Solar PVs - worth the investment?

purple_hamster

As the interest rates are so rubbish now (and I do appreciate they might not always be this bad), we are considering investing in solar PVs. I know the tariffs have dropped significantly, so is it still worth the investment?

I'm particularly concerned about what would happen if they had a fault, or say, something hit them and broke them? Would we have to pay for repairs?

Other than cleaning, is there any maintenance needed? Or other costs?

I'm completely sold on them in terms of green energy, but it's still a lot of money!

And how do I find a good company (other than a google search)? I don't know anyone locally who's had any installed, short of walking round the neighbourhood and knocking on doors!

Martyn1981

purple_hamster wrote: »

As the interest rates are so rubbish now (and I do appreciate they might not always be this bad), we are considering investing in solar PVs. I know the tariffs have dropped significantly, so is it still worth the investment?

I'm particularly concerned about what would happen if they had a fault, or say, something hit them and broke them? Would we have to pay for repairs?

Other than cleaning, is there any maintenance needed? Or other costs?

I'm completely sold on them in terms of green energy, but it's still a lot of money!

And how do I find a good company (other than a google search)? I don't know anyone locally who's had any installed, short of walking round the neighbourhood and knocking on doors!

Hiya PH, PV is a tough call these days economically, however, add in the green side, and you will hopefully be ok.

For the numbers, you will need a low price, nothing else works these days, so slick salesmen explaining high future leccy prices are no use to you - you simply have to invite lots of offers and explain the price has to be very good.

First of, have a read of sections 1 & 2 of the FAQs.

These were compiled by PV'ers, with no links to the solar industry.

Try to work out how much PV you can install. That will be roughly your roof space, leaving 300mm (or possibly 200mm) spare on all four sides. Then try to see the best way to fit as may panels of 1.6m by 1m as possible. The bigger you go, the cheaper the price will be proportionately.

Then have a play with PVGIS, see section 5, and get a good guesstimate of generation.

From there you'll be able to work out your income (FiT + Export + leccy savings). Divide that by the cost, and see what sort of gross return you will get. 8% or so might be the lowest figure to aim for.

Maintenance - there really isn't any. Rain will clean the panels. Obviously something could go wrong, fail, break etc, but with PV that's very unlikely. So your only additional expense will be a replacement inverter as and when it wears out. With fitting that might be £800(?) Hopefully it'll last for 10 (even 20yrs), but you can extend warranties if you're unsure. They tend to start at 5 or 10 yrs, with extensions upto 20yrs.

There's loads more to ponder and chat about, but it's hard without knowing what you can fit, where, what income, budget etc. So have a read and a play and a think, then chat away.

Mart.

purple_hamster

Thanks Mart. Very useful info. I can't get into my loft to measure the space (we don't have a loft ladder and I'm a wimp!) So I'll have to get my protractor out and do some sums! I've had a look at PVGIS and it says 3800 per year, but that's with the standard roof pitch as I don't know it. I worked that out to being £250 tariff per year, but not sure how much we'd save in terms of power used.

Martyn1981

purple_hamster wrote: »

Thanks Mart. Very useful info. I can't get into my loft to measure the space (we don't have a loft ladder and I'm a wimp!) So I'll have to get my protractor out and do some sums! I've had a look at PVGIS and it says 3800 per year, but that's with the standard roof pitch as I don't know it. I worked that out to being £250 tariff per year, but not sure how much we'd save in terms of power used.

No probs.

If you can work out pitch, that'll help you be more precise, but if you play with the angle on PVGIS, you'll see it doesn't make much of a difference for a south facing roof. But it gets more important as you get further from south.

Hopefully you can get a pretty good guess of the roof, from the ground, measuring the width, measuring the floor, by halfing the house measurement, then guesstimate the roof using the MKI eyeball, (probably 2m to 3m high) to give you the hypotenuse.

Leccy savings, oh boy! Always a tricky one. The salesmen will suggest 50% of generation, but that's hard to achieve. 50% of import might be doable if the house is used during the day.

How many of you are there, anyone home daytime, what is your current import as high users will normally save more (use more of the generation).

If you are comfortable doing so, post your approx location (nearest city?) and someone may have an installer recommendation, assuming they are still in business.

BTW 3,800kWh makes me think it's a 4kWp south facing system. Remember, there's no tariff break at 4kWp anymore, so if there's room, perhaps fit a bit more.

Mart.

purple_hamster

THanks again!

We are four - two adults, two primary school age children. I'm at home most of the time. We face roughly SE. In London/Essex. In the year to Sept 2015 we used 2750 KW. Obviously I don't know how much was used during daylight hours! I tend to run the washing machine etc during the day.

Two more questions that occurred to me:

1. what happens about the guarantee if the company goes out of business?

2. Does the inverter need to be near the fuse box/elec meter? and how big is it roughly (physically!)?

ASavvyBuyer

purple_hamster wrote: »

THanks again!


Two more questions that occurred to me:

1. what happens about the guarantee if the company goes out of business?

Make sure that the guarantee/warranty is insurance backed, so you can claim from the insurance company.

2. Does the inverter need to be near the fuse box/elec meter? and how big is it roughly (physically!)?

No, it can be anywhere, but most companies prefer to put it in the loft. However, as it contains electronics it is better to put it in a cooler environment. We had ours installed in the garage under the house; which helps to keep it cooler (so it should last longer). The size varies, but ours is about 250mm by 500mm, but mounted in the middle of a backing board about 1 metre square.

Martyn1981

purple_hamster wrote: »

THanks again!

We are four - two adults, two primary school age children. I'm at home most of the time. We face roughly SE. In London/Essex. In the year to Sept 2015 we used 2750 KW. Obviously I don't know how much was used during daylight hours! I tend to run the washing machine etc during the day.

Two more questions that occurred to me:

1. what happens about the guarantee if the company goes out of business?

2. Does the inverter need to be near the fuse box/elec meter? and how big is it roughly (physically!)?

Hiya. 4 of you will help, but to be fair, your consumption of 2,750kWh is very good (for 4). To be fair, you probably beat the two of us (here) as import was 2,700kWh just before PV, but we also switched to an induction hob, so I don't know what our consumption now is. But import is now below 1,600kWh.

Our leccy savings are about £170pa, but we have a large system with an E/W spread, so good generation from early to late - but pretty poor in the winter, being off-south.

Regarding your guarantee, make sure it's insurance backed, in case the company folds.

The inverter can go pretty much anywhere you have room, even outside if it's an external model. There are arguments concerning losses between the inverter and consumer unit, but these are very small.

Inverter dimensions will vary, but for something in the 3 to 4kW range, perhaps (in old money) 2ft tall, 1.5ft wide, 0.5 to 1ft deep. Plus you want space around for cooling and air movement.

Here's a spec sheet for a popular model.

Mart.

purple_hamster

We are about to switch to an induction hob (from gas) and also gas to elec oven. It's good to hear our useage is low!

It's good the inverter doesn't need to go in the fuse/meter cupboard then as there's not a lot of room in then. Therefore dimensions don't matter!

purple_hamster

Dimensions are:

width of house (ext) 6m15
half of back to front (ext) 3m95
roof height (guess) 3m (I know it's more than 2m anyway!)
google calculator says the hypotonuse is 4m96

We have a chimeny in the middle of the roof at the heighest point.

I've been calling round companies this morning, but most of them either aren't answering or don't do PVs anymore. I've only got two leads so far!

Martyn1981

purple_hamster wrote: »

Dimensions are:

width of house (ext) 6m15
half of back to front (ext) 3m95
roof height (guess) 3m (I know it's more than 2m anyway!)
google calculator says the hypotonuse is 4m96

We have a chimeny in the middle of the roof at the heighest point.

I've been calling round companies this morning, but most of them either aren't answering or don't do PVs anymore. I've only got two leads so far!

Same as us then on the main roof (6m by 5m). We had 1.3m by 1m panels fitted in a 5 by 3 portrait pattern (but only 13 panels due to a Velux).

You'd probably go for something like 3 by 4 panels landscape, so 4.8m wide (3 x 1.6m) and 4m high (4 x 1m).

12 panels isn't a lot, but 285Wp panels would give you 3.4kWp, which is nice. There are more powerful panels (high efficiency panels) but they cost quite a bit more, but worth pricing up.

Your useage seems very good. The average varies, everytime I look it up as suppliers, OFGEM, DECC vary a bit, but a medium house is somewhere in the 3,300 to 3,800 range, so for 4, you are doing great.

Mart.

purple_hamster

Now I've booked two companies in to visit next week. They are "assessors". Is that the same as surveyors?

Is it worth having an invertor that can have batteries added in the future (when prices come down)?

I'm trying to think what else I need to ask them!