Adding battery to existing solar PV system - any thoughts/advice please.

JKenH

I am looking to add a battery to my existing solar system (details of which are in my signature). I have received the quote below from a local supplier for a 10kWh system with the potential to charge/discharge at 5kW. 

As requested, please find below your quotation for works. 

 

Solis 5kw AC Coupled Inverter:

 

• Programmable working modes.
• Remote upgrading and real time monitoring.
• Retrofit any standard PV systems to be able to run battery.
• 10-Year warranty

Duracell Battery Storage:

 

• 2 x Duracell Dura-5 (10.24 kwh capacity). 
• LifePo4 battery, safe, longer life span.
• Full 1C charge/discharge rates (5000w power delivery).
• Modular up 160kw+ 
• Manufactured in the United Kingdom
• Compact Design
• 10-year warranty.
• 8000 cycle Lifespan
• Force charge settings to allow “off peak charging”
• AI smart charging 
• Weather integration
• Duracell energy remote monitoring & data collection app.
• 90% depth of discharge.
• IP65 rated as "dust tight" and protected against water.

Total cost - £5,800.00 0% VAT applies.

 

On the face of it the quote seems quite high as from looking at trade sites the wholesale cost of the inverter comes in around £600 and the batteries about £2,600 = £3200 in total.£2600 for the installation* appears on the high side.

Previously my DNO, Northern Powergrid has been a bit obstructive wanting to count the potential discharge rate of the battery as a barrier. I currently have a 7.3 kW export limit. The potential supplier is a bit wary of NP usually dealing with WPD. (We are just over the DNO border.) 


Any thoughts, or alternative suggestions for suppliers, anybody, please? Postcode is DN21.

Edit: *even including profit margin. I am thinking it should come in a tad under £5k. Might be worth adding another 5kWh battery module to get the /kWh cost down.

QrizB

I look forward to @Screwdriva letting us know what the current going rate for a Tesla Powerwall 3 is but I'd guess around £7k?

That would give you a bigger battery and qualify you for Intelligent Octopus Flux, if that floats your boat.

JKenH

QrizB said:

I look forward to @Screwdriva letting us know what the current going rate for a Tesla Powerwall 3 is but I'd guess around £7k?

That would give you a bigger battery and qualify you for Intelligent Octopus Flux, if that floats your boat.

Thanks. I am currently on Agile and quite enjoy checking out the daily rates. I just need something to tide me over the peak teatime rates atm. I suppose with IOF I could do better but haven’t checked the rates out. Is a 10kWh battery big enough for arbitrage in winter? Does IOF charge/discharge the battery several times a day?

debitcardmayhem

As well as a powerwall you could consider a Givenegy all-in-one + gateway, not sure of the cost though , as @QrizB says @Screwdriva is the guru

JKenH

@Screwdriva I would welcome any observations you may have. TIA.

Screwdriva

The PW3 is typically added on for just over £7K installed (I do my best to pressure the installer to maximize competitiveness for MSE forum members). The 11kWh theoretical maximum discharge rate can be very handy on intelligent Flux, even with a 7kWh discharge limit. There isn't much difference in the price of the AIO and PW3 and the former is about to be replaced by an entirely new generation AIO 2.0 battery inverter, which should have its share of teething issues I'd imagine. Then there's the PW3's Stormwatch, Class leading off grid , outdoor and cold weather performance & an unmatched after sales and safety record. 

The estimated cost above includes a DNO re-application, should you decide to go down this route & a 10 year workmanship warranty.

Hope this helps? No thanks necessary - I consider it a great privilege to be able to help far more experienced forum members, from whom I've genuinely learnt so much over the years!

P.S. The IOF tariff is truly remarkable BTW - I know households earning £600+ a month with < 30 bifacial panels and a PW3. 

JKenH

Screwdriva said:

The PW3 is typically added on for just over £7K installed (I do my best to pressure the installer to maximize competitiveness for MSE forum members). The 11kWh theoretical maximum discharge rate can be very handy on intelligent Flux, even with a 7kWh discharge limit. There isn't much difference in the price of the AIO and PW3 and the former is about to be replaced by an entirely new generation AIO 2.0 battery inverter, which should have its share of teething issues I'd imagine. Then there's the PW3's Stormwatch, Class leading off grid , outdoor and cold weather performance & an unmatched after sales and safety record. 

The estimated cost above includes a DNO re-application, should you decide to go down this route & a 10 year workmanship warranty.

Hope this helps? No thanks necessary - I consider it a great privilege to be able to help far more experienced forum members, from whom I've genuinely learnt so much over the years!

P.S. The IOF tariff is truly remarkable BTW - I know households earning £600+ a month with < 30 bifacial panels and a PW3. 

Thanks @Screwdriva. Would you be able to suggest a Powerwall installer in my area please - DN21.

Just out of interest what do think to the pricing on the quote I got. You will be more familiar with installation costs and mark up.

Qyburn

Screwdriva said:

P.S. The IOF tariff is truly remarkable BTW - I know households earning £600+ a month with < 30 bifacial panels and a PW3. 

What's that, an overall 34p/kWh?

Screwdriva

Qyburn said:

What's that, an overall 34p/kWh?

Just under 30p per kWh with a South aspect roof. 

Screwdriva

JKenH said:

Thanks @Screwdriva. Would you be able to suggest a Powerwall installer in my area please - DN21.

Just out of interest what do think to the pricing on the quote I got. You will be more familiar with installation costs and mark up.

Will gladly sort this for you.

Solis inverters aren't expensive (~£700) and the Duracells are rebadged Puredrive batteries, which sell for £4.3K for 10kW. So £5K in parts and £300 in labour means the installer earns £500.

In terms of capability, an AC coupled 5kW Solis inverter simply can't compare with a correctly installed PW3, even when it's working right. 

NedS

Screwdriva said:

P.S. The IOF tariff is truly remarkable BTW - I know households earning £600+ a month with < 30 bifacial panels and a PW3. 

Very much so.

If you are a net exporter in summer, then IOF is indeed highly lucrative. I had my PW3 installed in July, and I calculate I'm making almost double what I would have made if I'd stayed on the Cosy tariff with the standard 15p SEG for export. I am able to make enough in summer to completely cover our usage in winter, including heating with an ASHP, so we effectively have no bills. For reference, we earned £228 for export in August with a 7.2kWp south facing array, or were £152 in profit after deducting the cost of our imports for the month, which would have covered the monthly bill in January, the coldest month last winter.

We plan to switch between IOF and Cosy tariffs in summer and winter as we move from being net exporters in summer to importing over winter for the heating.