Solar IBoost+ experience

JKenH

Petriix said:

I think it's also mostly a myth (or wishful thinking) that self-consuming solar is 'greener' than burning gas. If you consider how the last bit of grid demand is met, burning gas at home is almost always greener than causing more demand on the electric grid. Exporting your solar usually does more good than not burning the equivalent amount of gas. It's optimal to minimise your demand and maximise your exports in most cases. 

Using electricity to heat water is cleaner than using gas to heat it, although there is an argument that whatever electricity we use as individuals comes from marginal generation. Using your own solar is no cleaner than using grid electricity as by using it the grid is deprived of your generation which would otherwise be powering your neighbours homes. 

paul991

all my electricity comes comes from pv and ripple. So if go to fully electric heating do I keep the gas on to heat my water.do we not get a heat pump

pensionpawn

JKenH said:

pensionpawn said:

JKenH said:

Petriix said:

It's really important to remember that any 'savings' from an iboost or similar cannot be measured by how many kWh you divert but by how many kWh of the cheapest alternative water heating you avoided; and those are definitely not the same. Today, with export prices at 15p and off-peak imports at 7.5p it's only in unusual circumstances that any diversion would make sense. The best thing is to minimise usage and maximise exports. 

In many cases what you say is correct and in our case, being on Octopus Flux, we are better off heating our water on a cheap overnight tariff than using a solar diverter. The daytime export rate is similar to Flux import (2-5am) but we shower in the mornings and so use the water soon after it is heated rather than leaving it to cool down in the tank. If your personal hygiene regime dictates you shower in the evening or when coming home from work and/or you wash up by hand in the evening then heating your tank from afternoon sunshine can make sense (depending on tariff) as you lose less heat from the tank. 

If you are on a very cheap overnight tariff like IOG (7.5p) and are paid export at 15p/kWh then, yes, ditch the diverter.

However if you have gas, you use that instead at 7.5p whenever you need hot water.

You can but that’s not very green. With a combi boiler it’s probably not too inefficient but if you have a traditional indirect hot water tank quite a bit of heat is wasted getting the water you want to use hot. 

How come? The green energy that I didn't use to heat my water has been exported and used by someone else to displace gas / coal. In a wider context replacing my 25 year old windows / gas boiler with new windows and a new condensing boiler has reduced my gas consumption by 20%

JKenH

pensionpawn said:

JKenH said:

pensionpawn said:

JKenH said:

Petriix said:

It's really important to remember that any 'savings' from an iboost or similar cannot be measured by how many kWh you divert but by how many kWh of the cheapest alternative water heating you avoided; and those are definitely not the same. Today, with export prices at 15p and off-peak imports at 7.5p it's only in unusual circumstances that any diversion would make sense. The best thing is to minimise usage and maximise exports. 

In many cases what you say is correct and in our case, being on Octopus Flux, we are better off heating our water on a cheap overnight tariff than using a solar diverter. The daytime export rate is similar to Flux import (2-5am) but we shower in the mornings and so use the water soon after it is heated rather than leaving it to cool down in the tank. If your personal hygiene regime dictates you shower in the evening or when coming home from work and/or you wash up by hand in the evening then heating your tank from afternoon sunshine can make sense (depending on tariff) as you lose less heat from the tank. 

If you are on a very cheap overnight tariff like IOG (7.5p) and are paid export at 15p/kWh then, yes, ditch the diverter.

However if you have gas, you use that instead at 7.5p whenever you need hot water.

You can but that’s not very green. With a combi boiler it’s probably not too inefficient but if you have a traditional indirect hot water tank quite a bit of heat is wasted getting the water you want to use hot. 

How come? The green energy that I didn't use to heat my water has been exported and used by someone else to displace gas / coal. In a wider context replacing my 25 year old windows / gas boiler with new windows and a new condensing boiler has reduced my gas consumption by 20%

That’s a reasonable argument if we can all agree that marginal electricity generation is from gas/coal but whenever I have suggested it is marginal generation from gas which is deployed when someone plugs in their EV in I am shot down in flames. 

paul991

you can only control what you do in your own house your neighbour may be wasting your excess so you may as well use

pensionpawn

paul991 said:

you can only control what you do in your own house your neighbour may be wasting your excess so you may as well use

Even if the accumulative savings (currently 12.5p / Kwhr) of selling spare solar energy at 20p to buy gas at 7.5p helps finance the purchase of a battery to allow me to minimise my electrical import?

paul991

what ever works for you .I am using  my usage savings and FIT to buy a  insulated garage door

Petriix

paul991 said:

you can only control what you do in your own house your neighbour may be wasting your excess so you may as well use

That's totally illogical. If your neighbours are wasting energy it's objectively better if it's coming from your roof (at profit to you) than from a power station. You should only ever use the energy you actually need. 

paul991

yes  but I am not burning gas  so no local pollution

andyg9053

I think I read on here last year, heating water in your home with gas with all possible loses is probably around 80% efficient. Whereas gas produced electricity is only about 50% efficient. This meant that exporting all of your excess was greener for the planet. I may be wrong as I didn’t do the working out.