Sense check Eon PV and battery quotation please

k6chris

Just had a series of quotes from Eon, and very impressed with their service so far. We have had a quote, details below, and just want to see if anything leaps out, or if there are other questions I should ask?  Not looking for the cheapest option, just keen to avoid buying a pup! Quote is based on:

• 14 x T1 405 W panels giving a system size of 5.67 kW,
• GivEnergy Hybrid Gen3 inv. with 5.2 kWh battery (4.2 kWh usable)
• "free" Vestle 4 EV Charger (the 7.5kw model).
• All Installation / registration costs
• £13,357.29

It's a perfect shade free south facing roof, and estimated "benefits" in year 1 is £1,391 based on our usage. There is a 3 year 0% finance offer too. 

Thoughts and feedback please.

Thanks

Screwdriva

In my experience, companies like EON tend to over charge while supplying okay kit. For perspective, a quote seen v recently:

14 X SHARP 410W Black panels 
14 X SolarEdge Optimizers
  1 X SolarEdge 5kW Inverter (20 year warranty i.e. twice that of GivEnergy)
  1 X Myenergi Zappi Solar PV integrated charger (The Vestel is not PV integrated to the best of my knowledge)

~£8450 installed. G99 included.

Pylontech batteries adds another ~£3K to the total but I wouldn't recommend any battery unless your household consumption is significantly higher than 4000 kWh per annum. They no longer make much financial sense unless you run a heat pump/ experience blackouts/ have really high consumption/ drive that EV a lot. 

Regardless, the above spec offers top tier, non-Chinese panel and inverter brands + modular storage for ~£1500 lower than the EON quote. 

k6chris

Screwdriva said:

 I wouldn't recommend any battery unless your household consumption is significantly higher than 4000 kWh per annum.

That's interesting.  We use almost exactly 4,000 kWh pa, without EV charging (we don't currently have one). The Eon quote for a 14 panel non-battery solution is:

• 14 x 405 W panels giving a system size of 5.67 kW,
• Solis 1-phase inverter
• £8,987.95

This does not include the "free" ev plug point, not sure how easy it would be to add one to the above?

Screwdriva

Would recommend skipping the battery for now as you would likely never recover the cost based on your current usage. Instead, I'd suggest selling your excess Solar PV via Octopus Flux, effectively using the grid as your "battery". 

Sorry to share, the 2nd quote shared above is worse - Chinese brands and no PV enabled EV charger.

A Zappi is arguably the best Solar integrated EV charger on the market and costs ~£1500 installed these days - you can always add one later and just subtract that amount from the quote shared above for a total cost of £6950 installed for far superior kit. 

k6chris

Screwdriva said:

A Zappi is arguably the best Solar integrated EV charger on the market and costs ~£1500 installed these days -

Thanks (again!)  One more dumb question, is it possible for an EV charger to only charge when it using power from your panels / battery?  i.e. a setting of "don't charge from the grid unless I tell you to."   Thanks!

Exiled_Tyke

Unless I've got this very wrong the estimated benefits of £1391 implies self-use of 4,200 kWh a year (at 33p per unit and if electricity prices fall then much more self use is needed to get to this figure).  This quite simply is not possible with the system size and your currently quoted current useage.  It implies using a very high percentage of the electricity produced and it meeting 100% of your current needs.   (Of course this benefit could be based on some self use and selling some back to Eon but  I can't see this being realistic either).

If I got this right and they are making ridiculous claims then I'm afraid all trust is gone and I would stay well away.

k6chris

Exiled_Tyke said:

Unless I've got this very wrong the estimated benefits of £1391 implies self-use of 4,200 kWh a year (at 33p per unit and if electricity prices fall then much more self use is needed to get to this figure).  This quite simply is not possible with the system size and your currently quoted current useage.  It implies using a very high percentage of the electricity produced and it meeting 100% of your current needs.   (Of course this benefit could be based on some self use and selling some back to Eon but  I can't see this being realistic either).

Thanks.  Currently we use around 4,000 kWh per year, not including EV charging. Eon calculation is based on:

"14 x 405w panels with 5.2 kw (4.2kw usable) battery. This is a system size of 5.67 kw which will generate around 5007 kwh a year. We estimate if you used 58% of the generated electricity and sold back the other 42% (at 16.5p per kwh to Eon using the SEG Tariff) you would save a minimum of £1391 a year."

This implies using 2,500 kWh of PV generated electricity, either direct from panels or stored in battery, i.e. around 63% of all our existing electricity requirement.  Excess being sold back.  Is this realistic??

Screwdriva

k6chris said:

This implies using 2,500 kWh of PV generated electricity, either direct from panels or stored in battery, i.e. around 63% of all our existing electricity requirement.  Excess being sold back.  Is this realistic??

In our PV only household, we sell 67% for an average rate of ~22p now and consume around 33% at an average rate of ~26p, all via Octopus Flux. We generate roughly 3.8mW per annum from our 10 panel 4kW system despite 3 aspects and chimney shading. That works out to just under £900 per annum at the above tariffs. 

A wise forum member shared this post about using the grid as your battery for relatively low consumption households that you may find to be a valid perspective:

Exiled_Tyke

I'm still not sure whether it's realisitic or optimistic.  

You can check the generation estimate at:  https://re.jrc.ec.europa.eu/pvg_tools/en/#api_5.2

You will need to be quite clever in your power consumption to achieve the self-use stated. A lot depends on whether you around during the day to make use of the excess and can time high energy appliances accordingly. And then not running too many appliances at once or you'll start drawing from the grid.  (This is bearing in mind that the battery will only hold a small fraction of production on a good Summer's day (when you could get upwards of 25kWh).  (Note my consumption is way below yours but in the recent dismal summer weather my 6.3kWh battery has run out in the evening forcing me back onto peak time electricity).

Ideally you should also consider expectations of future electricity prices.  Difficult I know but if they come down (which many project to be the case) then these savings will dramatically reduce. 

Finally don't forget that the batteries are not 100% effecient and 'round trip loses' will be signficant. 

On balance I think it's still optimistic.

Solarchaser

How much you will self consume depends pretty heavily on 1 thing.
Your EV and its use.
If its mostly at home during the day, and you do say 10k miles a year in it then you could argue 2500kwh on ev charging,  and so you will meet their consumption target with ease.

However if like most folk your ev is used for commuting, then the solar will only be a benefit for charging your ev at the weekend, so that 2500kwh only 2/7ths of it will be from solar.

At 4mwh a year, you are a faillrly low electric user, so really I'd struggle to justify batteries.

You will probably find you use maybe 1200kwh in the 6 brightest months, and thats when you solar will produce most of its electricity. 
But you will use the other 2800kwh in the darker months when solar isn't so good at producing.

Zappi from myenergi will do solar charging, not many other options will

Screwdriva

Solarchaser said:

Zappi from myenergi will do solar charging, not many other options will

https://corporate.solaredge.com/en/this-is-solaredge/news-and-media/press-releases/new-bi-directional-dc-coupled-electric-vehicle-charger

Only for SolarEdge inverters sadly but the prospect of a commercially available plug n play bi directional EV charger for compatible EVs is compelling.