Solar Panels - Energy Saving

Exiled_Tyke

Go to http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php?lang=en&map=europe and provide your location to estimate generation. I would guess you are looking at a 4Kw system (16 X 250w panels).

You will most definitely still need to draw from the grid as winter generation will provide very little. Whether or not you can use all of the summer generation is another moot point - suffice to say that it's highly unlikely you can store or use all at the energy - but that does depend on your useage. My average useage across the year is about 8Kw per day but in Summer my modest system can produce over twice that. So even with decent size batteries a run of a few bright days would still see me exporting a fair amount to the grid.

If you find a single fault in the figures they have provided then seriously - walk away - the trust has been broken. Unless you have the proof these numbers still look stupidly optimistic

Martyn1981

Hello Kevin, warning, this is going to get complicated and confusing.

10k for a 4kWp system and battery might not be too much, but and that's a very big BUT, it'll depend on how big the battery is, what type and technology it is and also because batteries are currently very expensive.

Hopefully battery costs will fall significantly in the next 5 years, but at the moment you'd be paying too much, even if it's a fair price.

As to how much generation you could use, that's even more complicated as it will depend on how much leccy you use, when you generate your own, and how much of it you can store and use.

For instance, in the summer months I might generate 30kWh on a very good day, thus reducing my import down from 7kWh to 2kWh, and exporting 25kWh's. regardless of how big my battery pack is, if I only use it for those 'missing' 2kWh's then I can only put another 2kWh back in, so 23kWhs will still get exported..

In the winter when I use more leccy, get less from PV directly, I could store more and make use of it, but I don't generate enough so I'd only have 1 or 2kWh of export each day that could go into the batts.

Happy to chat and explain all of this, as it's a lot to get your head around. Just keep asking questions till it makes more sense.

Mart.

Kevinwebster

Thanks for the comments the site indicated government fully funded solar panels which gave the link w.green-incentives.org.uk to see if you were eligible so I filled it in and then got the phone call. I was confused by the charge, but if I can make the savings suggest it could still be worth will.

tunnel

Martyn1981 wrote: »

and you'll need to aim for a price of around £5k.

Flippin eck Mart, get with the times, closer to £4k for just a solar system

Martyn1981 wrote: »

10k for a 4kWp system and battery might not be too much,.

Flippin eck Mart, get with the times, closer to £8.5k for a solar system and storage


In fact my local installer offers a system for £4k and now has a 5kWh storage add-on(Growatt) for another £3350....so less than £7.5k making the OP's quote rather on the expensive side.

ASavvyBuyer

Kevinwebster wrote: »

Thanks for the comments the site indicated government fully funded solar panels which gave the link w.green-incentives.org.uk to see if you were eligible so I filled it in and then got the phone call. I was confused by the charge, but if I can make the savings suggest it could still be worth will.

It is very unlikely that you will make the savings suggested and the system you decribed is very overpriced. You should get quotes from at least 3 different companies, preferably more before you make a decision.
Also, the economic return for having battery storage is very poor at the moment. For example, the savings are likely to take over 20 years to cover the cost of the batteries, but they are only likely to last 10 years before they need replacing.

Martyn1981

Kevinwebster wrote: »

Thanks for the comments the site indicated government fully funded solar panels which gave the link w.green-incentives.org.uk to see if you were eligible so I filled it in and then got the phone call. I was confused by the charge, but if I can make the savings suggest it could still be worth will.

Hiya Kevin, in short, you won't get those savings.
A lot of your generation in the BST months will still be exported.
If you are going to use finance then what is already tight, will become impossible.
Battery costs could/should fall faster in the next 5 years than you'll be saving (in additional leccy savings), in effect you'd save more money waiting than installing a battery.

The numbers from Tunnel are very promising, so your best bet now would be to look at installing a PV system only, if you can get a good price, but consider and research battery storage so that it can be added later on.

You never know, we may even see some sort of incentive scheme for batts, but given recent moves by this govt I doubt it.

For the future, you might want to consider a battery friendly inverter that will allow a battery pack to be added (plugged straight in to the inverter/PV system (DC side)) later on, such as models from Growatt, Nedap, SMA, SolarEdge etc. Or a battery that is installed on the AC side (after the PV system, just linked to the house). The AC batt will have slightly more system losses, but could be installed anytime without concern to the inverter.

Once you have PV, you can keep records, comparing pre PV consumption to post PV consumption, daily generation to get a feel for how it fluctuates each day, and varies each month. Armed with this info, you'll have a better idea of how much you could store, and how much extra import you could save, and thus the annual savings from the battery system (separate to the PV system savings).

Mart.

Martyn1981

Kevinwebster wrote: »

Thanks for the comments the site indicated government fully funded solar panels which gave the link w.green-incentives.org.uk to see if you were eligible so I filled it in and then got the phone call. I was confused by the charge, but if I can make the savings suggest it could still be worth will.

For starters, have a play with PVGIS there's a walkthrough in section 5 of the PV FAQs. How much do you expect to generate?

What is your annual consumption? Is there anyone home during the day to make better use of generation?

Mart.

N9eav

Cost of finance needs to be considered too. I bought a package solar system and although the figures seemed to work out cost neutral, the finance was costing 9.9%. (10 years) I soon changed it to a Tesco loan and saved 3 years payments.


Now after 1 year on a 4 KW South West facing system , I made just over 4000 kw (13.6p Tariff) and I saved 25% on my previous electricity bill (high user). I came out cost neutral. The winter was pretty bad too, so maybe it could be better and I will make a small profit this year.

Martyn1981

Martyn1981 wrote: »

Do you think a 450kWh cap makes sense, reflects typical import savings?

Well, where to start.

I've had a nice chat with the EST who stand by the numbers, citing government research. They say the average saving is 450kWh.

I pointed out that that's just baseload, they said baseload is 81W, I countered with what about central heating pumps more likely to be running during the day, and fridges/freezers warmer in the day etc, but they were unmoved.

So 81W x 10hr average per day (fair?) x 365 days = 295kWh that can't really be avoided no matter how hard you try. Then even for a house empty during the day, you have summer evening use and weekends when folk are home and consuming/saving more.

So 450kWh is an average of 295kWh up to XXXXkWh.

I pointed out that logically I was struggling with this average since my reduction of about 1,400kWh would need about 3 people on zero savings to average out. Thinking about it, it would take 6 households on 295kWh to balance me out.

I also added that those I chat with on MSE or renewables forums, with PV, seem to have reduced consumption far more, but they countered (quite cleverly I feel) that such people are environmentally or financially motivated to do better than the average person. I mentioned that I'm both environmentally and financially motivated, but don't really try hard at all, it just does what it says on the tin.

Does this sound fishy to anyone?

Mart.

pinnks

For what it's worth, I have been able to monitor import, export, diverted, generated and total non-diverted household use for a year now with the immerSUN monitoring gizmo.

I popped this thread on the board the other day. https://forums.moneysavingexpert.com/discussion/5471656

If I look at imported v total non-diverted use I get the amount of own consumption of what I generated. My system is 5,250Wp, so will generate more on cloudy days than a 4kWp system to cover base load, but will not necessarily produce much more on a good day in summer than a well-positioned south-facing system on a 30 degree roof - but then most of that would be exported anyway.

So, in the year to May 2016, I reduced my import by 1,673kWh, or about £175 and that is after three years on honing my "life in series" skills to maximise own consumption, especially of those high-power devices like washing machine, dishwasher etc.

I doubt a 4kWp system would achieve that for the average household, so £120-£150 might be reasonable to work from if you are prepared to switch from living in parallel to living in series...

Just read Mart's comment again about base load. I appreciate that we have 3 fridgefreezers but we also turn off those brick-on-a-string devices like network switch, TV amps and the like when not in use. Our base load is about 300W. I know this because I can see the hour-by-hour over night or when we are on holiday with the house on tick-over and it averages out at 300W summer or winter.