How we reduced our heating gas consumption by 25%

Screwdriva

paul991 said:

yes  but  your problem will be with a 4 kw system a lot of the time you will be importing for a 3 kw immersion

We appear to import minimal amounts from the 11-1pm peak generation window, if at all.

EricMears

Screwdriva said:

paul991 said:

yes  but  your problem will be with a 4 kw system a lot of the time you will be importing for a 3 kw immersion

We appear to import minimal amounts from the 11-1pm peak generation window, if at all.

That might not prove your panels were supplying enough electricity to (almost) supply immersion.  If tank is well lagged and very little hot water used in that period,  immersion would be off most of time.

Screwdriva

EricMears said:

That might not prove your panels were supplying enough electricity to (almost) supply immersion.  If tank is well lagged and very little hot water used in that period,  immersion would be off most of time.

I have attached a graph for a typical clear sunny summer day. Should do the explaining about immersion supply.

Our hot water consumption pattern ensures the tank will always be depleted prior to 11am.

2nd_time_buyer

Screwdriva said:

EricMears said:

That might not prove your panels were supplying enough electricity to (almost) supply immersion.  If tank is well lagged and very little hot water used in that period,  immersion would be off most of time.

I have attached a graph for a typical clear sunny summer day. Should do the explaining about immersion supply.

Our hot water consumption pattern ensures the tank will always be depleted prior to 11am.

Is there such a thing as a "typical clear sunny summer day" in the UK? 

Verdigris

It's called a hen's tooth, hence the shape of the graph.

Screwdriva

2nd_time_buyer said:

Is there such a thing as a "typical clear sunny summer day" in the UK? 

I checked 2021 (which wasn't anywhere as clear as 2020) and I counted 30 such graphs.

QrizB

Screwdriva said:

2nd_time_buyer said:

Is there such a thing as a "typical clear sunny summer day" in the UK? 

I checked 2021 (which wasn't anywhere as clear as 2020) and I counted 30 such graphs.

1 day in 12, ish? That's more than I'd have guessed!

2nd_time_buyer

QrizB said:

Screwdriva said:

2nd_time_buyer said:

Is there such a thing as a "typical clear sunny summer day" in the UK? 

I checked 2021 (which wasn't anywhere as clear as 2020) and I counted 30 such graphs.

1 day in 12, ish? That's more than I'd have guessed!

I get the same shape on a constantly cloudy day too. Only the output is about 1/10th!

EricMears

Screwdriva said:

EricMears said:

That might not prove your panels were supplying enough electricity to (almost) supply immersion.  If tank is well lagged and very little hot water used in that period,  immersion would be off most of time.

I have attached a graph for a typical clear sunny summer day. Should do the explaining about immersion supply.

Our hot water consumption pattern ensures the tank will always be depleted prior to 11am.

From that graph,  if your immersion is the normal 3kW job and nothing else in house was running you would have avoided imports between 11am & 2pm.  When immersion had been running for 3 hours tank might have got to temperature.

Magnitio

You can get lower power immersion heaters which provide more flexibility. I've installed a 1.5kw immersion controlled by a TP-Link HS110 smart plug that allows scheduling and also records energy consumption.