Solar, is it worth having a battery in my case scenario?

Martyn1981

shamanicone said:

Martyn1981 said:

shamanicone said:

Hi, I have room for about 13 x 460w Aiko panels with a 10 Kwh inverter (and that's the plan), I've been allowed 3.9 Kwh export by my DNO and I use 3200 Kwh average electricity a year. 

I currently don't have a heat pump or EV.

Is it worth my while having a battery at this stage based on my usage please (I've been quoted approx £3k extra for a Tesla PW3 and backup gateway over the panels)

Thanks 

Hi, like others have mentioned, a 10kW inverter is too big for 6kWp of panels, you'd really want about 5kW.

But that said, a 3.9kW inverter would be too undersized, and would lead to some clipping and loss.

Based on that, and what looks like a really good price for the PV + PW3, I'd say go for it. Even if the PW3 has to be capped to avoid export greater than 3.9kW, it will still be able to absorb the full ~6kW of generation from the panels, by storing it in the batteries (so long as the batts aren't full).

Plus the battery gives you a big potential benefit in the winter, where you could charge it with cheap rate leccy, then run the house off that through the day. Combined with the PV and storage in the sunnier months, you should be able to avoid almost all use of day rate leccy.

Of course this requires you to find and switch to a dual rate tariff, but it should save you. And having a battery and cheap rate leccy, should make other options in the future better, such as an EV charged cheaply overnight. Or something I'm a big fan off, and that's adding an air con unit, an air to air unit (A2A). With one of these, you can use spare PV to warm the house in the Spring and Autumn, when heating demand is low, and even pre-heat the house overnight on cheap rate in the winter, to reduce use of the gas central heating (GCH). [I've now gone a bit further, added a second A2A unit, and removed the GCH.]

So, for the price, and the better use of the large PV array, and future options, I think the battery is a good option for you, with potential future proofing built in.

So (as you are probably aware) the inverter is built into the PW3 (hence the larger size than required). The DNO has capped my export but not limited the inverter, my understanding is that means I can fill the battery at full throttle as it were, meaning about 2.5 hours for the PW3 to fully charge.

I'm going for a tariff that will charge me 7p overnight and pays 15p export - it's not intelligent, but I think I can set the PW to max this anyway (hopefully).

My thinking was also the future, and probably a later move to a heat pump (something that might be forced upon us anyway in the not too distant future) and who knows what is coming down the line geo politically (so a bit of self reliance might not be a bit thing if things get complicated in that regard). 

My last swaying factor towards going for it is I'm going to pay for it all over time on 0% credit cards - so it's not like it's going to take a huge chunk out of my growing savings. 

Thanks for the input

Thanks, makes more sense now. Like others I was a bit thrown by the 10kW inverter, thinking that was the no-battery option. The PW3 also has lots of PV inputs, so you could add even more PV in the future, if like many of us, it becomes a bit of an obsession.

I too thought it sounded a tad too good to be true at £9.5k as the PW3 and Gateway cost about £6k alone. But if that's the price, fill your boots.

Teeny question, you mention 7p import (and 15p export), that's a deal many of us are on with Octopus. Have you checked it's available, or just been told you can get it, as you typically need an EV to qualify. Not trying to be too negative, and there lots of deals out there, just not sure you can get as low as 7p without an EV. Hopefully I'm wrong, and deals have improved, which will be great news.

Of course, if you have off-road parking and hang around here too long absorbing the positive BEV waves, maybe that's a direction you will go, with for example, 10,000 miles of 'fuel' pa @ £200. 

shamanicone

Martyn1981 said:

shamanicone said:

Martyn1981 said:

shamanicone said:

Hi, I have room for about 13 x 460w Aiko panels with a 10 Kwh inverter (and that's the plan), I've been allowed 3.9 Kwh export by my DNO and I use 3200 Kwh average electricity a year. 

I currently don't have a heat pump or EV.

Is it worth my while having a battery at this stage based on my usage please (I've been quoted approx £3k extra for a Tesla PW3 and backup gateway over the panels)

Thanks 

Hi, like others have mentioned, a 10kW inverter is too big for 6kWp of panels, you'd really want about 5kW.

But that said, a 3.9kW inverter would be too undersized, and would lead to some clipping and loss.

Based on that, and what looks like a really good price for the PV + PW3, I'd say go for it. Even if the PW3 has to be capped to avoid export greater than 3.9kW, it will still be able to absorb the full ~6kW of generation from the panels, by storing it in the batteries (so long as the batts aren't full).

Plus the battery gives you a big potential benefit in the winter, where you could charge it with cheap rate leccy, then run the house off that through the day. Combined with the PV and storage in the sunnier months, you should be able to avoid almost all use of day rate leccy.

Of course this requires you to find and switch to a dual rate tariff, but it should save you. And having a battery and cheap rate leccy, should make other options in the future better, such as an EV charged cheaply overnight. Or something I'm a big fan off, and that's adding an air con unit, an air to air unit (A2A). With one of these, you can use spare PV to warm the house in the Spring and Autumn, when heating demand is low, and even pre-heat the house overnight on cheap rate in the winter, to reduce use of the gas central heating (GCH). [I've now gone a bit further, added a second A2A unit, and removed the GCH.]

So, for the price, and the better use of the large PV array, and future options, I think the battery is a good option for you, with potential future proofing built in.

So (as you are probably aware) the inverter is built into the PW3 (hence the larger size than required). The DNO has capped my export but not limited the inverter, my understanding is that means I can fill the battery at full throttle as it were, meaning about 2.5 hours for the PW3 to fully charge.

I'm going for a tariff that will charge me 7p overnight and pays 15p export - it's not intelligent, but I think I can set the PW to max this anyway (hopefully).

My thinking was also the future, and probably a later move to a heat pump (something that might be forced upon us anyway in the not too distant future) and who knows what is coming down the line geo politically (so a bit of self reliance might not be a bit thing if things get complicated in that regard). 

My last swaying factor towards going for it is I'm going to pay for it all over time on 0% credit cards - so it's not like it's going to take a huge chunk out of my growing savings. 

Thanks for the input

Thanks, makes more sense now. Like others I was a bit thrown by the 10kW inverter, thinking that was the no-battery option. The PW3 also has lots of PV inputs, so you could add even more PV in the future, if like many of us, it becomes a bit of an obsession.

I too thought it sounded a tad too good to be true at £9.5k as the PW3 and Gateway cost about £6k alone. But if that's the price, fill your boots.

Teeny question, you mention 7p import (and 15p export), that's a deal many of us are on with Octopus. Have you checked it's available, or just been told you can get it, as you typically need an EV to qualify. Not trying to be too negative, and there lots of deals out there, just not sure you can get as low as 7p without an EV. Hopefully I'm wrong, and deals have improved, which will be great news.

Of course, if you have off-road parking and hang around here too long absorbing the positive BEV waves, maybe that's a direction you will go, with for example, 10,000 miles of 'fuel' pa @ £200. 

I will send you a PM - it's not with Octopus and they have said you dont need an EV

Martyn1981

shamanicone said:

Martyn1981 said:

shamanicone said:

Martyn1981 said:

shamanicone said:

Hi, I have room for about 13 x 460w Aiko panels with a 10 Kwh inverter (and that's the plan), I've been allowed 3.9 Kwh export by my DNO and I use 3200 Kwh average electricity a year. 

I currently don't have a heat pump or EV.

Is it worth my while having a battery at this stage based on my usage please (I've been quoted approx £3k extra for a Tesla PW3 and backup gateway over the panels)

Thanks 

Hi, like others have mentioned, a 10kW inverter is too big for 6kWp of panels, you'd really want about 5kW.

But that said, a 3.9kW inverter would be too undersized, and would lead to some clipping and loss.

Based on that, and what looks like a really good price for the PV + PW3, I'd say go for it. Even if the PW3 has to be capped to avoid export greater than 3.9kW, it will still be able to absorb the full ~6kW of generation from the panels, by storing it in the batteries (so long as the batts aren't full).

Plus the battery gives you a big potential benefit in the winter, where you could charge it with cheap rate leccy, then run the house off that through the day. Combined with the PV and storage in the sunnier months, you should be able to avoid almost all use of day rate leccy.

Of course this requires you to find and switch to a dual rate tariff, but it should save you. And having a battery and cheap rate leccy, should make other options in the future better, such as an EV charged cheaply overnight. Or something I'm a big fan off, and that's adding an air con unit, an air to air unit (A2A). With one of these, you can use spare PV to warm the house in the Spring and Autumn, when heating demand is low, and even pre-heat the house overnight on cheap rate in the winter, to reduce use of the gas central heating (GCH). [I've now gone a bit further, added a second A2A unit, and removed the GCH.]

So, for the price, and the better use of the large PV array, and future options, I think the battery is a good option for you, with potential future proofing built in.

So (as you are probably aware) the inverter is built into the PW3 (hence the larger size than required). The DNO has capped my export but not limited the inverter, my understanding is that means I can fill the battery at full throttle as it were, meaning about 2.5 hours for the PW3 to fully charge.

I'm going for a tariff that will charge me 7p overnight and pays 15p export - it's not intelligent, but I think I can set the PW to max this anyway (hopefully).

My thinking was also the future, and probably a later move to a heat pump (something that might be forced upon us anyway in the not too distant future) and who knows what is coming down the line geo politically (so a bit of self reliance might not be a bit thing if things get complicated in that regard). 

My last swaying factor towards going for it is I'm going to pay for it all over time on 0% credit cards - so it's not like it's going to take a huge chunk out of my growing savings. 

Thanks for the input

Thanks, makes more sense now. Like others I was a bit thrown by the 10kW inverter, thinking that was the no-battery option. The PW3 also has lots of PV inputs, so you could add even more PV in the future, if like many of us, it becomes a bit of an obsession.

I too thought it sounded a tad too good to be true at £9.5k as the PW3 and Gateway cost about £6k alone. But if that's the price, fill your boots.

Teeny question, you mention 7p import (and 15p export), that's a deal many of us are on with Octopus. Have you checked it's available, or just been told you can get it, as you typically need an EV to qualify. Not trying to be too negative, and there lots of deals out there, just not sure you can get as low as 7p without an EV. Hopefully I'm wrong, and deals have improved, which will be great news.

Of course, if you have off-road parking and hang around here too long absorbing the positive BEV waves, maybe that's a direction you will go, with for example, 10,000 miles of 'fuel' pa @ £200. 

I will send you a PM - it's not with Octopus and they have said you dont need an EV

Many thanks shamanicone, it hadn't occurred to me that some of the EV deals may also be open to those with home batts.

That's really good news, as I'm often suggesting the option of an A2A heatpump unit (aircon effectively, but also heats) as a relatively cheap way to add some cheap and low carbon heat. But then it dawned on me that the best deals need an EV, and I couldn't find any deals under ~10p/kWh. So now I can keep suggesting the idea, if folk have batteries.

Always great to start the day with good news and more options. 

Screwdriva

Who is this tariff with & what’s it called?

debitcardmayhem

Screwdriva said:

Who is this tariff with & what’s it called?

And do they have a good SEG rate?

QrizB

Possibly Good Energy?

Martyn1981

QrizB said:

Possibly Good Energy?

Yep, that's the one I was told about. Hopefully there are more.

Qyburn

shamanicone said:

I will send you a PM - it's not with Octopus and they have said you dont need an EV 

Is that published (I can't see where) or did you specifically ask?

Qyburn

shamanicone said:

I'm going for a tariff that will charge me 7p overnight and pays 15p export - it's not intelligent, but I think I can set the PW to max this anyway (hopefully).

Just on that point, and based on my experience with 8.5kWp panels and 6kW export, you will need a balancing act for overnight charging. If the battery's fully charged overnight then any generation over house load + 3.9kW will be simply wasted.