Solar panels and battery - any real world reccomendations?

gpuerrilla said:
I welcome this mythical 5p cheap rate you speak of! Over here best I could get was about 9p and that was about two years ago. From the sounds of it, with fresh hikes applied your lucky if you can get below 20p a unit.
Click to expand...
Or go with EDF Go electric 35 - 5hrs at night at 4.5p/kW
 
SBo said:
On the battery break-even calculations have you taken into account the winter months when supply from your panels will be poor, so force charging your batteries at a cheap rate c. 5p KWh overnight and using that during the day versus paying c. 40p KWh?
Click to expand...
I didn't include charging the batteries from the grid at cheap night time rates. In our case it wouldn't make sense to use those variable rates with low cost night time rates and high day rates because in the winter we average around 25-30 kwh per day and can use 50 kwh per day (all our heating and hot water is electric from an ASHP). Even if we had enough battery capacity to hold 30 kwh we'd need a hefty inverter to get enough charge within the 4 hr time period. So we'd end up using lots of electricity on the expensive high rates during the day.
 
I think the main issue with batteries is the cost per kwh stored is just too high. What's the install cost of a 12kwh battery system + inverter? At best around £6000, or quite a bit more if its tesla?
Back of the envelop calcs:
A 12 kwh battery with a 90% DOD = 10.8 kwh, take another ~5% off for AC-DC-AC conversion and you've got ~10 kwh/day to play with which at current standard fixed rate tariff electricity prices (~20p/kwh) versus night time low rates tariffs (e.g. 7.5p), provides potential to save 10kwh * (20-7.5) = is only £1.25 saving per day, or £1.25*365 = £456/yr
Life span of battery + inverter ~10 years.
 
This thread is brilliant for people looking into solar and the cost of harvesting energy from the sun. But can people stop quoting payback and how long it would take.
The payback is harvesting your own energy and not paying for it, no matter how much electric prices raise or fall.

we dont buy gas boilers and wonder whats the payback or electric cars…..so why worry about solar payback. Just buy it, use it and enjoy harvesting that free energy
 
For most people it is a financial decision solely to save money, a car is not, its usually a means of transport. So ROI on investment for solar panels and batteries is a very important factor for most, I for one find it very interesting.

We paid £6600 for our panels back in December 2015, we have earned/saved £5600, so £1k off ROI :D
 
Ron-ski said:
For most people it is a financial decision solely to save money, a car is not, its usually a means of transport. So ROI on investment for solar panels and batteries is a very important factor for most, I for one find it very interesting.

We paid £6600 for our panels back in December 2015, we have earned/saved £5600, so £1k off ROI :D
Click to expand...

Pure profit after that, in a manner of speaking.
 
Ron-ski said:
For most people it is a financial decision solely to save money, a car is not, its usually a means of transport. So ROI on investment for solar panels and batteries is a very important factor for most, I for one find it very interesting.
Click to expand...

I half-convinced a solar skeptic (last year) that prices would rise, and payback would be quicker that anticipated, this was after he saw the setup I had sorted for myself, and though that spending the best part of £10k was madness. He was just ordering a new car at the time, which is standard thing he does every 2-3 years so I was talking to him about the deprecation side of things, as well as the totally fleecing you get for 'extras'.
I suggested if you are only keeping a car for 2-3 years why not buy the next model/spec down or lose some of the toys, and save £5k+ and take that off the solar install cost. Obviously some of the value of the used vehicle would have been in the total spec/extras so a reduced trade-in or sale price but no where near the amount spent. In the end he ignored the suggestion, 'cause gotta have that 360 camera and heated rear seats that are never sat in. however that isn't where it ends.
Due to parts shortages, his new car was delayed and unless he reduced the spec he'd end up waiting possibly up to six months longer. So he decided to get a model that was a cancelled order almost to his spec that would be arriving much sooner, saving him about £3.8k. Obviously after he tells me this I laugh, and he wants to look into solar again, told him good luck getting on the wait list, all the prices have gone up and the ROI will be even longer and now you are paying even more for your bills.

However it got me thinking, I wonder how many people could make a short term sacrifice for a longer term gain? The sort of folk I am on about are the guy above, spends £50k on a car for 2-3 years use losing a huge chunk in the process, but won't spend 10k on something that might last 25 years+ - to me the short sightedness is ridiculous, or maybe it is just lack of knowledge and education in how things work. Perhaps they were put off by the old solar schemes rent-a-roof etc. and they think the prices are high till for what you can get.
 
Its basically endemic, expressed best with politicians and their short termism. Only looking into the win votes movement when it matters to them, we could have invested into heaps of better technology and incentives 20+ years ago. So your fella you described above is this short term thinker that decides to worry about the reactive stuff later down the line until, like today it hits him in the face then all of a sudden he's 'interested' in solar again! :cry:
 
Ron-ski said:
For most people it is a financial decision solely to save money, a car is not, its usually a means of transport. So ROI on investment for solar panels and batteries is a very important factor for most, I for one find it very interesting.

We paid £6600 for our panels back in December 2015, we have earned/saved £5600, so £1k off ROI :D
Click to expand...
I see you chose to comment on the car, but not the boiler………..like i said this thread is very good, loads of info, but for me the payback is “im paying for my energy, not paying to buy someone elses” for me thats the biggest return on investment and not how long it takes me to break even
 
@Welshman a new boiler is similar to solar, it will save money in the long run, but ROI will be longer. A new car is an expense, very few gain money, most depreciate as soon as you drive them off a forecourt. My car is a 2009 VW, paid for the day I bought in 2013, and worth far less than what I paid for, and it's earned me nothing, although I suppose you could argue it's saved me money on using public transport.Its simply not a suitable comparison, on the other hand my solar investment will have paid for itself in about nine months time, then free electric and I still get the FITS payments :D
 
SBo said:
On the battery break-even calculations have you taken into account the winter months when supply from your panels will be poor, so force charging your batteries at a cheap rate c. 5p KWh overnight and using that during the day versus paying c. 40p KWh?
Click to expand...

Yes I built it into the ROI but the numbers at the time were somewhat a guesstimate given I've no first hand experience of how it would work in reality. I've had another look and would probably revise the numbers up now slightly.
On my current tariff (31p day, 7.5p night) it could in theory translate to a circa £2.2/day energy saving for a 12KW battery for probably 5-6 months of the year, so around a £500/year saving? Add in the couple of KW saving the battery would give me in the summer months and it might push the saving per year to around £600 for a 12KW system. Assuming £5k-£6k install payback could be as low as 8 years, but still likely closer to 9/10.
 
Welshman said:
This thread is brilliant for people looking into solar and the cost of harvesting energy from the sun. But can people stop quoting payback and how long it would take.
The payback is harvesting your own energy and not paying for it, no matter how much electric prices raise or fall.

we dont buy gas boilers and wonder whats the payback or electric cars…..so why worry about solar payback. Just buy it, use it and enjoy harvesting that free energy
Click to expand...
With those I've spoken to your approach seems to be in the minority. Everyone that's approached me after seeing the install has wanted to know how much it cost and how much it'll save me. There's in reality very little benefit other than cost of on-site microgeneration versus purchasing electric from the grid.

For me it was certainly 90% driven by the financial investment. I want my savings to work hard for me and investing in solar PV was an obvious choice. I couldn't care less whether I'm buying my electric from the grid or generating it myself, I just want the best value option for me. Either way the energy I purchase/produce is from carbon neutral sources so there's also no environmental benefit as such.

I wouldn't class a gas boiler in the same category for most people. For the majority of houses with gas fired central heating / hot water it's simply a case of they already have one and if it breaks they need a new one to heat their home/water. It's a non-returning investment replacing an end of life asset. I am however now considering whether I'm better off using the electric immersion to heat my hot water even when there's insufficient solar energy (e.g. in winter). I'm paying over 7p/kw for gas that's probably only 80% efficient, versus heating my hot water overnight for 7.5p/kw at nearly 100% efficiency. Gas is likely to fall further out of favour due to the carbon intensive nature of using it so I can see the cost continuing to rise.

For a car it absolutely is a numbers game for many. There's of course the big overlay of it being a status symbol but it usually comes down to what's the best car I can get for my budget and what's the monthly cost, MPG etc. I directly tied in my car purchase numbers with the solar PV install, it seemed utterly mad spending £56k on a car and not paying the extra £7k to be able to charge it using solar.
 
Last edited:
Abyss said:
With those I've spoken to your approach seems to be in the minority. Everyone that's approached me after seeing the install has wanted to know how much it cost and how much it'll save me. There's in reality very little benefit other than cost of on-site microgeneration versus purchasing electric from the grid.

For me it was certainly 90% driven by the financial investment. I want my savings to work hard for me and investing in solar PV was an obvious choice. I couldn't care less whether I'm buying my electric from the grid or generating it myself, I just want the best value option for me. Either way the energy I purchase/produce is from carbon neutral sources so there's also no environmental benefit as such.

I wouldn't class a gas boiler in the same category for most people. For the majority of houses with gas fired central heating / hot water it's simply a case of they already have one and if it breaks they need a new one to heat their home/water. It's a non-returning investment replacing an end of life asset. I am however now considering whether I'm better off using the electric immersion to heat my hot water even when there's insufficient solar energy (e.g. in winter). I'm paying over 7p/kw for gas that's probably only 80% efficient, versus heating my hot water overnight for 7.5p/kw at nearly 100% efficiency. Gas is likely to fall further out of favour due to the carbon intensive nature of using it so I can see the cost continuing to rise.

For a car it absolutely is a numbers game for many. There's of course the big overlay of it being a status symbol but it usually comes down to what's the best car I can get for my budget and what's the monthly cost, MPG etc. I directly tied in my car purchase numbers with the solar PV install, it seemed utterly mad spending £56k on a car and not paying the extra £7k to be able to charge it using solar.
Click to expand...

Using cheap rate electric to heat hot water is now right on the cusp as you say, it was certainly not cost effective until recently.
One of the key factors right now is the storage efficiency of your tank vs the time you get cheap electric. If you tank is relatively new check out its stats on daily energy loss. Maybe use a different term but it should give you a number around the 2-4kwh mark which it would cost you to keep it at that temp.
If that number is really high then right now your probably better on gas, just. The temperature differential is the key.
Once gas goes up again, assuming it does later this year, if its more than 10% or so you would probably find it cheaper to heat with elec.

Its a scary prospect and IMO highlights just how much energy has gone up. Until last year or so, heating water with electric was really expensive in comparison to gas.
 
For those comparing, we are paying £9,900 in South Bucks for:

15 x Hyundai 410w Solar Panel + 15 Tigo Optimiser
LUX 5kw Hybrid Inverter + 7.2kw Battery [2x Pylontech US3000C]
Emlite Generation Meter
Electrical Equipment + Cabling + MC4 Connectors
Roof Mounting Kit + Scaffold
Bird Protection Meshing
Installation & Commissioning of Solar PV + Battery
Register Installation with HiES & MCS

The panels are split over 4 aspects; east, south 1, south 2 and west so will need a lot of scaffold.

Being installed at the end of May.
 
Good price that, good to see some reasonable quotes. Had to bite my tongue at a colleague yesterday, had agreed to purchase pretty much same set up as yours @SBo but for close to £15k, had given him a load of advise and how much to expect to pay.
 
Last edited:
Octopus Agile pricing is starting to look reasonable again. You can make good money at peak rates exporting your excess, even applies in the summer as the peak is still the peak. Average import pricing for the last couple of days has been sub 20ppkWh for my region, with lows in the 6p range. :)
 
You must log in or register to reply here.
Back
Top Bottom