Make Energy At Home

I am sure that LED, ‘zoned’ lighting is a great solution to low voltage (12 volt) lighting focused on a task or specific area. It has taken some time for LED bulb technology to emerge and they are still expensive and often manufactured to run on a 240 volt system rather than a 12 volt. I tend to think that if you want to go ‘grid free’ for lighting at least, that a 12 volt system is desirable. It is much more efficient in terms of using solar panels or small windmills to power a 12 volt battery. I have a garage workshop and a caravan office that could both benefit from using free energy for lighting.

So I decided to start experimenting. Firstly I stripped down 10 solar garden lights and rewired the LEDs so they came inside the house, while the collectors stayed on the roof. In collections of three LEDs with a small reflector they gave just enough light to read by if you held the book directly under the light. It was quite a strain. The crap ‘rechargeable’ batteries didn’t even last a year.

Then it occured to me that I could possibly use some of the electrical transformers sitting in my cupboard, from broken or worn out electrical items, to power some LED lights. This might give battery technology a chance to catch up while I played with the lights.

LED lights with transformer

Rather than paying £25 an LED bulb, there were some stick-on, battery-operated, cupboard lights available in the store at 3 for £5. These, rather extravagantly, use 3, 1.5 volt, AA size batteries each. So I took out the batteries and re-used them elsewhere and wired three of these little cupboard lights together in series to make some recessed lights for the kitchen and added a 4.5 volt transformer from my collection. Again the result was more akin to safety or emergency lighting, but was certainly brighter than the first attempt. I needed something with more LED’s.

LED caravan lights and transformer

Then I found a £2.50 ‘camping light’ with 24 LEDs, powered by 4, 1.5 volt, AA size batteries (it came without batteries). To accompany this one I had a 6 volt transformer and wired it into the battery compartment. Now I was achieving some powerful light, easily enough to work by. In addition this light had options for 4 on 20 off, 20 on 4 off, or all on. I noticed that the transformer got hot very quickly and it wasn’t long before the LEDs started blowing. Each time one LED blew the light got brighter and the other bulbs started blowing more quickly.

This light was evidently a fire hazard and I realised that the bit of information that had always eluded me, concerning volts and amps, and their relationships, was probably something I needed to understand, especially if I intended to make solar panels and windmills.

We have decided, mainly due to the new UK Feed In Tarrifs, to install Solar PV panels on the roof. Now I have recently heard PV solar panels described as ‘Green Bling’ on Radio 4. So I have just had a visit from ****, on behalf of PV ***** UK Ltd, to give me an estimate for fitting PV solar panels to the roof.

polycrystalline PV cell

Now £18,000 is a lot of money. I don’t have it but my partner does have some savings sitting in a building society earning something like 3% per, at a guess. This company are based in Wales and although the UK government has finished grants for installing solar panels, they are due to increase the tarrif for domestic microgenerators from April 2010. For a very short time, thanks to the Welsh Assembly, they can knock £2,500 off the total, so that’s £15,500.

An estimated return on these panels, from sell back to the grid, of 22 solar panels harvesting 4620 kWh/year is estimated by the salesman at £1960 per annum. This gives a payback time of about 8 years. This amount does not include an insurance against energy price rises for the life of the panels (estimated at 25 years) because the sell-back tarrif will equal any price rises.

There are also variables in our favour:

• an ideal, large,  south-facing roof without shade
• the fact that we are in Cornwall giving longer daylight hours that the average the estimate is based on
• the fact that we are very low energy users decreases payback time
• the amount of lunar light absorbtion is not estimated but can reach saturation when it is full
• the potential to add other panels and devices to the inverter

These may well decrease the payback time substantially.

Over the life of the panels – say a conservative 20 years (although this is rated at 25) @ £1960 per annum, the estimated payback (not accounting for price changes) would be £39,200, a return of £23,700, payable by quarterly cheque from the electricity company during the life of the panels. (Not to mention the 2/3 reduction of the electricity bills adding £2400 in savings over 20 years)

Now a 3% return from the building society on £15,500, is £465 a year. Over 20 years this amounts to £9,300 (I don’t know how to do this cumulatively but I am advised it works out at a lot more).

Even a 7% return, of £1085 a year would bring in £21,700, slightly less than these panels that may well have a longer lifetime and are likely to ‘harvest’ more than estimated.

Even over just 10 years the payback after (paying for the panels in 8 years)  will be 2 years @£1960 per annum = £3920

Ten years at 3% from the building society will be slightly more @ £4650, but not when you factor in the savings on our electricity bills over 10 years (again with the price a constant – most unlikely) estimated at £1200 (+ £3920=total £5120).

So given that we have the benefits of our own localised power system and a personal reduction in carbon, does this look like ‘Green Bling’? Are these figures realistic? It looks to me that PV panels return around 8% which isn’t far off 3 times what one get from a building society – and its tax free !

Have arranged for another rep to visit next week.

We checked with the North Cornwall planning department in Bodmin to see if we needed to get planning permission from them for the panels. A strange letter came back with what seemed like irrelevant dates and other nonsense saying that we would need permission.

My partner Sarah decided to question this via our MP while I got on with their inflexible forms. For example all the trees on and around the property had to be listed on a map. One of the maps had to show at least 2 named roads and be at an obscure scale – 1:2500 which was only available from their website for an additional charge of £20 over the £150 fee. On downloading their map to look at – there were no named roads.

Plan of Cottage

I spent a day doing this and one of the companies who quoted for our panels were very useful, generous in fact with their time and information. Days / weeks even trundled by until a phone call came back from the North Cornwall Planning Department saying that they had made a mistake and we didn’t need planning permission. Shortly followed by another letter from them via our MP saying that we had to write to them to clarify whether or not we would need planning permission.

In the meantime we got down to deciding just who was going to supply the panels. Company 1 ‘P/S’ were the locally established company for panels in Cornwall but their price was £3000 more than the others. Company 2 – ‘C/E’ had visited by then to measure up for an onsite estimate and found they could only fit 9 panels, returning an estimate for that from their ‘internal’ roof measurements.

romag solar panels

sharp solar panels

So I decided I had to check this for myself and drew up some scale plans to compare the panels of company 3 ‘R/E’, whose panels were larger but claimed they could fit 11 with company 2 ‘C/E’ .

The other 2 companies had supplied standardised estimates, Company 4 ‘M/G’ had a comparable quote, more expensive than 2 and 3 but less than 1, and company 5 claimed they would fit 22 panels up there – with an estimate we didn’t believe. In fact I think this one was a lone salesman who visited hoping to cream a profit as a middleman.

comparative table

Company 2 ‘C/E’ had now supplied 3 quotes for 12, 9 and 11 panels (based on my drawings) and had failed to answer a simple question about wind factors. Company 3 ‘R/E’ was the one who helped us with planning advice, and also the only one who got the estimate ‘right’ first time. Their panel array also revealed about 20% more energy than company 2. They had also provided a photographic ‘visualisation’.

Cottage with panels

So we made our choice with company 3 ‘R/E’, who had also invited me out on an installation in Truro to get the hang of things. We would need to pay 12.5% up front, a returnable deposit to get on the list for an inverter. Then when North Cornwall Planning Department was resolved we would pay another 12.5%, then 70% before the installation with 5% on completion.

Sharp solar panels installed on a roof

We sent another letter to North Cornwall Planning Department asking clarification of what it was they actually wanted us to do, with an outline proposal including the images shown here.

Before long we had five estimates from various companies. I have abbreviated their names.

relative costs for PV panels

There was quite a difference and ‘payback times varied between 8 and 12 years before the panels went into ‘profit’.

Company 1 had a high payback on the tariff but seemed to be using ‘optimistic’ figures based on Cornish sun rather than the national average. Their array was also £3000 more expensive, although they seemed most professional and certainly knew what they were talking about. They looked in the attic and got on the roof with tape measures as you might expect for a good estimate. They have a lot of experience with about 100 installations

Company 2 haven’t visited as yet and the estimate was by email. They are just in the process of getting PV status from an MCS inspection. To be fair though they do have experience with other types of solar panels and renewable energy installations.

Company 3 were very interesting. They are a local (Cornish) company with about 20 PV installations done, who operate as a ‘not for profit’ business. They have educational and community aspects to their business and visited to make a proper estimate of the work concerned. They were also most helpful when we realised we were going to have to go through planning permission – an additional £150 charge and some form filling and image creation.

Company 4 had a standard pricing PDF download which I got from the internet, although I did talk with them on the phone also.

Company 5 were the first to visit. The salesman didn’t measure up the roof or look in the attic for placing the inverter. His assessment of 22 panels on the roof was entirely unrealistic.

Company 3 also offered to create an image of what the solar panels would look like on our roof if I sent them an image of it. Here is our roof without the PV panels.

our house without PV panels

The disparity between the prices of home made panels and manufactured panels is quite wide.

Small Solar Panel

Home-made can be quite cheap if you can get the parts, and manufactured panels still seem very expensive, even given the new tarrif.  It is worth experimenting with pv panels at a lower scale for me to understand some pretty basic things like the difference between watts and volts and amps and all that. With a 2% mark for my Physics mock  ‘O’ level I was not allowed to take the ‘O’ level exam and scraped by with a General Science ‘O’ level. My Physics report read: “A hopeless Case , I fear”.

So I want to start pretty basic with a solar panel educational ‘kit’. This is made so that I can experiment with arrays of the panel in series and in parallel – with different results on the volts and amps. It consists of eight small cells with plus and minus terminals that you can arrange in a box and then make a circuit with small strips of metal.

Solar Cells, Radio and Fan

To power the fan it takes 1.6 volts and 100mA, a mixture of 4 cells each in parallel and series.

To charge the radio it is 3.2 volts and 100mA – which is 8 cells in series.

In short it is the device that you are running that determines the output of the solar panel and why one is meant to determine this before building a panel.

In order to experiment with output variables  I have chosen a number of devices that can be solar charged with a small panel like this.

Solar Options for Portable Devices

This useful device, a multiple, portable solar charger is available commercially in the form of a ‘Freeloader’. It has multiple lead attachments for many rechargeable devices. The solar panels are detachable so that you can carry around a spare charge for your phone, mp3 player or camera. The charger also plug into USB’s and charges itself when the host machine is on.

The great thing about a portable solar charger is that allows you to ‘graze’ on sunlight for free energy. Here’s a picture of my Freeloader operating in Cuba !

My Freeloader in Cuba

On 1st February 2010 The Government confirmed the new feed-in tariffs coming into being on 1st April 2010.

A typical 2.5kW photovoltaic solar system, such as the one we are looking at, will harvest a payment of 41.3p per KWh, paid whether the electricity it generates is used by the homeowner or exported to the grid. An additional 3p per kWh is made for each unit exported to the grid in retro-fitted properties. New-build properties get a lower tariff of 36.1p per kWh.

It is not quite clear how the payments are made yet but the gossip is that it will be paid quarterly by the electricity company. Imagine that – getting a cheque instead of an energy bill ! Energy used at home while the panels are generating reduce the size of your energy bill by a half or two-thirds.

These tariff payments are index-linked and guaranteed for 25 years. This is extremely attractive because it creates a 25 year insurance against energy price rises which average out at 8% a year based on the last 10 years. Projections show that from 2015 onwards that the country will not have enough energy to meet demands which may result in 1970’s style power cuts. With the installation of a ‘back-up’ system of some kind it should be possible for a microgenerator to avoid these altogether.

A 2.5kW system should generate payments of more than £1000 per year, tax-free. The payback on the investment will be around 11 years. This gives an overall return (in theory) on the investment of 8% - better than most bank accounts and building societies – even ISAs.

For the third estimate, two gentlemen arrived from Penzance and measured the roof for the solar array.

Ethically I much preferred this company and really valued where they were coming from. Members of the Renewable Energy Assurance Scheme, they are a ‘not for profit’ company with values that allow them to return money the company makes to ‘the community’. They have done about 20 solar installations, some quite large and some ‘quirky’. I always love quirky.

They run renewable energy education sessions and are setting up community schemes to help people in energy poverty – which is when more than 10% of your income goes on heating your home. We talked about the coming flood of installations and the problems that a company describing itself as ‘not for profit’ has with funding.

I was also impressed with their co-operative structure – all the workers are company owners, and their follow-up claim that they keep an ongoing relationship with customers to help them get the most out of their investment.

They assured me they could beat the other two estimates I had been given. I was already persuaded. Mind you its not really my choice because the money from this investment is coming from my partner – I just get to share in lower electricity bills.

The second estimate revealed the first to be rather optimistic. Rather than a 3.85 kw system with 22 panels creating 4620kW/year, this company ‘plug*******sun’ recommended a smaller system of 12 panels on one end of the roof only, avoiding the shadows from the beech trees that fall on the roof between September and May, starting about 2pm.

They revealed an additional factor I had not realised. If shadow falls on any one of the panels the overall efficiency of the whole system takes a drop because the panels are wired in series.

This array would be a 2.5kW system. They actually measured the practical roof space at about 18sq.m. with a total install cost of £12,500 (not including the scaffolding). Payback time on this would fall between 10 and 11 years and would reveal an income after payback of about £20,882 over 25 years. They agreed that on average the payback on investment from a solar array is about 8% overall given contemporary figures.

They also took a look at one of the other roof spaces we have, a flat garage roof and said there was room for another 12 slanted panels there. This is a possibility for later and would mean installing another inverter because the inverters run best under pressure, ie they need a load close to the level of the panel array to achieve maximum efficiency. The possibility of plugging home-made panels into the system is not practical because it is the panels that have to be approved.