20 panel commercial use payback

[Paul2129]

I've just had a quote for a 20 panel install, this is for a commercial building where our electriciaty cost is approximately £4000 a year, predominately lighting (where we're using mostly Fluoro warm whites due to us selling carpet.... we're kind of used to the colour cast and aren't keen on LED replacements) we use some fan heating during the day, and have (only 4) storage heaters during the winter. I 'think' we used 30,300Kwh last year.

     Half the panels are on an east facing roof, and the other half on a flat roof at the back of the building, this flat roof is in a slight shade, quoted at 25%. I'm told that the system is 5.4kwp / 3760Kwh,  that the FIT scheme would pay £149, exporting energy gets me maybe £90, and based on 30% self-usage, we'll generate £158 in electricity savings. So we're talking £400 per year, meaning I'll be something like 17.5 years before I see a break-even point. This from an install with a cost of around £7000 +vat

     I quizzed the gentleman who quoted me, about the 30% usage of what we generate, bearing in mind that we are open 6 days 09:00-17:00. We have no battery storage, but we're shut during those evening hours anyway. He revised his estimate and said maybe we'll use upwards of 75% of what we generate, and this brought the break-even point to about 8.5 years..... now I'm not sure what to believe

firstly, I can't believe how little electricity that 20 panels create, 3500KW is about a tenth of our consumption 

perhaps this lack-lustre performance is due to our orientation to the sun, we ain't perfect in that respect ?

a sub 10 year break even was my hope, at 17 years..... I've lost interest

I really wanted this solar idea to work out for me, but if the sum total generation for what I'm calling 'two roofs worth' of solar panels is £158..... I wonder if it's all worth it

getting used to the colour of those LED's might have to happen !

any comments on my ramblings would be appreciated

paul 

 

[ProDave]

30,300 KWh per year is 97 KWh per day (assuming you are closed on Sundays and not allowing for bank holidays)

Over the working day, say 9 hours? you are averaging a load of 10KW.

I know that's a gross over simplification and not taking into account the storage heaters etc, but what the hell are you using to be running at 10Kw most of the time you are open?

A 5ft flourescent is 58W Do you really have 172 of them?

I'm just staggered by the usage.

Perhaps, rather than solar PV, you need a whole lot of skylights on the roof to let some daylight in so you can turn a lot of the lights off?

 

[Lurch]

our electriciaty cost is approximately £4000 a year,    [...]    I 'think' we used 30,300Kwh last year.

You would be better off switching suppliers. I pay about 10p (or 10.something anyway) per kWh for a commercial unit, and I use a hell of a lot less than you do. Doing that would save you 1k per year without even laying anything out.

 

[binky]

biggest pile of diatribe I've seen for years.

1/ 20 panels at 250w is at least 5kWp system and most panels start at 265w these days

2/ commecrail premises we normally work at about 75/80% self use, your open during daylight hours when the panels generate max and given your energy use I doubt much will go back to the grid

3/ a domestic 4kW system is probably worth more a year than those figures where self use is more like 30%

Unfortunately the decimation of  the FiT means figures are much reduced, but the main focus should be putting a hole in your leccy bill, which at roughly 15p per kWh should be around £750ish

try another company, like a small local outift and get some decent advice. This gut clearly hasn't got a clue.

With regards to LED lighting I would opt for 'natural daylight' - it gives full colour spectrum, so should show your carpets off better.

 

[Paul2129]

Re the unrealistic or high usage figures, I'd have to have a count up of lights during the day. It does seem a lot I know.

     Also, weirdly, I've been getting phone calls from India, some people are claiming that the national grid have made some mistakes on the quantity of units used (not aware that the national grid had anything to do with calculating my units ? The energy provider quotes start/end figures for the period ? But anyway, these Indian guys reckon it's effecting my bill by 40%, would be nice if they're right, somehow I'm doubting it !

p.s, for quantity of lighting, we have 'maybe' 45x 6'-0"ish Fluoro' as well as various display lighting. All the front fluros are on 365 days /24hrs...... and all the lighting we sell, maybe 30 or so, are mostly LED's. Upstairs we have another 40 fluros but the lot are on a timer, we hit the button when customers go upstairs and they turn off after 30 minutes

 

[Barx]

biggest pile of diatribe I've seen for years.

1/ 20 panels at 250w is at least 5kWp system and most panels start at 265w these days OP states 5.4kWp (270w modules )

2/ commecrail premises we normally work at about 75/80% self use, your open during daylight hours when the panels generate max and given your energy use I doubt much will go back to the grid

3/ a domestic 4kW system is probably worth more a year than those figures where self use is more like 30%

Unfortunately the decimation of  the FiT means figures are much reduced, but the main focus should be putting a hole in your leccy bill, which at roughly 15p per kWh should be around £750ish

try another company, like a small local outift and get some decent advice. This gut clearly hasn't got a clue.

With regards to LED lighting I would opt for 'natural daylight' - it gives full colour spectrum, so should show your carpets off better.

 

[Barx]

What portion of the system will be on the flat roof and what do you call a 'slight shade'?

In my opinion a flat roof is not worth bothering with unless it is perfect due to the additional price for the mounting gear to get the panels at a working angle.

To get the best out of a system where shading is unavoidable, you need to be looking at optimisers, but again this is extra cost.

 

[Paul2129]

Well, we have a lot of roof space, half of the panels are on the East facing pitched roof, and roughly half are on the flat roof. I think (I do have the report somewhere) that the shade was quoted or calculated at 25% for the flat roof or perhaps the panels quoted at 80% of their potential ?. I have the report but it's a little complicated. This flat roof is pretty huge, but surrounded on east, west, and worstly south sides with pitched roofs from the sun. At 09:30 on the day of the quote, the entire roof was sat in the shade... the electrician (who would appear honest) said that it would be receiving a more direct sum for the majority of the rest of the day, after the sun moves away from the east facing panels. Saying that this spreads the panels out for usage across all hours of the day..... there are t many more options here

im wondering if 'just' the east facing panels would be much cheaper / worth it / big enough to bother with ?

there were options to have two more panels on each of the flat and pitched roofs, so if I were to not bother with the flat roof, I could at least at two extra panels to the side ?

edit : just checked, this original quote has 12 panels on the East facing pitched roof, and 8 panels on the flat roof

.edit : quote says PV modules are 270w

 

[binky]

that's quite a heavy shading factor. Could you post a google earth view of the roof so we can get a better idea of what you are talking about.

There's a few other factors to consider.

1/ what your connection to the grid is, ie single phase, 3 phase or something else. Rule of thumb is that we are allowed 4kW per phase. Bigger connections are allowed by approval from the grid operator (DNO) sometimes - needs to be applied for before commencing works.

2/ East / west arrays offer better power spread, but for your opening hours something more south facing might be better, unless you have electrical items running all day and night like web-servers, window display lights etc etc.

3/ it sounds like it is really worth considering energy saving measures like LED lighting over installing panels

4/ albeit the figures aren't great, you have to consider the energy savings over 20 years (and beyond, the panels don't stop working when the FiT payments stop). Add energy inflation at 5-6% a year and it all looks far more interesting

5/ I'm not  a fan of flat roof arrays either, they can be a bit complicated at times, but if you can get some due south panels as a result, then it can work for you?

as a sales point, 'going green' can be useful for promoting your business

 

[Barx]

any chance of you posting a link to your place on google maps, so we can see what you have available?

Bah, Binky beat me to it lol.

 

[ProDave]

Well the VERY first thing I would do is turn those 45 6 foot florry's OFF when the shop is closed. That is absolute madness to leave them on 24/7.  At the flick of a switch (or timer if you can't trust staff to flick the switch) you will more than halve your electricity bill at no or minimal cost.

Then solar PV makes a lot more sense as Binky has pointed out if most of your usage is in the daytime.

Given that the FIT is so low, it appears the self use saving exceeds the FIT payment.  I have o question is it actually worth claiming the FIT?  In order to claim the FIT you have to use an MCS registered installer many of whom seem to charge a premium because they know they are the only ones that can do it.  forget about the FIT and any electrician can fit them probably a good deal cheaper than an MCS company?  That is certainly how I am looking at it for when I install PV on my new build.

 

[Paul2129]

Interesting points, thank you for your replies. Fluro's are only on in the windows overnight, the rest are off after 17:00

i tried a link to google : Dropped pin
near 139-145 Victoria Rd W, Thornton-Cleveleys FY5 3LA
https://goo.gl/maps/kkErdi52g7Q2

we're three out of the four shops, looking at the left side of the block, draw a line through from the back on the car parked on the pavement, through the red bins in the back yard, everything to the left of that line, one single shop is not ours, the rest is, 

The white van is nosing in towards the intended pitched east roof, then the flat roof should be obvious

 

[Barx]

Assuming it's the pitch to the left of flat and that you don't own the larger pitch to the right?

That flat roof is a tough call.............

Along the top of the dormas at front looks another possibility, but again not sure if it will be worth the cost of getting up there.

 

[Paul2129]

The very right side pitch of that building is ours, the white van points toward it in the photo. It fits 14 panels apparently.

     The electrician said no, right away, to the front where the dormas are

 

[binky]

Hmm, think i would opt for a system on the front, using high wattage 330w panels and possibly right hand side down the lane adjoining shop - if you can get scaffold up without blocking access. beyond that the flat roof has too much shading except at far rear where tree will drop leaves and detritus all over the panels.

I would work on cost effective hole in the bill by keeping PV scheme simple, and put money saved to replacing lighting with LED

 

[binky]

Given that the FIT is so low, it appears the self use saving exceeds the FIT payment.  I have o question is it actually worth claiming the FIT?  In order to claim the FIT you have to use an MCS registered installer many of whom seem to charge a premium because they know they are the only ones that can do it.  forget about the FIT and any electrician can fit them probably a good deal cheaper than an MCS company?  That is certainly how I am looking at it for when I install PV on my new build.

I will be de-listing MCS this year. and focusing on repair work. We do charge a premium, but then we have big risks, large paperwork system to run, and additional costs like warranties on systems fitted. However, that doesn't mean a free-for all to stick panels up, you still need training to cover insurance. If your system caught fire, insurance company will be asking if you are competent to fit PV and I would suspect would refuse to pay-out on a claim unless you can demonstrate competence by holding a training cert or two! Like most things it isn't quite as easy as it looks anyway, though most of the difficulty is in speccing the system and old roof coverings.

 

[Paul2129]

I'm going to start working through with LED tubes, one of the side shops first, and see how it looks. Maybe we'll max out the number of panels on the east facing side and leave the flat roof..... I wonder then if we'll ever generate enough to make it feel having been worth it ?

 

[Barx]

I'm going to start working through with LED tubes, one of the side shops first, and see how it looks. Maybe we'll max out the number of panels on the east facing side and leave the flat roof..... I wonder then if we'll ever generate enough to make it feel having been worth it ?

Without personally seeing the property, It sounds like that would be the way to go.

 

[Lurch]

I'm going to start working through with LED tubes, one of the side shops first, and see how it looks. Maybe we'll max out the number of panels on the east facing side and leave the flat roof..... I wonder then if we'll ever generate enough to make it feel having been worth it ?

First thing would be switch energy suppliers. No outlay and instant savings.

 

[binky]

I'm going to start working through with LED tubes, one of the side shops first, and see how it looks. Maybe we'll max out the number of panels on the east facing side and leave the flat roof..... I wonder then if we'll ever generate enough to make it feel having been worth it ?

you have to take a long term view, HInckley point has to be paid for, the worlds' population continues to expand ergo fossil fuel energy will be become scarcer and more expensive. Whatever hole you put in the leccy bill insulates you against future price hikes and inflation.

It's also why I'm suggesting you keep the system simple, lower initial outlay will give a better Return on Investment. Try natural daylight LED tubes, they give full colour rendition, helps display the carpet colours better, feels better for your staff, and are good for the visually impaired (ie old folk). They take a bit of getting used to as they don't feel like the lights are on.