Solar PV – Frequently Asked Questions and Answers

EricMears

coolcol1 wrote: »

Income has 3 components:
1. Feed in tariff (FiT) @ 14.9p/kWh = £536
2. Export 50% deemed @ 4.64p/kWh = £84
3. Leccy savings perhaps £80 to £160 = £120
Total £740
now could you explain these 1,2,3 please.
1 is rate of electric put back to the grid when im out?
3 savings when using the electric against my bill by daytime use?
2..no idea
Cheers

1. This payment is for generating electricity - regardless of what you choose to do with it.
3. Exactly that.

2. In theory, it's a payment for the electricity you generate but don't use. However, very few people have an export meter so in practice it is assumed that 50% of generation would have been exported and payment made accordingly.

Utseya123

Wow! This is like a handbook on solar PV. You have made my day. Can look this up at leisure and implement as I go along.

Mabsabrabcab

Apologies if this has been answered elsewhere, but I can't find it.

I installed solar panels in May last year and I am currently paid at 15.44p for the FIT and 4.64p for the Export tarrif.

All of the information I've read about FIT payments says that they increase in line with inflation, but I have never seen anything that tells me how to find out what the new rate will be or when the increase occurs. Does this happen annually on the anniversary of buying the panels, or at a fixed date annually eg 5th April? Where can I find the new rate at which I will be paid?

tunnel

Mabsabrabcab wrote: »

Apologies if this has been answered elsewhere, but I can't find it.

I installed solar panels in May last year and I am currently paid at 15.44p for the FIT and 4.64p for the Export tarrif.

All of the information I've read about FIT payments says that they increase in line with inflation, but I have never seen anything that tells me how to find out what the new rate will be or when the increase occurs. Does this happen annually on the anniversary of buying the panels, or at a fixed date annually eg 5th April? Where can I find the new rate at which I will be paid?

The increase is linked to the RPI for December and will take effect annually from 1/4..HTH


rate of increase should be able to view sometime later this month, Novembers was 2.6% but with the increase in energy bills could be a little higher for december

Mabsabrabcab

tunnel wrote: »

The increase is linked to the RPI for December and will take effect annually from 1/4..HTH


rate of increase should be able to view sometime later this month, Novembers was 2.6% but with the increase in energy bills could be a little higher for december

That's great, thanks for the quick answer.

khris210

Perhaps I can put in my twopennorth? This is purely financial, no reference to green issues. Fill in your figures for the following questions.
1. Cost of installation.(say £7000 for a 4 kW system)
2. kWh generated by installation. (This is the figure in the quote by the company. An example (real life) would be 3500 for a 4 kW install. I know, I know, but it's a start. My own install exceeded their quote. No, really!)
3. Amount of FIT (both sorts added together eg 17.22p)
4. Multiply together (example 3500 x 17.22p = £602.70)
5. MINUS the interest lost that you would have been earning from your capital had you not spent it on the panels. (In my experience, NO salesman will factor this in!) example £7000 x 3.25%= £227.50 (5 year fixed rate. You are investing for ever, you can't rely on getting your money back if you sell your house)
6. Add the price for the electricity that the installation has saved you. This is difficult to estimate, it will be different for every user, but for the sake of argument say its 50% of the average consumption of 3300 kW which would be say 1850 x 12 p = £222.00
7. The sum is £602.70 minus £227.50 plus £222.00. The resulting figure is your true return on your £7000. And it is £597.20.
8. In this example you must decide whether you are prepared to lose £7000 for ever, in order to improve your return from £227.50 to £597.20. That is from 3.25% to 8.5%. But that's just today.
9. Remember, who knows what the correlation between electricity prices, inflation and bank rate (therefore savings rates) will be in the future.
10. You must fill in your own figures, these are just examples.

Cardew

khris210 wrote: »

Perhaps I can put in my twopennorth? This is purely financial, no reference to green issues. Fill in your figures for the following questions.
1. Cost of installation.(say £7000 for a 4 kW system)
2. kWh generated by installation. (This is the figure in the quote by the company. An example (real life) would be 3500 for a 4 kW install. I know, I know, but it's a start. My own install exceeded their quote. No, really!)
3. Amount of FIT (both sorts added together eg 17.22p)
4. Multiply together (example 3500 x 17.22p = £602.70)
5. MINUS the interest lost that you would have been earning from your capital had you not spent it on the panels. (In my experience, NO salesman will factor this in!) example £7000 x 3.25%= £227.50 (5 year fixed rate. You are investing for ever, you can't rely on getting your money back if you sell your house)
6. Add the price for the electricity that the installation has saved you. This is difficult to estimate, it will be different for every user, but for the sake of argument say its7. The sum is £602.70 minus £227.50 plus £222.00. The resulting figure is your true return on your £7000. And it is £597.20.
8. In this example you must decide whether you are prepared to 50% of the average consumption of 3300 kW which would be say 1850 x 12 p = £222.00
lose £7000 for ever, in order to improve your return from £227.50 to £597.20. That is from 3.25% to 8.5%. But that's just today.
9. Remember, who knows what the correlation between electricity prices, inflation and bank rate (therefore savings rates) will be in the future.
10. You must fill in your own figures, these are just examples.

Good post; however a couple of observations on the above figures.

1. Shouldn't the FIT figure be 16.76p/kWh? (14.38p plus 50% of 4.77p)

2. You are using an interest rate of 3.25%, however surely most of us will pay at least 20% tax on that income, reducing the lost interest to £182.(yes I know about ISAs)

3.

50% of the average consumption of 3300 kW which would be say 1850 x 12 p = £222.00

You use 3,500kWh as the assumed generation 50% would be 1,750kWh. However you change it to 3,300kWh, but then use 1,850kWh(which is 50% of 3,700)

Thus I think a saving of £220 a year is wildly optimistic. Even if you have a Hot water tank, and a device to divert surplus generation(e.g. Immersun), you cannot use 12p/kWh in your calculations. You are saving at the cost of the fuel you would use normally to heat water(gas/oil/E7)

So I would think Martyn's £100 might be a good average savings figure.

The capital cost of the Immersun needs to be factored into the equation.

Lastly the cost of possible repairs also needs to be factored into the equation. Not just the cost of a replacement inverter(or insurance) but someone to diagnose any possible fault.

John_Pierpoint

Don't forget that the efficiency of a gas boiler heating a hot water tank, when it feels like it in. the summer is not running at anything remotely like 90%.
Use of hot water in the summer should be "free" vut very much depends on your consumption.

Regulations in the UK mean you are not legally allowed to "repair" your own inverter, but that said a good inverter displays all sorts of information about its healthy performance, including warnings, if it is starting to feel peeky.

Battery storage, to get over the evening hump in demand and possibly for running a low voltage circuit for your lighting and electronic stuff is also another possibility - running LEDs and trying to toast then with 240V makes no sense at all.
The big prize, not yet realistically available, is recharging your electric car.

Cardew wrote: »

The capital cost of the Immersun needs to be factored into the equation.

......and you might well need to monkey about with your plumbing to stop the hot water tank with it thermostat at the top of the tank, cutting out because the 1/3rd of a tankful has stratified.

jimmyboy420

What's wrong with running 240 volt LEDs?

Robwiz

The difference between using solar PV and a gas boiler is not as simple as comparing the rates per kWh between the two fuels.

I have a non-condensing boiler rated at 28 kW. It takes around 30 minutes for the circulating water in the pipes to come up to temperature and to heat 162 litres of water in the cylinder, I need to run the gas CH for one hour in the morning and another hour in the evening. If the flow temperature is set on its lowest, the boiler uses 14 kWh per hour but the flow temperature is not sufficient to raise the DHW to 60º. If I set the flow temperature on maximum, the boiler uses 32 kWh per hour until the DHW thermostat temperature is reached.

Obviously the pipe run between the boiler and the cylinder coil in the airing cupboard is losing heat - which in our case is wasted as the pipes run through the loft. Furthermore, we have two bathrooms with towel rails that are plumbed in before the three way valve and are alway heated when the boiler is running. I can't close them off as they were a design requirement to protect the boiler from overheating/short cycling.

From daily meter readings with the heating off, my typical gas usage was 44 kWh per day for hot water and towels. The cost of gas is £1.54 (daligas 3.5p/kWh) plus 60W x 24 hours for the electricity powering my boiler and controller on (1.5 kWh of electricity at 11p/kWH, say 16p) which takes my daily cost to £1.70. I have ignored the cost of running the circulating pump.

I have a 1kW element in my immersion heater. It is timed to be on for 3 hours before we get up in the morning and 3 hours at lunch time (when our panels should be producing at least 1kW surplus between March and October). The gas boiler is switched off. Therefore, my hot water costs me a maximum of 33p per day in summer – a saving of £1.37/day and at worst 66p/day in winter on days when the panels don't generate 1kW at midday. It could be that in mid-summer our panels will generate 1 kW at 7 am – I don't know yet.

The conclusion I draw from my monitoring is that generalisations like 'it's cheaper to heat water with gas than electricity' may not always be true – so much depends on the boiler efficiency, the design of the house and how your central heating has been installed. I suggest people experiment with their own system to find out how it performs and then look at your own cost comparisons.