water as Applicable) at a cost of £160.

Now my point is as my house is 10 years old why does it need this upgrade, if this upgrade is really needed then it would be needed by most installs, so why is it not part of the package price already.

It just smells like a con!!

John_Pierpoint

What did your other quotes include?
The wiring regulations have been changing, in your case it might make sense to quote you a figure for bringing your existing system up to date rather than install a parallel system just for the PV panels.
I would think the installer wants to link together your metal plumbing and gas pipes just in case some of them include plastic fittings so they could be at an non earthed potential - I remember the then "gas board" back in the 1970's fitting gas systems with a plastic washer, deliberately to stop electricians using the gas pipe as an earth.

[I live in a home with an electrical installation from the early 1970's, it has not killed me yet, it is simple, I understand it and I sleep well at night but I expect an electrician will now try to tell me I'm in dire danger :eek: BTW yes I do have one earth leakage circuit breaker;)]

Cardew

mpn226 wrote: »

hi i am hoping to add extra 3.76kw onto my roof bringing total to over 6kw. All things being equal would expect to export 75% + during the day and buy in at night when the good old sun goes down. at the moment am exporting nearly all i generate during the day,i use approx 3 units daily from either pv or elecy co this will rise as we get shorter days.if you have any more queries let me know and will try to answer fred.:D

Hi,
I take it that you are aware that 4kWp is the maximum size system for receiving the highest rate of FIT? i.e. if you enlarge the system to 6kWp all generated output will get the lower rate of FIT.