Author Topic: How big a system can I have  (Read 8298 times)

Berkshire Boy

  • Joined May 2011
  • Presteigne, Powys
How big a system can I have
« on: June 28, 2012, 03:40:46 pm »
We are looking in to installing solar panels, we use about 10,000 kw a year. I've just had a quote from the first company we have been to and the system will generate 3,100kw a year. Is there a limit to what you can generate I was hoping to go a lot higher than that.
Everyone makes mistakes as the Dalek said climbing off the dustbin.

Greenerlife

  • Joined Mar 2009
  • Leafy Surrey
Re: How big a system can I have
« Reply #1 on: June 28, 2012, 04:34:58 pm »
Our system (16 panels) is at the top end of the FIT for personal use which I think is 3920kw.  You can go as large as you like I believe, but the tariff drops significantly over this level. Having said that, we have already produced 1500kw hours since March.  Without a doubt, the best 'investment' we have ever made.

Olly398

  • Joined Mar 2010
  • Herts
    • Brixton's Bounty
Re: How big a system can I have
« Reply #2 on: June 28, 2012, 04:41:44 pm »
There are effectively four things limiting how "big" you can go:
 
1) Space for the panels. Assuming these are to be roof mounted, this equates to about 30m2 of south/sw facing roof. Do you have more?
 
2) Capital cost. More generation requires more panels, simples.
 
3) FITs - see above post - not a limit per se
 
4) How much you can use on site - a more subtle question. You can export electricity to the grid, but its much more beneficial financially for you to use it on site, so lets assume that is the intention. You use 10,000 kilo-watt-hours (kWh) a year. However, I would wager that at least half of that is in the evenings and through the night, when the sun aint shining! Without battery storage (not cost effective if you are at mains voltage), you can't reach that demand...   you can and should use a bit of demand side management, i.e. putting your appliances (dishwasher? washing machine?) on a timer to run in the daytime, but you will always face this limit.
 
HTH. Olly  :wave:
also blogging at...

      Brixton's Bounty

lachlanandmarcus

  • Joined Aug 2010
  • Aberdeenshire
Re: How big a system can I have
« Reply #3 on: June 28, 2012, 04:45:50 pm »
The other thing to watch out for is the limits imposed for renewables set ups where you have single phase connection to the grid (most domestic houses) rather than 3 phase(mainly in place in factories and larger farms and very expensive usually to get put in if you dont have it).You can install a system of up to 16 amps per phase without asking permission of the Distribution  Network Operator. Above that level you have to ask permission and they may after examining the set up/premises etc, decline if they choose.

Berkshire Boy

  • Joined May 2011
  • Presteigne, Powys
Re: How big a system can I have
« Reply #4 on: June 29, 2012, 10:14:02 am »
Thanks all for your replies.
Olly you are right I hadn't taken into account night time ??? Like you say I expect half our usage is evenings especially in the winter. I do have more roof space but I see what you mean about using what I generate rather than selling to the grid. The FITs aren't the sole reason for doing it I am more interested in having control over my electricity generation,it worries me that government is holding back on building new power stations wether nuclear or solid fuel. I can see in 10 years them realising we have knackered power stations and nothing to replace them.
Everyone makes mistakes as the Dalek said climbing off the dustbin.

HappyHippy

  • Guest
Re: How big a system can I have
« Reply #5 on: June 29, 2012, 11:01:38 am »
Sorry, coming to this a bit late  :-\
 
We enquired about getting some panels (we have a HUGE south facing roof) we ended up not going for them as it happens, but if you want a bigger set up look to the commercial installations.
I think the one we were quoted for was 4 times the size of a standard (is it 4Kw system normally?) for around £28K, but as we don't have the money sitting aside and would have had to take finance on it, it just worked out too expensive for us (what with having to still pay for electric when it's dark and having no way to 'store' extra power generated for later use)
I think it's a great thing to be able to 'grow your own' power, but unless you have the spare cash or a huge desire to be self sufficient, it doesn't give you the level of savings or income that it's portrayed to (by the salesman who comes to tell you all about it - don't ask anything technical about it  ::) ) especially since they reduced all the FIT's etc.
I'm looking more to the small wind turbines myself now  ;)  Got plenty of that here  ;D
Good luck though and keep us posted with what you do BB
Karen  :wave:

chrismahon

  • Joined Dec 2011
  • Gascony, France
Re: How big a system can I have
« Reply #6 on: June 29, 2012, 09:22:27 pm »
I wouldn't count on Feed in Tarrifs remaining in place. They stopped them in Germany after 5 years as it was costing too much. If too much electricity is fed in when the sun comes out the grid system would overbalance and they would end up have to use more fuel thirsty fast start generators. That defeats the objective. It will be necessary in my opinion to more evenly balance inputs from wind and solar to smooth out the feed in. That means more domestic wind generation is required. But personnally I would only install a scheme based on my own usage and would ignore the current financial incentives.

GreenMakeover

  • Joined Jul 2012
Re: How big a system can I have
« Reply #7 on: July 11, 2012, 09:18:26 pm »
ChrisMahon: you are perfectly right that the correct balance for renewables will be for a mixed technology portfolio. Just to clarify that the FIT is actually still operating in Germany. You are right that the FITs wont be around forever though, but that is only for newcomers. The reason for this is that it wont be long until solar PV will stack up without any incentives because of the reducing cost of hardware and the rising cost of electricity.
The good news however is that if you install a solar PV system now you will secure the revenue for 25 years regardless of future changes for newcomers to the scheme.

ShaunP

  • Joined Dec 2009
    • Timber Chalets and Lodges
Re: How big a system can I have
« Reply #8 on: July 14, 2012, 05:24:28 pm »
My neighbour has just installed a system. We are always having power cuts, not normally for very long but a pain when it happens. It turns out when we have a power cut he cant use his solar panels as the inverter is mains powered. It is a safety feature for the grid operators. If they are dealing with damaged cables they dont want solar power coming down from the other end!!!

Small Farmer

  • Joined Jan 2012
  • Bedfordshire
Re: How big a system can I have
« Reply #9 on: July 16, 2012, 12:18:05 am »
You can get a break before make switch to put on the supply cable to switch between mains supply and  a small generator when the power goes. That will drive the inverter.
Being certain just means you haven't got all the facts

 

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