Your Questions About Solar Panel Installation

Richard asks…

Is it worth installing solar panels to your house?

I am led to believe that with the government scheme it has become attractive to invest in solar panels for your house. The installation costs are around £12,000 and I believe you only gain after about 25 or 30 years. Does anyone know if there are any calculations on cost and money saved over this period of time? It is certainly a long term investment. I would like to see the calcualtions before I spend this kind of money! Can anyone help? Thanks

ssadmin answers:

UK reply

We have installed solar panels that we own so know how the system works, as long as you are in Southern England, the further south you are the more money you make. Ideal position is facing due South, but SW – SE is OK. We are SSW.

“Free” panels are just that. The house owner gets the “free” use of electricity generated so you can save on your electric bill.
However to fully benefit you have to be careful when you use electricity. For example if you use a washing machine / dishwasher / tumble dryer at night when the panels aren't generating you don't/can't get free electricity! During a sunny day the panels might be generating 1kw but if you switch on a 2kw appliance you pay for the excess1kw needed to run the appliance.
So yes you will save some money on your electric bill but probably only 40% certainly not 100% of your bill.

The owner of the panels (i.e us!) is the one to benefit. We have a 4kWh system (biggest allowed under Government subsidy) and get paid +/-46p per kilowatt hour generated. This is guaranteed by the Government for 25 years!

We all buy electricity from the Power Companies at 12-14p unit so it is a huge subsidy – which the rest of you are paying – not the Government – one reason why bills are so expensive now!

As a generalisation the capital cost was £12,000 but I expect to earn +/- £1600 year. To put another way although I still buy some electricity (at night time for example) and all gas in effect we will be getting all our energy “for free” and about £600 extra cash in hand!

We have gas heating (now only for space heating) but now heat our water electrically with combination of offpeak electricity at night (5p/unit) and from our panels during the day.

If you have the cash BUY YOUR OWN as the scheme is Government guaranteed for 25 years!
In investment terms it is a 8-12% TAX FREE return for 25 years – you can't get anything like that anywhere else.

If you want more specific help email me and I can do the figures for your house and send some pictures of our installation, which took less than one day with minimal inconvenience.

Basically you have the panels on your roof, an inverter(converts the panels DC output to AC mains) in your loft, a conduit running down to your consumer unit and input meter. If it is carefully done all you can see is a conduit down your outside wall.

P.S. Even on dull days it still generates. Recently on a rainy grey overcast day we were still generating about 240w. So in January when it will be freezing with perhaps snow on the ground as long as the sun is shining we will be generating! It converts light to power – heat is not needed to make it work!

We have been running 8 weeks and generated 900kWh so far, that is about £400 to come from our Power Company!

Ken asks…

Anyone attend Solar Panel Installation Courses?

Hi, I am really interested in learning more about Solar Panel technology. What kind of courses are out there? Tech Schools? Community College Courses? What should I trust the most? Im a little skeptical when it comes to technical schools, not sure how to tell if they just want my money or not.
Also what does an installer have to learn and do as opposed to the engineer?
If anyone who had taken any courses at all, I would LOVE to hear what your experience was during and after the courses!

ssadmin answers:

Your on a roll to an exciting and rewarding field as solar energy will be the energy of the future, maybe not in our lifetime, but some huge advances will be made in just a few years. I'm sure some of the responders to your question will steer you in the right direction. Good Luck

Lizzie asks…

Solar Panel Installation?

Tell me complete installation I have one 150Ah battery two 80 watts solar panels about 30 meter DC wire i charge ontroller and 1000watt inverter. How i hook two solar panels to charge controller to battery then inverter?

ssadmin answers:

Wires from panels go to controller “input” terminals. Controller “DC battery” terminals to battery so that the controller will protect batteries and split power as required by demand to the inverter. “Output DC” on controller to inverter. “Output AC” or outlets on the inverter to AC appliances.

One thousand watts is not very much capacity. It will keep your computer running and a lamp to read by. It won't run major appliances. A hair dryer is typically 1500 watts and could not be run by this system.

Jenny asks…

Do you know any company which provide Solar Panel Installation traing?

Please suggest me except the below sites:

ssadmin answers:

The centre for alternative technology in Wales. It's been doing it for 40 years. They also teach lots of other Green energy, and they are a registered charity

David asks…

is my solar panel installation working correctly?

I have a 3.68 kW array with a samil power 3300 inverter but i've never seen more than 3.1 kW since it was installed in December last year. Today we have full sun and a clear blue sky and its noon – the array faces almost due south east, with a roof pitch of about 30 deg, so the sun is full on the array. The power reading is 2.7kW
Now the output of the cells is guaranteed within 90% for the first ten years. How can I tell if the array is out of spec?

ssadmin answers:

The figure for 3.1kW/3.68kW = 0.842. This is 15.8% low. I don't know exactly where your measurement is, but here are some points:

The rating is for a standard sun of 1000W/m^2 of sunlight. This is very close to what occurs in practice on a clear, cloudless day with exact pointing and the sun high in the sky (more than 50 or 60° above the horizon.

The power rating applies at a standard temperature of 25°C. The operating temperature is more like 60°C, so the power output is de-rated at the rate of -0.485% / °C = 17% typical. Make sure the panels are well ventilated. This is probably most of your losses.

There are losses in the wiring (not more than 2% according to some standards). The voltage drop is probably calculated with wire temperature of 75°C, so it will probably be slightly better than the standards imply.

The panels can be less than rated output by up to 5% in some sort of sample distribution.

Being off point by 30° in one axis will make this difference too. Check the shadow from a set square on the panel in both axes to see the point accuracy at the zenith (sun at its highest point). As the panel is south east, not south, this means the peak won't occur at the zenith, but some other time, which may or may not have an effect on the daily production (I am not sure your location, it seems not too far North of the tropic in the Northern hemisphere). Noon may or may not coincide with the sun's highest point, where you are in the time zone. You could look into this, but probably it is just something to accept.

The sun moves one degree in four minutes, so will be 1% down from a true point in 30 minutes (8 degrees off point).

With 3.1kW you are only 16% down when the expected temperature alone implies 17% low. This implies your panels were well pointed, wiring losses were low, and the temperature was less than expected, on the day that you saw the 3.1kW figure. I don't know whether the figure reported is; before or after the inverter, but the inverter can add losses of up to 10% maybe, depending on power, voltage and so on. You could see the 3.1kW figure after the inverter if the panels were cool enough. Inverters are often specified for efficiency at their rated power, which is probably also the best efficiency operation.

Your current reading of 2.7kW is 73.4%, or 26.6% low. This is an additional 10% loss from that expected due to temperature alone. It sounds reasonable if after the inverter, but if before, I would suspect:
shading (even of 1 cell in a series string)
dust, a bad day (not full sun clear sky, clean air)
off point by 25 degrees in one axis, or less in two axes..
It is likely a combination of several of these. Be very careful if you decide to clean panels, as high voltage is involved. Check how to do it safely. I wouldn't bother, just wait for rain.

The link below shows sample specifications. The output power temperature co-efficient is basically the same for all silicon panels as far as I know.

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