Considering getting a Powerwall

[MrBadger]

Apologies, I had started writing this this morning, but decided that before posting I needed to double check some facts with a contact of mine at National Grid who works on the balancing system. As it will probably take a few weeks, and a few beers/coffees, and for me to ask questions that he can answer, I deleted most of the post.

Alas, I asked the question, but the opportunity to get the answers over a few beers never materialised and is unlikely to for a very long time

But the video below is not a bad one, but unfortunately does not answer the question of, when I flick a switch to charge my car/topup my battery, where does that power come from? It partially covers it when price plunging ("0 carbon"), but thats a rarity and tbh, I'm more interested in the winter or average figures. One comment to note, that of getting carbon below 50g CO2/kWh for the first time.

 

[Mr Miserable]

when I flick a switch to charge my car/topup my battery, where does that power come from?

Does this gridwatch.co.uk help?

 

[MrBadger]

More complex than that. I'm after the marginal power source that has to change when you flick the switch - I believe it is most often than not a fine balancing act followed by combined cycle gas turbine (CCGT) followed by being assimilated into other demand vs predictive use.

 

[Mr Miserable]

More complex than that. I'm after the marginal power source that has to change when you flick the switch - I believe it is most often than not a fine balancing act followed by combined cycle gas turbine (CCGT) followed by being assimilated into other demand vs predictive use.

I'm fresh out of marginal power sources I'm afraid...

 

[eadsd]

I’m in Austin, TX. I had 5kw solar panels installed last August and I upgraded them a few weeks ago to 7kW. The location of the panels means I get longer production at a slightly higher level (5kW) throughout the day in peak summer. I had two Powerwalls and the energy gateway installed with the original system. I absolutely love it. I can see how much energy I’m using in near real time and I’ve adjusted my lifestyle in relatively easy ways to cut 30-40% of my usage. I’m now close to being completely off grid in this 100+ degree Fahrenheit heat and I suspect I’ll be a net producer much of the rest of the year. The payback time is probably 25-30 years for me but I can afford it so it’s more important to me to know I’m off grid and not using fossil fuels most of the time. My rates in Texas are pretty low (<10 cents US/ kWh) but we get a lot of sun compared to the UK. BTW regarding switching on and off the grid, it’s completely imperceptible here on our grid. Occasionally there’s a flicker of the grid goes down (with it has down 6-7 time in 12 months) but it’s no different that what happens on grid when there are massive disruptions like that.

 

[tsh2]

Curious if anyone has looked at flow batteries - not so good for peak power, but potentially cheaper if they actually exist in a small enough size for domestic use - and I think far better for cycle life.

 

[Dilly]

My two Powerwalls easily charge from my 10.9kw PV this time of year. Winter not so well so top up from off peak.
Back in May, I had the PW settings tweaked so they balance import better. My grid use is now down to a nominal 1Kwh per week. Roughly 130Wh per day

 

[gangzoom]

Despite a reasonable amount of rain, and starting to do longer trips another month where our standing charge makes up a large proportion of our electricity bill.

Currently its looking like even with a smallish 4KW PV system for 6 months of the year with the help of the PW or grid electricity use really is minimal.