Solar PV + Battery quotes

cool_techie

Hello forumites,

Help and advice needed please. I have been looking to get Solar PV installed in my current house, which has a fairly large roof and also an independent double garage. Layout picture, provided below.

Following Martyn1981's advice on these threads, I have tried getting installers to quote for the maximum number of panels possible.

Finally, have now received the following quotes from 2 installers (3rd one has now quoted today: 21-Sep)) for a solar PV system, with battery options.

Installer 1: 16 mono panels on the garage and 16 on the house, Ulica 370w panels, iBoost and a battery of 8.2 kWh. There will be an extra inverter to cover the 2 separate panel sites. Cost of £12,200.00 incl. VAT 

Installer 2: 21 x 340 Piemer panels, 6.5 Growatt Smart Battery, iBoost Hot water booster. Cost of £11,700 incl. VAT

EDIT - 21-Sep
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Quote recvd. form 3rd Installer
Installer 3: 30 x 350W panels, 1 x Solaredge Inverter, 30 x Solaredge Optomisers, 2 x 3.5kw Pylontech Battery (7kw) & iBoost. Cost of £10,895 incl. VAT
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I have queried on inverter and panel brand (from installer 1), DNO permissions required etc. and am waiting on a response. I am also awaiting on response from a 3rd installer. Will provide here, once I have the quotes.

Wanted to know, your views on these quotes and also any issues you foresee on the system size, w.r.t. DNO permissions, Inverter efficiency etc. Also, any other point, which needs to be considered. The installer 2, told me to drop the iBoost, since i was getting a battery installed, but I insisted on him getting it included, having seen the benefits at my previous house.

Thanks, CT

Solarchaser

Hi there, id say your first quote is by far the best, as its over 11kw of panels. Plus the battery.

Both batteries are pretty small.... but the reality is that batteries can't quite wash their face as yet, so it will give you a look at what benefit they could bring in time.

I'd be looking to add an iboost or equivalent to your first quote if possible. 

As someone who has quite a few batteries, id say that with my lower kw array than yours. The batteries are filled on any bright day by noon, and then you are exporting, so its better that you can divert to hot water.
So your higher power array will fill the batteries even faster, so more to divert.

In cost per kwh saved, heating a hot water tank with a £3-500 iboost etc is going to do alot better than a battery at £3-500 per kwh.
With the iboost you can sink say 10kwh a day into the hot water tank. But for the same price you can only sink 1 kwh into a battery.

Hexane

Solarchaser said:

In cost per kwh saved, heating a hot water tank with a £3-500 iboost etc is going to do alot better than a battery at £3-500 per kwh.
With the iboost you can sink say 10kwh a day into the hot water tank. But for the same price you can only sink 1 kwh into a battery.

Worth mentioning though that if one still has mains gas for heating hot water, then each kwh put into a battery can potentially have much more value (when coming back out!) than a kwh put into a hot water tank.

And if the installation is going to be on metered export not deemed export, then I struggle to see how an iBoost is worthwhile, since using it to put 1 kwh into your hot water tank (supposedly "saving" you the few pence you might later use to heat that water using mains gas), loses you the similar number of pence that you would've received from exporting that same 1 kwh back to the grid instead.

Solarchaser

Yeah fair points.
I was looking at it from a use as much as you can point of view, but if you are paid for metered, then it makes sense to drop the water heater 

AntonyTewks

I would think on a huge 12kwp system you're going to be pushing out loads to the grid and at most only getting 5p per kWh back. I'd be minded to get slightly less and a bigger battery to make sure you are utilising what you are producing. With a 12kwp array you could fill that battery in half an hour and then the rest goes to the grid for a relative pittance. Have you got an EV? The second one seems a bit better balanced. With diverters I feel.it depends on your motivations. If it's about saving money then gas is dirt cheap (though that should change one day) but if it's about reducing fossil fuel use then theyre great. 
As someone whose had PV post-FIT I don't necessarily feel it's just about getting as many panels as you can (though if you've the budget then great!). I think the key to getting value from them post-FIT is to maximise your self-consumption so the broader package is important - diverters, batteries, EV etc. 

Exiled_Tyke

AntonyTewks said:

I would think on a huge 12kwp system you're going to be pushing out loads to the grid and at most only getting 5p per kWh back. I'd be minded to get slightly less and a bigger battery to make sure you are utilising what you are producing. With a 12kwp array you could fill that battery in half an hour and then the rest goes to the grid for a relative pittance. Have you got an EV? The second one seems a bit better balanced. With diverters I feel.it depends on your motivations. If it's about saving money then gas is dirt cheap (though that should change one day) but if it's about reducing fossil fuel use then theyre great. 
As someone whose had PV post-FIT I don't necessarily feel it's just about getting as many panels as you can (though if you've the budget then great!). I think the key to getting value from them post-FIT is to maximise your self-consumption so the broader package is important - diverters, batteries, EV etc. 

An interesting conundrum.  Batteries are really financially viable yet.  4.8Kw probably isn't enough to get a household from dusk through to dawn (especially if they cook with an electric oven).  I do however like the prospect of a huge system which will reduce the amount imported from the grid in winter.

cool_techie

Thanks everyone for your responses and suggestions. Lots of data points to consider over the next few days/weeks. 12k is a fairly large sum and while return on investment is not the greatest in the post-FiT era, i would want it to be future proofed for some years at least.

@AntonyTewks, we do not have a EV yet, but the way things are moving in the market, may end up with 2 EVs in the next 4-5 years.
Regards, CT

AntonyTewks

cool_techie said:

Thanks everyone for your responses and suggestions. Lots of data points to consider over the next few days/weeks. 12k is a fairly large sum and while return on investment is not the greatest in the post-FiT era, i would want it to be future proofed for some years at least.

@AntonyTewks, we do not have a EV yet, but the way things are moving in the market, may end up with 2 EVs in the next 4-5 years.
Regards, CT

Ah ok, at 12kw you won't be far off charging both at the full 7 then! 

Reed_Richards

You will probably find that the iBoost does not work, or work well, with a battery.  The iBoost finds it difficult to tell if electricity being exported is coming from the solar panels or the battery.  You may think that export cannot come from the battery but the battery will not respond instantly to a change in demand (or the controller does not allow it to).  So if, for example, you have been boiling a kettle with the aid of the battery then when the kettle boils and switches off the battery will temporarily export the electricity it had been using to power the kettle whilst it ramps down to the reduced level of demand.  If the iBoost picks up on this it will turn-on the immersion heater and drain the battery.      

cool_techie

All,
I have today received the quote from a 3rd installer and updated the original post.
Thank you all, for your help and assistance so far!
Regards, CT

Solarchaser

Reed_Richards said:

You will probably find that the iBoost does not work, or work well, with a battery.  The iBoost finds it difficult to tell if electricity being exported is coming from the solar panels or the battery.  You may think that export cannot come from the battery but the battery will not respond instantly to a change in demand (or the controller does not allow it to).  So if, for example, you have been boiling a kettle with the aid of the battery then when the kettle boils and switches off the battery will temporarily export the electricity it had been using to power the kettle whilst it ramps down to the reduced level of demand.  If the iBoost picks up on this it will turn-on the immersion heater and drain the battery.      

With the size of the array vs size of battery I doubt you would notice this in real world.

Because the battery is so small that it will hardly be noticeable,  and you would expect that unless you are charging an ev as well, that the pv power will be charging the battery and running the iboost as well as still exporting.

11kw system is going to be generating 4-5 kw in the middle of an average day, so even on full power, the iboost can only sink 3kw, so the rest would go to battery regardless