Solar PV – Frequently Asked Questions and Answers

sly_dog_jonah

Martyn1981 wrote: »

The following site can be used to compare your output with the expected output for the actual weather conditions recorded at your location (you will need to register first):

http://solargis.info/pvspot/index.htm

Unfortunately this site now says the following when logged in to view my system:

This PV system is in demo mode, only sample of data is available for preview. Please contact us for ordering license to continue with data delivery.

So the data is no longer available for free. You don't even get a short trial period of live data after initial registration of a system. Apparently the license cost is 120EUR+VAT/year.

Martyn1981

Hiya SDJ, I wondered why I was having trouble with the site. I can't see any data since the 17th of July, and for system 2 (where I put in a 'test' system to see how it would have faired) it'll only show June, nothing before or after.

I think it's a great site for checking that your system is working, but after that, it's value is really no more than fun. No way I'd pay 120Euro + Vat. Maybe £10 per year as an indulgence, but even that would be a guilty pleasure, and possibly a nolvelty that would wear thin quickly.

I still think PVGIS climate estimates and a monthly check of the MET Office anomaly maps will confirm system performance. And any new posters can always ask 'the old firm' for comparisons.

I'll chop out that section on PVSpot.

Thanks again.

Mart.

Martyn1981

I've just added a section on extensions, as co-incidentally, the issue has come up a few times recently.

It's a bit quick and sloppy, so comments would be appreciated if it doesn't make sense.

Also, I've just bumped up against the character limit of 25,000 (who knew!), so I had to hack at it a bit. I'll try to do a bit of pruning on the main text, but will be careful not to chop or abbreviate sections 1 & 2 too much. Hopefully the later sections can be trimmed, since by then, most readers will have a reasonable understanding of PV and FITs.

Mart.

Pheiffer

Brilliant, good amount of information there well researched. very helpful.



Pheifferprop

Energetic_2

From an installer point of view a great guide with lots of useful info.

From the same point of view if you're thinking about PV now is a great time, and I would encourage you to hunt out a great deal. I realise I can hardly be considered impartial but I will explain my opinion below. Important points to consider IMHO:

The right installer. This is the MOST important thing. We have installed over 1300 PV panels and have 300,000W of generation capacity to our name and do not have a single unhappy customer. The technology works, it’s proven, and people who've had it installed love it. Problems such as poor workmanship, bad design, poor quality equipment and being ripped off can be eliminated by choosing the right installer. If you do this one thing, you get all the other things right also.

How to do this, again IMHO: Find someone local who has a reputation to preserve locally. A small company has far better control of the quality and is much more likely to offer you help and support after the install than a large one. In the volatile market we are in a prudently run small business is better placed to be around in the future to honour warranty claims etc. than a large company with lots of wage bills to pay, many regional installers are struggling under heavy wage bills.

IMHO its best to find a company who started pre or very early 2011, before the 'gold rush', guys who started then have a good knowledge of the industry and are well placed to explain the merits of different panel manufacturers, the difference between cheap Chinese, better tier 1 Chinese, Korean, European etc... Those who entered later may only be familiar with Chinese.

Choose a company led by engineers or electricians, not salesmen, if the guy who's doing the original survey can't answer basic technical questions kick him out, don't even bother with a quote.

Choose a company who uses PV design software to give you an estimate of yield. PV-Sol and PV-Syst are the best examples. We use PV-Sol and it allows us to build a 3D model of the roof with the correct pitch and orientations, we model in trees, neighbouring properties and anything else that can cause shading. We can select the panels and inverters that we might use to work out the best system for that roof. The software models the impact of the shading in 10min intervals throughout the year and so far our estimates are usually within 5%. This does not and cannot replace the SAP calculation required in EVERY quote by MCS. Depending on where you are in the UK the software can be very different to the SAP calc.

Choose a company that is looking to add value to you system, displays/monitors/power management systems find out if they are included or not.

Panels are important. The Chinese manufacturers are operating at a loss and swimming in debt, expect lots to go bust and lots of mergers and acquisitions, who know where that market will be in 5 years. We advise to choose a company you trust to be around in 10 years to honour warranty claims if anything goes wrong. At the moment we do a lot of Hyundai all black panels, they are well priced, more expensive than many, but good value. A system that looks good can be worth paying a bit more for.

The BEST VALUE is NOT ALWAYS THE CHEAPEST!

There are lots of installers out there keen for work, great deals are available at the moment with superb returns and 6-7 year paybacks. Any claims that an installer makes about 'the best this' or 'the best that' can be verified on the internet. Don't sign anything on the day, don’t go with anyone you have doubts about. This is a big investment, it's important to get it right and to get your head round it all, installers should understand this and should not put you under any pressure to make a decision.

There are lots of great trustworthy local installers who are keen to get the best deal for you, word of mouth is how we survive, and it’s in our interest to make sure you're happy and raving about PV!

Martyn1981

Solar PV Q&A's Index PTII

The following is a list of general topics and questions that regularly get asked on the various MSE solar PV threads. All of the advice comes from enthusiastic PV owners. It should not therefore be considered technically perfect, nor 100% accurate. It should only be considered as shared advice and experiences.
Also please note, there is no such thing as a simple question (nor a simple answer), this post is only meant as a first port-of-call, you will always learn more by chatting on an appropriate thread and gaining additional input and opinions.

Sections 1 to 5 are found here:

Martyn1981 wrote: »

Solar PV Q&A!!!8217;s Index PTI

1. I!!!8217;m only thinking about getting PV !!!8211; What should I consider?

2. I want to get PV installed !!!8211; How do I go about it / What should I do next?!

3. Now I have PV !!!8211; How do I get the most out of it?!

4. My meter is running backwards !!!8211; Do I need to do anything?!
4a Meters reading export as import
4b 3 phase meters
4c Smart meters

5. Estimating generation !!!8211; How do I estimate my monthly/annual generation or check that my system is performing correctly?!

6. Energy monitors !!!8211; How do they work / Should I get one?!

7. I!!!8217;ve had PV installed !!!8211; But what exactly are all the parts called / What do they do?!

8. Getting serious with circuits - some DIY ideas for the less technically challenged.

9. Feed-in-Tariff registration and changing suppliers

10. Adding to an existing PV system, or adding an additional PV system at the same address.

11. Common terms and acronyms used on this site in conjunction with PV and renewables in general.

12. FiT Degressions

13. Basic consumer advice and protection.

14. Inverter shutting down, reporting overvoltage / Grid voltage too high.

(Sections 1 to 5, see link above)


6. Energy monitors !!!8211; How do they work / Do I need one?

Energy monitors can be used to measure/report the amount of PV being generated.

Do you need a monitor !!!8211; They are not essential, but if you!!!8217;d like to know what is being generated at any given time, possibly to help you judge what and when to switch items on (or off), then they can be useful.

There are two main types:

Firstly the more common clamp type. These are relatively cheap, and some energy suppliers will provide them free, or with certain tariff packages. They can also be found for re-sale on popular internet auction sites. It might also be possible to borrow one from your local library, if they offer this service.

These monitors use a !!!8216;clamp!!!8217; that is easily fitted around a suitable electrical cable, and relays information on energy flow to the monitor.

At low levels of consumption or generation (less than 300W) these devices can be very inaccurate, but are reasonably accurate above such levels.

Clamp type meters register the current flowing in a cable - regardless of direction of flow. You cannot therefore be sure whether the indication from such a meter where the clamp has been placed in the usually recommended position of the main feed from meter to consumer unit is showing an export or an import. It can help to show which if you have an easily switchable device (e.g. kettle, toaster etc) alongside the meter. If reading goes up when you turn that device on you are importing; if reading goes down you are exporting. But even that has a problem - e.g. if you were exporting 500watts then switch on a 1000w load you'll then be importing 500w but meter reading would stay the same.

With careful planning, you (or an electrical contractor if your own skills not up to it) should be able to arrange your wiring such that you can fit a clamp around a cable in which you know which way the current is flowing. Fitting two (maybe more) such clamps will allow you to measure consumption and generation separately. Most of the cheaper monitors will only display results from one such clamp at a time so you may need to use several of them and perform some quick mental arithmetic to get an idea of nett usage (or export).

The Wattson meter
http://www.diykyoto.com/uk/

or the OpenEnergyMonitor project
http://openenergymonitor.org/emon)
takes that a stage further by displaying a nett figure for you.

Secondly, systems that monitor the flashes from the LED on the total generation meter (TGM). These devices can only be fitted to suitable meters, but provide an accurate report of energy being generated.


Some recent MSE threads:

Solar Panels and Energy Monitor

Can someone suggest a suitable solar pv monitor

A quick question about Owls


7. I!!!8217;ve had PV installed !!!8211; But what exactly are all the parts called / What do they do?

The solar panels fitted onto the roof, and convert solar energy into electrical energy in the form of direct current (DC).
The DC is carried by cables to the inverter, and will pass through an isolator switch. This safety switch enables the inverter to be disconnected from the DC side (PV panels).
The inverter converts the DC into alternating current (AC) which the electrical items in a domestic property will run on.
The AC is carried by cables to the total generation meter (TGM), and will again pass through an isolator switch. This safety switch enables the inverter to be disconnected from the AC side (National Grid). On some installs, there may be a small consumer unit installed before the TGM.
The TGM records the amount of energy that the system generates in units. Each unit is 1kiloWatt hour (kWh), (this is the same measure used to record imported units that the household buy from their energy provider, which are recorded on the existing import meter.) It is the TGM reading that will need to reported to your FITs provider in order to get your quarterly payment.
Cables then take the AC to the main consumer unit via another AC isolator switch.

NB: Not all installs will have AC isolators on both sides of the TGM. Some may only have one.


8. Getting serious with circuits - some DIY ideas for the less technically challenged.

Some MSE'ers have been playing with their soldering irons to solve some PV related issues. If you're a competent DIY'er and can work with circuit boards, or are just interested in such things, then you may fancy a look at the following links;

Electronics projects for Solar PV

device to use unused soler pv export power to run heater or hot water


9. Feed-in-Tariff registration and changing suppliers

Q. Do I have to register for the FiT with my existing electricity supplier? Or can I pick from any?
A. (short answer) If you're electricity supplier is one of the 'big six' you generally can't register for FiTs with one of the other 'big six'. However if your electricity supplier is one of the smaller (non-'big 6') suppliers, you can choose from any FiT supplier.

Q. Is there any difference between FiT suppliers, for example the amounts I will be paid?
A. Unfortunately yes: there's differences in the following: Service; Registration backlog; speed of payment; method of payment (BACS/Cheque/Credit to bills); 'windows' for submitting quarterly generation readings; methods of submitting readings; some niche providers pay a little extra on top of export tariff.

Q. Once registered for FiTs, can I move electricity supplier without moving FiT provider?
A. Yes, you continue to submit quarterly meter readings to your FiT provider. The Elec/gas switching process should be no different than before.

Q. Once registered for FiTs, can I move to another FiT provider without changing electricity supplier?
A. Yes, subject to the FiT provider allowing applications from non-customers, which may depend on who your current electricity supplier is. There's little incentive to other than to get better service from the FiT provider. The switching process is somewhat of a mystery as few have proceeded with it, probably best to start with the FiT team at the new provider if you want to proceed with this.

Q. What questions should I ask a FiT provider before registering/moving to them?
A. See above question about differences between them, then ask them about those topics. Note many providers are putting systems in place to speed up/automate payments with varying success. There are a number of forums threads specifically discussing problems surrounding FiT payments, but note that past service is not necessarily a reflection of current or future service standards.

Q. What happens if I sell my home?
A. See the following YouGen blogs here and here

Q. My meter goes backwards sometimes when my Solar PV is generating, will this be a problem if I want to move electricity supplier?
A. You should have already notified your FiT supplier and/or electricity supplier that the meter is going backwards. If they haven't actioned that yet, then it may make for some interesting discussions between the 3 parties trying to agree a meter reading at the date of supply transfer.

Q. Will I have problems transferring my FIT?
A. No evidence either way I'm afraid. Perhaps the only known issue you may come across is that most if not all of the 'Big Six' will only accept a FiT application if your Electricity supplier is not one of the 'Big Six' (unless you're intending to move your supply over to them as well).

Q. Can I leave my FIT arrangements with npower and take my "normal" energy from another supplier?
A. Yes. In theory you could use [Company A] as FiT provider, [Company B] as Electricity Supplier and [Company C] as Gas Supplier.


10. Adding to an existing PV system, or adding an additional PV system at the same address.

There is no reason why you can't 'try' to have more PV installed, but there are a few important factors:-

There are two ways to add more PV. Adding additional panels to your existing system, or adding a totally separate system (panels, inverter, and TGM).

The new system/extension will not be eligible for FiTs since the new rules came into force in January 2016.

An important factor is the District Network Operator (DNO). They only allow 3.68kW export under 'self-commissioning'. Anymore than that will require prior approval by them. You will need to check your DNO!!!8217;s rules (which may be on their website). Their definition of 3.68kW will probably be:- an inverter smaller than 3.68kW, or limited to 3.68kW, or whose efficiency multiplied by 4kWp is 3.68kW or less.

For most properties (which have a single phase domestic supply) an application will have to be submitted to the DNO for prior approval, to exceed the 3.68kW limit. Your installer will need to complete a G83 stage 2 application, or a G59 application. Success will almost certainly depend on you (and your neighbours) having individual supplies to each property. If you share a loop with your neighbour(s) then the DNO are much more likely to decline. Also, the DNO will take into account the number of other SSEG!!!8217;s (small scale embedded generators) (PV, wind, hydro etc) in your vicinity that could potentially all be exporting at the same time.

You also need to contact your FITs provider just to get confirmation on their policies regarding extensions. I'd suggest doing it by e-mail (not phone) so you have some documented evidence.

If you are adding panels to an existing system (sharing an inverter and TGM) ask your FITs provider how they calculate the division of generated units. They will most likely apportion generation entirely on the installed capacity of the panels. Crucial !!!8211; if they take no account of orientation, and you are adding East panels to a South system, then when the generation is apportioned, some of the !!!8216;old!!!8217; system units, will end up as !!!8216;new!!!8217; system units, since in reality, the S system will outperform the E system per installed kWp.


11. Common terms and acronyms used on this site in conjunction with PV and renewables in general.

AGW = anthropogenic global warming
DECC = Department of Energy and Climate Change
DNO = District network operator
FITs = Feed in tariff scheme
Mono = Monocrystalline panels
NG = National Grid
O's = Oscars - slang abbreviation for kWh's/kWp to compare PV generation after taking install size into account
Poly = Polycrystalline panels
PV = Photovoltaic
RECs = Regional electricity companies (now just called 'electricity suppliers')
SP = solar panel (could be electrical (PV) or thermal (water))


12. FiT Degressions

FiT rates are to be reduced/degressed over time as the technology becomes cheaper, encouraging greater take up. The government has decided that PV FiT rates should be reviewed every 3 months (1st Jan, April, July & Oct). If installs during the qtr that just ended exceed 100MWp, then a 3.5% degression will be applied to the next but one qtr. So qtr 1 affects qtr 3, 2 affects 4 and so on.

If installs within a single qtr are even higher (150+MWp, 200+MWp or 250+MWp) then degressions of 7%, 14% and 28% can be applied.

If there have been no degressions triggered for 3 qtrs, then an automatic 3.5% degression will be applied, so we will, at the very least, see a 3.5% reduction every 9 months.

Latest: The installs in qtr2 were not high enough to trigger a degression in qtr4 (1/10/14). As this will take the non-degression period to 9 months we will see an automatic degression of 3.5% on 1/1/15 even if installs don't reach any of the degression levels [Edit 4/11/14 - installs in qtr3 just exceeded the 3.5% degression point of 100MWp with 103MWp of installs. So a 3.5% degression will take place.]. A degression of 3.5% will take the FiT rate for an upto 4kWp system to 13.88p/kWh.

Purely supposition, but installs seem to be growing, and if qtr4 installs are similar to qtr3, and exceed 100MWp, then we could see a further 3.5% degression at the start of qtr2 2015 - 1/4/15.

Latest (23/1/15) - PV installs in qtr4 2014 exceeded the 100MWp degression point, so the FiT rates for upto 4kWp (and 4-10kWp) will be degressed by a further 3.5% on 1/4/15. the new rate will be 13.39p/kWh.

Latest (2/5/15) - PV installs in qtr1 2015 exceeded the 100MWp degression point, so the FiT rates for upto 4kWp (and 4-10kWp) will be degressed by a further 3.5% on 1/7/15. The new rate will be 12.92p/kWh.

Latest (3/7/15) - awaiting OFGEM results for qtr 2 installs. Best bet is that they will again exceed the degression point, triggering a 3.5% cut on 1/10/15 to 12.47p. Results should be announced by late July.

Latest (1/8/15) - OFGEM have confirmed a FiT rate cut to 12.47p from 1/10/15.

It looks like the falling price of PV and 'constant' upcoming FiT reductions have created a level of demand consistently above the degression point.

Latest (30/10/15) - The degression point has been hit again, and the rate will be reduced to 12.03p on the 1st Jan 2016. HOWEVER we also await the outcome of the government review/consultation on FiT rates, that may reduce it down to 1.63p.


13. Basic consumer advice and protection.

For an introduction into consumer protection and rights, you can find information both general and PV specific on the RECC website:

There are also sections of the RECC code that potential PV'ers and concerned recent PV'ers may be interested in, such as section 5 'pre-sales activities'.

The RECC website also has a Top Tips section, worth listing (but links removed):

- Make sure you get at least three quotes before deciding to contract with a company.

- Only approach companies listed on the RECC website.

- Only approach companies certified by the Microgeneration Certification Scheme (MCS) for the relevant technology.

- Read our guidance carefully before you sign a contract or pay a deposit.

- Before you sign a contract or pay a deposit make sure you read and understand all the information carefully; ask for clarification if you don!!!8217;t.

- Never pay more than 25% of the contract price up front; check it will be protected.

- Never sign a contract if you are being offered a discount or pressurised in any way at all to sign it; this is illegal.

- Remember if you sign an order form or contract with a sales rep in your home you have the right to cancel the contract within 14 days from the date the goods are delivered to you.

- If you want the installation to start during the 14-day !!!8216;cancellation!!!8217; period you must give your express written consent; if you later cancel the contract you will have to pay for any work completed.

- Even if you do not sign an order form or contract with a sales rep in your home you still have the right to cancel the contract within 14 days from when you signed the contract; make sure you don!!!8217;t give up this right by signing a waiver.

- If you are being offered finance by the company you!!!8217;re contracting with remember you have 14 days from the date you receive the documentation from the finance provider to cancel the agreement without penalty.

- Check the Energy Saving Trust website for objective information and target prices.

- Check the DECC calculator for objective information about payments available under the Domestic Renewable Heat Incentive.

- Make sure any testimonials you rely on are genuine; contact the people yourself to check that they are, and that they were not paid for.

- Before you sign a contract or pay a deposit make sure the company gives you in writing a quote including a standard performance estimate specific to your property and a full, all-inclusive breakdown of what will be supplied.

- Before you sign a contract or pay a deposit make sure the company gives you in writing the standard terms and conditions that will form the contract

- Remember if you or the company make any changes to the contract make sure they are agreed in writing and part of the contract; if you are not happy with any changes you have the right to cancel the contract within 14 days with no penalty.

- Remember to send us your feedback once the job has been completed.


14. Inverter shutting down, reporting overvoltage / Grid voltage too high.

To ensure that the property uses generated electricity before mains electricity (gives preference to PV) the inverter monitors grid voltage and then produces AC electricity at a slightly higher voltage (1 or 2V's) than the mains.

Mains electricity should be at 230V within a tolerance of -6%/+10% (216V to 253V). If mains voltage gets close to the max, or exceeds it, then newer inverters are designed to switch off, to prevent them pushing the voltage even higher in a spiraling attempt to export electricity.

After a short time the inverter should attempt to re-start, but will continue to shutdown if mains voltage is still high.

If this keeps happening, then you need to contact your district network operator (DNO) as they have a responsibility to maintain voltage within the required limits. The Electricity Safety, Quality and Continuity Regulations 2002 - Section 27 (3) (b)

Some recent MSE threads:

Solar PV system fault developed

JamesMc69

Just to flag up - i have invested in panels on my roof but also invest in panels on other peoples roof via Abundance Generation

They offer "debenture" investments in projects that own and operate renewable energy power plants, you can invest from as little as £5 and know that your money is spread across multiple systems not just one!

I have completed two investments with them and been pretty happy with their service has anyone else tried them out?
JamesMc

coolcol1

My roof is not quite due South but SSW with no nearby trees or shadow,so im looking into Solar Panels,and well done "MSE"!
Ive just watched the "Ashadegreener" video that says they will install&supply for free,and any spare electicity produced is mine to use or feed back (FIT)
in the video the said they gain from a higher "FIT",this is there profit?
so is this a better option than me paying for my own install&supply? same difference without the outlay?

Thanks for any help on the question.:T

Martyn1981

Hiya coolcol1.

If you take a look at post #1 section 1, you'll see an explanation of the three income streams (FiT, export and leccy savings).

In the case of a rent a roof company (RaR) they would get the first two, you'd get the third.

Since you have a very good roof and location, a RaR may be an option, but consider this, if they would do it (even with perhaps lower install cost), then it must be a good investment, especially as they don't get the leccy savings, receive a lower FiT, pay admin, and pay tax.

So the million dollar question (perhaps £6k question) is can you finance it yourself out of savings, or at a very low rate. If you can, then self install will be a better option, if you can't, then your options are obviously limited .... today .... but might they change in the future.

Regarding incomes, this recent thread considers the returns:

https://forums.moneysavingexpert.com/discussion/4816680

Mart.

coolcol1

Again thanks,i have re read the earlier posts aswell.i take on board the points of selling but didn't think it was an issue,i will now look to save for a private install.
Also great link
highlighted this:
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