Upgrade your SolarEdge system with Tesla’s battery storage

MarkBargain

I received an email today from SolarEdge titled 'Reduce your electricity bills - upgrade your SolarEdge system with Tesla’s battery storage'.

It states:

We are reaching out to you with a special offer to add a battery storage solution to your SolarEdge PV system.
SolarEdge has recently launched our battery storage solution in partnership with Tesla's Powerwall Home Battery.
Our StorEdge™ DC coupled storage solution will allow you to maximise self-consumption of your PV power. During the daytime, unused PV power is stored in a battery, and can be used at a later stage according to your house consumption needs. This allows you to minimise your electricity bills and gain energy independence.

It then invites me to complete a form to express an interest. I don't think I will as A) I understand these batteries and expensive and We get paid 50% of generation so I guess having a battery to store what we don't use would invalidate that!?

Still, it's good if these batteries are nearing readiness from the market, I hope they are a success and boost solar.

Ectophile

I'm not sure what you mean by (B).

You get paid the FIT on 100% of what you generate regardless of whether you use it or export it.

You are supposed to get paid for any electricity you export. However, most people don't have an export meter, so there's no way to measure that. Instead it is assumed that 50% of what you generate is exported.

EricMears

(A) Batteries have indeed been very expensive in the past and probably remain so. But if Tesla can stimulate the market enough prices will drop. It worked with colour TVs and it seems to have worked with PV. Maybe worth expressing an interest to see if they're offering any sort of incentive ?


(B) As Ectophile says, FIT is paid on all you generate whether you use it or give it away. And, estimating deemed export at 50% works in favour of the electricity companies and against the interests of most FIT claimants. Why shouldn't you do your bit to reverse that trend. If at some time in the future an accurate export meter is forced upon you, it's still likely to work out that keeping your own electricity is more economic than selling it at the pitiful rates offered.

Exiled_Tyke

Well I responded to the offer. I thought it would be worth seeing if the price is reasonable. I'm not expecting the maths to work out in my favour but it's still worth finding out.

Martyn1981

Something to consider is the cost in FiT losses.

The SolarEdges system uses a DC to DC charge on the batt. It monitors export and then directly charges the batt before inverter 'conversion'.

This is highly efficient, around 92%, then the batt discharges through the inverter to AC (as normal) when needed, but that's still some loss of generation prior to the TGM.

So if you used 1,000kWh of leccy from storage, then that probably involved about 1,100kWh gross.

I think the older SolarEdge inverters aren't compatible, but can't remember the date when they do become compatible, perhaps 2013/14?

For those on the highest FiT rate, they may need an inverter upgrade, and will 'lose' FiT on ~100kWh or so, depending on the success of the system.

An AC-DC-AC storage system that diverts excess leccy after the TGM to a battery (like a diversion switch), won't lose FiT income, but will have higher system losses.

Mart.

Markj1110

I have also responded, I will see what I get back.

EricMears

Martyn1981 wrote: »

Something to consider is the cost in FiT losses.

The SolarEdges system uses a DC to DC charge on the batt. It monitors export and then directly charges the batt before inverter 'conversion'.

This is highly efficient, around 92%, then the batt discharges through the inverter to AC (as normal) when needed, but that's still some loss of generation prior to the TGM.

(my italics etc)
. . . ..

Mart.

Surely, in that scenario you would lose FIT (and deemed generation) payments for all (indeed all + 8%) the electricity used to charge your battery Hence some of us would be paying more than 50p per unit to store electricity rather than buying it in at 15ppu ! :eek:

Martyn1981

EricMears wrote: »

Surely, in that scenario you would lose FIT (and deemed generation) payments for all (indeed all + 8%) the electricity used to charge your battery Hence some of us would be paying more than 50p per unit to store electricity rather than buying it in at 15ppu ! :eek:

Nope. As the leccy is discharged by the batt, it will flow through the inverter and then the TGM, before reaching the CU and being consumed by the household.

Only the losses (heat?) won't be 'felt' by the TGM.

Mart.

[Edit: Sorry Eric, that reads really snotty, or really snooty, apologies. Hi by the way. M.]

Martyn1981

EricMears wrote: »

Hence some of us would be paying more than 50p per unit to store electricity rather than buying it in at 15ppu ! :eek:

Just to put some numbers on this, and sticking with the ability to consume 1,000kWh of leccy (probably about right for me).

So, 1,000kWh of stored leccy used to displace 1,000kWh of import. If at 15ppu, then a saving of £150.

If the used 1,000kWh, required 1,100kWh of leccy to be stored, the FiT losses on the oldest, highest rate, would be approx 100kWh at 50ppu, so a loss of £50.

Thus an annual saving of approx £100, and a ten year battery life saving of perhaps £1k. That's why I think the cost needs to be around £1k for a system to work, for me.


I'm in no way criticising battery deployment, as this is really important for the future integration of more renewable generation and to speed up the cost reduction of the technology, but at the moment we would see a net loss in CO2 savings due to system losses. However, there would/could be economic savings for households, and also the industry, as less (expensive) leccy would be needed at peak times when the price can soar to double (or even 100's of times more) that of daytime leccy spot prices.

It's all great news moving forward.

Mart.

MarkBargain

Ectophile wrote: »

I'm not sure what you mean by (B).

You get paid the FIT on 100% of what you generate regardless of whether you use it or export it.

You are supposed to get paid for any electricity you export. However, most people don't have an export meter, so there's no way to measure that. Instead it is assumed that 50% of what you generate is exported.

Thanks for the clarification. I was just wondering if there was anything buried in the T&Cs about not being allowed to keep all the power, but I guess not.

I do use some batteries already e.g. charging laptops, toothbrushes, radios, night lights, phones and USB batteries (for phones and tablets) during the day, but a proper battery would be good so I will express an interest too in that case.

Sterlingtimes

In considering a long-term investment decision for batteries if may well be appropriate to consider that all exported electricity will be metered in due course.

Currently I am compensated for my export at 4.85p/11.04p = 44%.

I currently use 62% solar generated electricity (before immersion diversion). I would expect to increase this upon retirement. I cannot see that batteries would be a good investment.

Presumably, batteries could work better for those who export most of their production.