Solar PV target price

AntonyTewks

Ah ok that's interesting. My understanding of solar and FIT grows further.
I estimated we only spend about £60 ish a year on hot water. Gas is ridiculously cheap. I feel our tank will be due replacement soon anyway so looking to do it as part of replacement cycle as with the boiler (though having bought that 3 years ago it has some way to go!) 
The government really should be supporting solar more, especially west facing arrays to help green the dinner time peak. I know wind is taking a lot of the slack but we're going to need a very diverse energy mix to go zero carbon.
I'd wondered about batteries but agree they seem way too expensive. We got a Renault Zoe last year and it felt silly to get an expensive house battery with long payback when we could just put the excess solar into the car battery. That said at the mo the Zappi seems an expensive upgrade so thinking of just getting a granny cable to charge from the mains at a slower rate so we mostly use the solar.

pinnks

Interesting discussion.  I have an immerSUN diverter and know for a fact that I save significantly by having it.  OK, so I am on the FiT with deemed export but I also know that I save between £70 and £80 in gas over the summer when my boiler is turned off (I have records going back to 2009, well before I got my PV to compare consumption then and now) and over the remainder of the year I estimate that the diverter contributes to a further saving of perhaps £20, so around £100 per annum.   

A key factor which many seem to forget when comparing leccy and gas prices to compute potential savings from a diverter is the inefficiency of using the boiler only for hot water.  Not only is the boiler less efficient in itself but you also have to heat the 10 to 20 round-trip metres of probably un-lagged copper pipe in addition to the water in the tank and that heat is just heating up and already hot house!

But diverters are like marmite and you won't convince either side of the argument to change their views, whether they are financial or environments  

Martyn1981

AntonyTewks said:

Ah ok that's interesting. My understanding of solar and FIT grows further.
I estimated we only spend about £60 ish a year on hot water. Gas is ridiculously cheap. I feel our tank will be due replacement soon anyway so looking to do it as part of replacement cycle as with the boiler (though having bought that 3 years ago it has some way to go!) 
The government really should be supporting solar more, especially west facing arrays to help green the dinner time peak. I know wind is taking a lot of the slack but we're going to need a very diverse energy mix to go zero carbon.
I'd wondered about batteries but agree they seem way too expensive. We got a Renault Zoe last year and it felt silly to get an expensive house battery with long payback when we could just put the excess solar into the car battery. That said at the mo the Zappi seems an expensive upgrade so thinking of just getting a granny cable to charge from the mains at a slower rate so we mostly use the solar.

This is our first Spring & Summer with a BEV, and obviously C19 is mucking things up, but it does seem possible to do most charging with a granny charger and MK1 eyeball (plus weather forecast) from PV. Our cable is 2.2kW, and our PV will exceed that, on a good day, from around 9am to 4pm.

Have to agree with pinnks about the DHW. During the hotter months, all heat loss from the boiler and pipework is wasted energy (in the heating months it can be seen as simply helping with the heating). So you probably only get about 50% efficiency from the boiler. Environmentally it's probably breakeven as 2kWh of gas will be burnt to replace the 1kWh of leccy not exported, but going forward, if the Gov takes it's boot off the neck of the PV industry, we will probably see greater excess generation during mid day, and one solution to this is to find ways to store it or ...... time shift demand ..... such as DHW.

AntonyTewks

That's interesting. I'm hoping for the same when we get PV or at least a decent contribution to car charging requirements. I can get a granny cable for less than £200 Vs getting on for £1.5k for a Zappi. I'll look at Zappi one day when we get another EV maybe but in the short term the cost doesn't really stack up when we already have a 7kw charger just a year old. 
I'm very intrigued by the mixergy tank, the insulation is very high (less than 1kwh heat loss in 24 hours so alike a battery) and very programmable so I'm hoping that would make the most of the solar and reduce losses. Not immediately on the agenda for us tho. Panels first.....

EricMears

AntonyTewks said:

I can get a granny cable for less than £200 Vs getting on for £1.5k for a Zappi. 

The 'granny lead' supplied with my car was a 10A (only) version.  For £170, I bought a lead that is adjustable from 6A to 13A  frim eBay.  That particular one is no longer listed but looks very similar to https://www.ebay.co.uk/itm/Mode-2-LCD-EV-Type-2-Portable-Charger-6-13A-250V-5M-UK-3-pin-plug-IP67/352930251507?hash=item522c4842f3:g:X7oAAOSwxbpeezEn

6A is very useful when you've only got 1.5kW 'spare' ,  intermediate values if there's a bit more sun or 13A ideal when charging elsewhere

Petriix

I managed to get a zappi 1 early last year for £215 cost to myself (with the rest a result of a very cheap quote from a new company, the £500 grant and a contribution from the EV taxi company I was driving for). Sadly I can't afford an EV of my own at the moment.

Solarchaser

I feel I'm of a similar mind to you Antony.
I added an Ev 18 months ago, and I think have "paid" for around 1k miles of the 8k miles its done since then.... charging in the winter.

I have the granny charger,  I've hovered on getting a zappi a few times, but i don't really need it.
If I needed a quick charge, there's 50kw chargers around 2 miles away.

I put extra solar on my garage, and went with batteries last year, and increased them this year.
About 2 years ago we did the kitchen,  and fitted induction hobs, but kept the gas oven.
2 months ago, we went to electric oven.

Next year I am going hot water tank, to replace the two electric showers and stop using gas for heating water.

Ideally the year after I'll add another tank (if there's still excess solar or the wind generation is consistent enough to make overnight charging feasable) for the central heating,  with the plan to do away with gas altogether. 

I'm not convinced on mixergy vs thermal store, as ideally id like to be able to store a couple of days worth of hot water, and the mixergy tanks are pretty small.

JKenH

I have a Zappi. With the OLEV grant it cost me about £400 more than a basic charger. It will only be useful to me about 8 months of the year during which time I might do 5000 miles (nearly all home charging). If it does a perfect job it will displace about 1500 kWh of E7 charging (about £135) so will pay for itself in about 3 years. I could have gone for a basic smart charger for overnight E7 charging and on perfectly sunny days I could use the granny charger and risk a few hours charging at full daytime rate (14p) when the kettle, washing machine or oven draw power. So maybe I am using man maths to justify the Zappi but I like the hub and app that come with it which provides me with much more responsive monitoring than I previously had from my Solar IBoost Buddy. What I can’t put a value on, though, is the satisfaction of knowing I am using surplus (and only the surplus) PV to provide free motoring.

I do get good value from my IBoost though which after 2 years use has diverted  2900 kWh to my hot water tank displacing £261 of E7. I don’t have gas, and oil would only heat (not very efficiently) one of the two hot water cylinders. I would point out however that overnight there is heat loss from the cylinders (at least 2kwh per night) compared to heating on E7 at say 6am - 7am so the real saving is nearer £200 over 2 years.

Solarchaser

Tbh Ken, yeah i think you are using man maths to justify it, but hey, what's wrong with that?
For me using granny charger, I don't really worry about clouds etc because of my home batteries will kick in to cover the granny charger in that scenario.

Perhaps if my leaf would take 6.6kw id be more interested,  but as it only takes 3.3kw and the granny is somewhere around 2.3kw, I can't really justify it.

I've still ran the 10mm t&e and some cat 5 to where it will sit though... so haven't completely ruled it out.

AntonyTewks

Back on topic. Any thoughts on premium panels and whether the premium is worth it?
I've had a company quote for LG Panels, they come with 25 year manufacture warranty and just shy of 21% efficiency. They also guarantee performance at 90% after 25 years. Fair chunk more but sound very good and the guarantees around reliability are reassuring. 
Also, we had planned on using our West roof but been advised against it because it's about a 50deg steep pitch also about 25deg slightly to the north so more like WNW. So I'm wavering on using that now
Without it though we may only be able to get 3.6kwp across SE and SW - is that still a decent enough array to help with car charging etc as well as normal living?
Thoughts appreciated as this is proving a really rather tricky decision!