Free solar panel discussion

Jon_Tiffany

Cardew wrote: »

and apart from very prief periods in Summer you won't run appliances like an immersion heater.

Disagree completely with that statement. Its only April and I have seen my system max out on many days. I would say that from April to September you are going to get a good number of days of maximum (or close to maximum) output where you could run an immersion heater.

Many people have been reporting excellent output for March as well this year, my system was around 20% above estimate.

This only applies if you have a larger 3-4kWp system, or have fitted a lower rated immersion heater (say a 1kW).

Jon_Tiffany

Been working abroad for a while and just caught up with some of the posts on here. I'm very surprised at some of the comments regarding the free solar contracts, the straight line depreciation works massively in the landlords favour. Anyone who has one of these contracts is onto a winner in my opinion.

I'm not surprised that these companies are changing their contracts, unless they do so they are very likely to go bust when everyone buys out the panels in a few year. If someone had offered me a such a contract I would of taken up the offer (rather than buying my own) and then bought them out in about 5 years once the FITs have gone up nicely due to inflation and the buyout price has come down.

Cardew

Jon_Tiffany wrote: »

Speaking for myself, I use gas heating in the winter and you may be surprised to hear that I need electric just as much in the summer as well!

I'm not saying that running electric heaters with solar pv is viable, but I had a quite a few days in December where we were generating around 900w (my system is only small) and could have powered a 1200w halogen heater on the first or second setting - available from Argos.

I think the point being made is how do you cost savings if you run your halogen heater on two elements(800 watts) of even if someone runs a 3kW immersion heater in mid summer.

People like to cost the 3 kW immersion heater as giving 30p an hour savings i.e. 3kWh @ 10p.

However if you have gas the saving is only about one third of 30p an hour, as you would use gas normally. Also as pointed out earlier, if your output drops to 2kW, you 'import' 1kW and it is costing more than gas.

Jon_Tiffany

Cardew wrote: »

I think the point being made is how do you cost savings if you run your halogen heater on two elements(800 watts) of even if someone runs a 3kW immersion heater in mid summer.

People like to cost the 3 kW immersion heater as giving 30p an hour savings i.e. 3kWh @ 10p.

However if you have gas the saving is only about one third of 30p an hour, as you would use gas normally. Also as pointed out earlier, if your output drops to 2kW, you 'import' 1kW and it is costing more than gas.

Yes, agree that if you use gas for your heating you are saving around 3p per kWh.

However, some people don't have gas so for them the saving is around 30p an hour.

Reading the other threads on the electric forum some people are paying around 12-13p per kWh, so for those the savings are even bigger. Although if you are paying those prices you would probably save even more by switching supplier.

The point I was making is that most people need electric just as much in the summer as they do in the winter.

The other point I was making is that you can run an electric heater from solar PV in the winter if you want to. Although its only going to make a very tiny contribution to your overall heating.

Jon_Tiffany

digitaltoast wrote: »

If FiTs take off in the way people want them to, and let's say one in every 4 houses has panels, then by the virtue of basic maths the electricity bills of the old, the poor, the underclass without large south facing properties they own, will be roughly quadruple.

Electric bills will rise by around £6 a year due to FITs. Electric bills quadrupling is laughable and insanely wrong!

And anyway, there will never be as much as one house in four having solar. That would give a capacity of around 15,000,000kWp!!!!

I doubt we will even see as many as 1 in 100 houses with solar pv within the next ten years!

PeterZ_2

Jon_Tiffany wrote: »

Electric bills will rise by around £6 a year due to FITs. Electric bills quadrupling is laughable and insanely wrong!

And anyway, there will never be as much as one house in four having solar. That would give a capacity of around 15,000,000kWp!!!!

I doubt we will even see as many as 1 in 100 houses with solar pv within the next ten years!

Electricity consumption between 8am and 4pm was fairly flat today at somewhere around 35,000MW and demand will drop off sharply from around 8pm. Peak demand today was around 10am, just at the time where solar pv output would be ramping up.

So with 15,000MW of solar it could have provided somewhere around 40% of our daytime electricty needs for today.

I think you are being a little pessamistic, I think its feasible for around 1 in 20 houses to have solar pv. If you then add in some warehouse roofs and community projects then that target could be reached.

This combined with some modern design nuclear power would give us energy security and independance. Even despite the problems in Japan I would much prefer a nuclear power station over coal fired, much more flexible as well.

digitaltoast

PeterZ wrote: »

Electricity consumption between 8am and 4pm was fairly flat today at somewhere around 35,000MW and demand will drop off sharply from around 8pm. Peak demand today was around 10am, just at the time where solar pv output would be ramping up.

Graph from http://www.nationalgrid.com/uk/Electricity/Data/Realtime/Demand/demand24.htm for today, 16th April 2011.



Actually, we can see that peak was around 8am, tailing off after that. Yes, solar was "ramping up", ready to peak at 14:00 as demand was dropping off.

And this graph is from http://www.swea.co.uk/photovoltaics.shtml which says "The graph below shows the output curves on a near-cloudless sunny day", for the 8th April.



If anyone knows where to find the historical data for 8th April on the national grid site, I'd be happy to do a day-for-day comparison, but I don't think there's gonna be a lot in 8 days difference.

Can you explain how your observations fit with these graphs?

PeterZ_2

Yes, exactly - as your graphs show the output from solar is from ramping up by 10am and continues through at a good level until 5pm. It s a good fit.

PeterZ_2

Something like this:

PeterZ_2

Note that the above diagram is not to scale as it starts at 22,000MW, the red line for solar output should be further down, with the peak being around 15,000MW.