[slippyr4]

I've had panels since 2012 and this year is the first year I've had pigeons trying to nest under them.

In terms of leaks - panels are mounted on rails which are screwed to brackets which go up behind the tiles; tiles don't get holes drilled in to them or anything. So long as your roof is sound and your panels are installed properly, it won't leak.

 

[Jim R]

Fantastic replies from everyone. Really appreciate all the information and so much to think about. Thank you very much!

At present we would be looking at 8 panels (8 x 390 = 3,120 system?). I am thinking even with a battery, would it be worth it for the cars? Thinking maybe a fewer panels that could feed the 'background' electric usage in the house.

Definitely would get the netting following my reading here!

 

[cah197]

At present we would be looking at 8 panels (8 x 390 = 3,120 system?). I am thinking even with a battery, would it be worth it for the cars? Thinking maybe a fewer panels that could feed the 'background' electric usage in the house.

Probably not worth it for that size of panel. If you can use some of the energy to heat hot water, then that's a good way of using the energy.

What rate can you sell to the grid vs the cheapest night time rate?

 

[Jim R]

Probably not worth it for that size of panel. If you can use some of the energy to heat hot water, then that's a good way of using the energy.

Apart from the EV's, we heat the house and water via a gas boiler (There is an immersion). We cook with electric (Induction hob, twin fan ovens).

My thinking is maybe an smaller array (1560) (Presently planning 3120) that would feed a smaller battery (less than 6.4kW). This may be sufficient to run the house in the evening. Charging of the EV's would be via Octopus in the early hours. Reasonable approach or a long way out?

What rate can you sell to the grid vs the cheapest night time rate?

How do I find that information?

 

[Naturetech]

Solar panels are cost-effective provided you can use the power you generate, by having a solar diverter for an immersion heater etc. If you can't, don't bother. Adding a battery will only dig you a deeper hole financially. Their cost means they're not financially viable right now.
With regard to your proposed solar array, are you aware that with a South-facing system you're only going to see full capacity generated between about 11:00 & 13:00 from May to August? Most of the time you'll be generating a few hundred watts.
My above comments are based on experience. I don't know about Octopus tariffs though, but they may sway you towards a battery system to save the solar-generated power. The only thing is, you'd be paying to keep it ticking over for 6 months of the year when there's not much solar generation.

 

[Jeremy Harris]

This thread has some good advice. We have 25 solar panels built in to our roof (they are the roof covering on one side - no slates underneath) and these can generate around 6 kW or so under the right conditions. We manage to use about half of the electricity they produce, for heating hot water, cooling the house during the summer and a small amount for charging the cars (it is far from easy to use much solar generation for car charging). We end up exporting around 3 MWh a year to the grid, because we cannot easily use it, mainly because most of the generation is at times when we just don't need any power.

Winter generation is generally rubbish, and doesn't do much at all. For around 4 months we get virtually no usable power from the system, and what we do get barely offsets the 200W to 400W house baseload, and does nothing else that's of much use.

Batteries just don't make economic sense at all, even as a DIY job at the very lowest price I can find. I'd love to install them, and have already put the cabling in and built a shed to house them, but I know that they will die of old age before they have saved their purchase price. I still may do it, though, as not everything we do needs to be because we can save money, there are other good reasons, not least of which is the fun aspect of having a new project.

 

[cah197]

Adding a battery will only dig you a deeper hole financially. Their cost means they're not financially viable right now.

This, unfortunately is quite true.

I'm currently using about 75% solar energy, with the rest drawn from the grid. When my battery system gets up and running that should allow me to get damn close to 100% self powered.

However the logical approach to charging EVs is to get a cheap overnight rate and charge then, and feed excess solar back into the grid.

The marginal rate for me if I did this works out at less than 2p per kWh. So much cheaper than trying to use a battery to do it will all the limitations that come with that.

Although as a general rule I'd try and get as many panels as possible on your roof. The big problem in the UK is cloud cover - nothing wrong with the actual sun.

 

[Trevor Larkum]

Calling @Trevor Larkum !!!

Thanks for the heads-up! Unfortunately I'm so busy quoting for solar installs that I can't spend much time on the forum. Things are going mad, with a lot of kit now out of stock until the end of July, and getting worse.

My suggestion is that if you get panels, get the installer to put bird prevention measures in place at the same time. Its a lot cheaper when the scaffolding is already up there

This. An increasing proportion of our customers are having this added. Although it will cost from about £500 on the day, if you have to add it later you will also have to pay £700+ for scaffolding on top.
I've blogged about the different options here: Solar Panel Bird Control Systems

As a general point I am more upbeat about batteries than a lot of people on this forum. Pound for pound they don't payback as fast as a solar install for people who are at home all day, but:

if you are not going to be home then you will need a battery to have any benefit of the solar panels.

Exactly. You can also reduce your payback by charging them overnight on cheap electricity, particularly in the winter when the solar generation dips. I also like the fact that my house keeps going in a power cut (with additional hardware) and am happy to pay a premium for that capability.

The most important advice is to maximise the panels in an install because there are big fixed costs (particularly scaffolding and an electrician - typically paid for the day). Roughly speaking we can install a 4kW system for about £5k, but an 8kW system would only be about £8k.

 

[Jeremy Harris]

I also like the fact that my house keeps going in a power cut (with additional hardware) and am happy to pay a premium for that capability.

This is the main reason I'm trying to convince myself to install a battery system.

The saving in electricity cost, even for our all-electric house, will take a bit over 13 years to cover the cost of the cheapest battery system I can find, with me doing all the installation work to reduce the cost further. That's taking in to account winter load shifting from peak to off-peak rates as well, so shifting our present 56% off-peak, 44% peak usage to close to 100% off-peak, as well as reducing the overall total from being able to utilise stored energy from our 6.25 kWp PV system.

Part of our problem is just that we don't use much electricity, despite the house being all-electric. With the bill being around £50 a month there isn't a lot of money to be saved overall.

 

[Sean Nugent]

How often do you get a power cut. Its a very expensive once a year feature.
Now if you were getting cuts every day - that's a whole different ballgame

 

[garycat]

I've just had solar panels fitted. 12 x Longi 360w (4.3kW) and a GivEnergy 3.6kW hybrid inverter with 8.2kWh battery.

Cost was just under £8K but they added a Zappi for another £880. We are in a bungalow so scaffolding may be more for a house.

Really pleased with the system so far, the amount of power we pull from the grid is negligible. FiTs are no good these days, so it will help charge the car and hot water (when I get an Eddi)

If you're in the south west, I can recommend Solar PV | Ecobubl Ltd | Warminster They were £1.5K cheaper than another quote I got.

This was a sunny day last week. Blue is 25kW generated, red is from the grid.

 

[MudflatsRichard]

Seems you got a good deal, Garycat. I know prices are continuing to fall, but I paid a lot more than that nine months ago for my similar system. And yes, I'm in the South West, didn't know about Ecobubl. Will keep them in mind for when I install my heat pump...

 

[Trevor Larkum]

This is the main reason I'm trying to convince myself to install a battery system.

I've blogged about the options here if you're interested - I have a Level 5 system: Power Cut Backup Options with Battery Storage

 

[HandyAndy]

Had my panels since 2015 now. They started as a 4kW nominal system, 16x250W panels, facing due East at shallow 70's roof angle. Thx to the direction they maxed out at 3kW, so I've added 3 more larger & South-facing panels on garden shed to make it up to 4kW max. These extras don't get the FIT though.

Being East facing is actually rather useful, as the moment the sun's up I get about 2kW before I know it (at 7:15 this morning), and that's heating the immersion tank via Solic 2000 diverter from the word go. As noted above, South facing gives you max kWh out, but in a rather hard-to-manage burst around mid-day. Splitting the panels for an East-West setup would be ideal for me, and would supply a far more usable steady output for longer than pure South-facing, but wife won't dream of that as the West 1/2 of roof is visible from the road!

Being retired I can trickle charge a lot, so that's super valuable to me.
Over a year I generate 4000 kWh from the panels, house import from the grid has dropped from previous 4000/year to 3000/year, and once I'm back to doing 12k miles p.a. I'm expecting that to use the remaining 3000 units, so in effect I'm getting 100% green EVing, by using the Grid as my long-term battery. I just have to pay the regular price for reimporting it back when needed in winter.

 

[KenB]

Over a year I generate 4000 kWh from the panels, house import from the grid has dropped from previous 4000/year to 3000/year, and once I'm back to doing 12k miles p.a. I'm expecting that to use the remaining 3000 units, so in effect I'm getting 100% green EVing, by using the Grid as my long-term battery. I just have to pay the regular price for reimporting it back when needed in winter.

Only if you have a backwards running capable meter i would suggest. How often will the car be able to be charged when there is also the PV available. Of course if you have 2 EVs or an ICE then it becomes more possible.

If one has 2 EVs that can use the PV and TOU tariff like Octopus GO for winter car charging then that reduces the financial case for batts i believe.

 

[Tigga]

You may want to research solaredge optimisers, which is like an individual inverter per panel.
Solaredge also offer an inverter with built in ev charger in one unit.

they are called micro inverters... basically there are different ways to wire multiple solar panels (in parallel or series)... they have pros and cons to the methods, but they are then limitted by the lowest output panel in the string. This means you could have one panel shaded and that so all the panels suffer and they can only generate as much as the smallest one!

Using micro inverters, each panel is independant, so shading on one panel doesnt bring the string down.
10 years ago this was an expensive method and people couldnt afford it, but like everything, the costs have come down and now it is really the best way to install panels for 90% of people. Way more efficient and much less energy loss. (solar tiles work this way... lots of roof tiles with microinverters!)

Are panels worth the expense?... I've had mine 6 years.
Im on a feed in tarif which is ok, but not as good as friends who installed before me. So I've just about paid them off now but only because I give nothing back to the grid. (smart meter shows the export to be sub 50kW over last 12 months.) I use everything!!!

When we can do car to grid, this will be really good for me to offset the daytime stored power and the nighttime cheap rate... then I would have more hours of zero peak time grid with solar, offset with increased use of cheap rate grid. (using octpus go!)

If I was designing the setup again, I would put on more panels, use micro inverters and add a battery so I can offset the useage.

 

[Tigga]

Ideally your house sits south facing to maximise sunlight. Now for us, it wasn't about how much electricity we'd make or dreams of 'going off-grid'. Invest in battery storage. We fitted a 4 kW system (16 panels) and 5kWh battery bank. My wife comes home after work and plugs in her i3 decimating the energy it accumulated and stored, but hey that's life!

Don't get hung up on figures and end up like a parody of the Good Life. What is the bank or building society giving you for your hard earned cash, nowt! It is interesting as we get into summer to see the batteries full and everything else electrically powered is for free!

swap to a zappi (I know easier said than done) and then prioritise the car to charge at night during cheap rate and also have the batteries charge off the grid at night too, if you change to octopus go that will mean 4 hours of 5p per unit at night, as opposed to 15p per unit daytime.

Put the dishwasher and washing machine on a night too, and then you will be puting most of your usage in cheap rate period and daytime running off the solar and battery during the day.

I think you could find you save a small fortune over a year, especially if you can be off grid in the daytime.

 

[Tigga]

Solar panels are cost-effective provided you can use the power you generate, by having a solar diverter for an immersion heater etc. If you can't, don't bother. Adding a battery will only dig you a deeper hole financially. Their cost means they're not financially viable right now.
With regard to your proposed solar array, are you aware that with a South-facing system you're only going to see full capacity generated between about 11:00 & 13:00 from May to August? Most of the time you'll be generating a few hundred watts.
My above comments are based on experience. I don't know about Octopus tariffs though, but they may sway you towards a battery system to save the solar-generated power. The only thing is, you'd be paying to keep it ticking over for 6 months of the year when there's not much solar generation.

not sure I understand your argument here! not true most of the time you generate a few hunderd watts.
And having a solar diverter will reduce your bill for heating water (so either gas or oil depending on where you are)... this avoids putting anything back to the grid. You want to use everything, so putting the peak generation anywhere other than the grid is worth while.

If you can generate 2500-3000kWh per year... use 95% of this... even if putting into heating water, you are saving around 400-500 pa. in the fuel bills. diverting some costs from the gas/oil.

If you add a battery and then use octopus go... charge the battery at night and use in the day, this puts you closer to zero grid during day time... and you pay about 1/3 the price for electric at night.
This quickly adds up to a few hundred more saving per year when using smart management of the appliances and car charging.
In the summer you will be pretty much off the battery for most of the time. (8kW + what you harvest from excess, so that should last most of the day); so could be as high as 16kW per summer day. Winter you will be saving 8kW in peak time, so at least £1 per day saving... even over 6 months, that still £180 each winter. easily £500+ saving.

Its not inconceivable to be saving close to £1000 per year with smart setup. YES the capital outlay is high, but 6-8 years payback, the feeling good about being green, the increased value to the property all add up to make the investment worth considering rather than dismissing.

 

[Peter Cittern]

I've got 3.8kW of solar and a house battery. I've shifted most of my usage to E7, I've reduced my daytime grid usage by 90 percent so I now only use about 200 units a year of daytime. Works well, but it is a bit of a hobby!

 

[Tigga]

I've got 3.8kW of solar and a house battery. I've shifted most of my usage to E7, I've reduced my daytime grid usage by 90 percent so I now only use about 200 units a year of daytime. Works well, but it is a bit of a hobby!

I can beleive that! You will need to monitor and tweak things to optimise the setup.
Its a feedback loop to get the best out of the system!