Solar PV installation, Harpenden, Herts. 2.22kWp system

Having been interested in domestic energy generation for several years, we’ve been watching developments in the various technologies over this time. The wind technologies for the domestic market never lived up to expectations. Our hot water is obtained through a gas combi boiler so solar hot water wouldn’t be financially viable. As for PV, the recent government FiT scheme suddenly made it very attractive. So we started looking into it. We did our research on systems, manufacturers, technologies, searched websites for indicative prices and contacted several installation companies for a chat.

At this point I must warn prospective PV clients about the selling techniques some companies employ. As knowledge grows about domestic PV and the government’s incentives, companies are springing up at a very swift rate to jump on the band wagon. There’s companies sending out reps with little or no knowledge of the technicals, and operating the ‘double glazing’ sales/marketing techniques whereby the price drops 40% over the course of their visit! If you come across one of these techniques, DON’T sign up!! The reputable companies will provide an indicative quote by phone or email and if you’re interested in taking it further, they’ll send out a technical bod for a site visit. The site visit will confirm your property’s orientation, the roof construction, the cable routing, the siting of the electronic boxes, and confirm (or modify) the indicative figures of generation (units and cost benefits) that you’ll have received in your provisional quote. It’s worth bearing in mind that any indicative figures given to you should have been based on the government’s SAP figures, which are generally conservative.

The company we chose was Spirit Solar, based in Reading. They were professional, thorough, knowledgeable and above all fun to deal with. They shared the ‘buzz’ and excitement of ‘green’ energy, which made the whole experience even more pleasurable. The installation went without a hitch and we were generating juice by 4pm on the second day. We do, however, live in a bungalow which made the install relatively easy. There was no need for extra scaffolding and we had given thought ourselves to the cable routing to make things easier.

We’re now one week on from commissioning and all the facts and figures we worked out (and those we were quoted in quotes etc) appear to be on target as expected. And we can’t stop watching the Sunny Beam wireless generation meter!

We have 12 x 185kWp Yingli poly panels with a SMA Sunny Boy 2500 inverter, providing a 2.22kWp system. We face due south-west with no shading. The expected annual output is around 1,750kW – about half of our annual electricity usage. System cost was £10,500.

We anticipate an annual return of around £900 – a combination of Feed-in, export units and the saving on our electricity bill. Guaranteed for the next 25 years, and tax-free!

Steve Bryant. Aug 2010.


Alan Harper

September 13, 2010

Your figures do not make sense.
For a start the “expected annual output” should be stated as kWh because it is an ENERGY measurement term. The “strength” of Power generated is measured in kW.
From your figures, if we assume it should be 1,750 kWh (1750 Units) of energy supplied over a year, this ONLY amounts to a constant average power generation of 1750/8760 kW = 0.199 kW. Quite pathetic really and the only reason people are interested is because the Government supplies Grants and every other electricity bill payer finances what you get paid for your FiT units. This subsidy is so well camouflaged by the Government and is really a Robin Hood policy in REVERSE. Rob the poor to pay the RICH who can afford to finance a home installation.
It is called GREED.
As more people join the scheme, there will be fewer “ordinary” bill payers to finance your devious gains so you could, in the long run end up severely out of pocket once the “ordinary” bill payers revolt as will happen soon and the money dries up.
Remember, the “Green” religion all started with wind, and domestic generation with that has proven a farce (Refer Energy Saving Trust Report).
You will ALWAYS need to be coupled into the grid because there is no way your system will be able to cope with the kW power level of generation you will require for cooking or heating. A normal oven has about 4.5 to 6.5 kW worth of elements and your hob will have 1 x 2.5kW with at least 2 x 1.5kW elements. Then you will want a cup of tea and the element in that kettle is rated at a minimum of 2.5kW. Accordingly, you state a Power Output of 2.2kW peak i.e the maximum. These elements are designed to work with a voltage of 240-250vAC. So how efficient is the CONverter/inverter? It is a DC [PV] to AC [Mains] CONversion.

Angus Roberts

January 30, 2011

This reply is really to provide an alternative approach to the idea of small scale generation to that very negative view supplied in the above post.

To start with, as correctly stated above, the 1750kWh annual energy generated by the solar photovoltaic installation will provide approximately half of the annual demand of a typical domestic property. As electricity has very intense carbon emissions, the overal carbon emissions negated by the use of the PV panels is significant.

Secondly the above calculation is not correct as PV panels do not provide electricity when the sun is down. therefore the annual hours of generation should not be taken as 8760, they should be taken as 4486 hours which equates to 390 W average running load which is significant.

The third point is that PV power is a very useful technology to be utilised for offgrid installations as it requires minimal maintenance, will provide power everyday, and the energy provided can be stored through batteries or via a thermal store by generating hot water for later use. Therefore the statement that it will always need to be coupled to the grid is simply not true.

However as stated, peak energy demands will be a problem but a little thought will always get you through. Why not use a gas hob for boiling water, a gas oven or use wood to provide both.

The simple idea of the green religion is not true. It is true that domestic wind turbines in built up areas do not work. However no one ever said they did. All the main reports (energy savings trust included) have advised that prior to purchasing and installing a wind turbine, the wind resource must be checked. An average wind speed of less than 5m/s would make the proposed installation unviable.

Please note that the governments proposal is designed to make renewable energy a viable investment with rates of returns much better than the bank. Therefore if you cant afford the upfront costs, I would urge you to review the options available to borrow the money as 7% pay back is favourable for a bank loan.

Oh and lastly I would advise you read and understand a subject more prior to writing a damning opinion which is factually incorrect.


December 31, 2011

just wondered how did the system perform ?
has it was installed in 2010 ?