Monday, 24 February 2014

Going 'a shade greener'?

There is a company, located not too far from me, who specialise in photovoltaic installations, and trade under the name 'A Shade Greener'

I am somewhat curious about this. I have for a long time liked the idea of a solar power installation. In fact, I already have a small solar panel used for charging a 7Ahr SLAB, and using that to run small loads such as my weather satellite receiver, which now is very little used (hmmm, theres a thought - I dont use it because I no longer have the antenna, but I might try it on the discone!)

A shade greeners business model seems good, if a little cheeky. Essentially, what they are offering is a totally free installation. Yes, totally free. So, whats the catch? They say there isnt one, and in many ways thats true. It does seem a pretty risk free plan. Basically, you sign to a 25yr lease. They rent your south facing roofspace for 25yr, during which time, they also maintain the system for free. As the consumer, you get the benefit of the free electricity it generates. All sound too good to be true so far?

Well, ok then, heres the deal. Yes you get free electricity, but only during the time the panels are generating. When the panels are not productive, ie when its nighttime or bad weather/thick cloud, you buy your power from the grid as usual. So the savings you can make depend entirely on how much of the free power you can use, during the day, without going above the generated amount. This is where the company's business plan starts working. Most people are not about during the day when the power is being generated. Also, if they are, its likely that less power is used anyway, as lighting and heating are often not required. So, because the home owner isnt using all the generated power, the company makes its money on the payments from government under the FiTs scheme, which pays for microgeneration to feed into the grid, and it seems pays well.

So, how to get the most from a free installation? Its all down to how much of the free power you can use at the time. The usual technique is to change your habits. Run the dishwasher, hoover, washing machine etc, during the day, and in series, not parallel. Running them all together will go above the generated load and cause you to have to buy from the grid. Using them one after the other can make the most of the available solar power.

So also, running a radio station during the day (reasonably convenient for me) uses free power, unless you go over in the transmission peaks! But what about evening or night operations?

It all comes down then, to storage! I am reasonably lucky in that I can occasionally lay my hands on surplus but still reasonably usable large sealed lead acid batteries, ex of UPS systems. By using the free power from a solar array to charge a bank of large SLABs, that power is then available to run the radio station and any other suitable loads later.

Its unlikely that such a system could be built for a reasonable cost that would run such kit as washing machines, but using a suitable inverter it could run a telly, or perhaps the fridge? Also, my kitchen and bathroom lighting is already 12v LED. By replacing more lighting with LED technologies, battery stored power could be convenient.

I have on order a roll of this stuff
this is flexible LED lighting. 5m long, extendable, and comprising about 300 white LEDs. It can be used by sticking it to a surface, say the underside of a shelf on the radio desk, or on the top of a picture rail. Im going to try this out as a way to replace mains powered lighting in my shack and workshop. I will then look at the use of solar charged batteries for running this.

The company's free system doesnt have many disadvantages, but its not easy for the home owner to actually make much of a saving on their power bill, likewise the lease timeframe is somewhat excessive

A Shade Greener free photovoltaic installation
Pros -
Free Installation
Free maintenance
'Some' free power

Cons -
Savings available to home owner are vastly lower than profit available to company
25yr lease is excessive. 10-15yr would be more acceptable
Array remains company property after lease expiry. Array passing to consumer ownership would be preferable 
No bidirectional energy monitoring. I would want to see what im feeding to grid.
No specs regarding RFI/EMC of installation

That last con is of particular concern. The chargers/inverters etc used would have to be properly filtered, in effect 'silent' at radio frequencies. I would not tolerate ANY increase in noise floor from the system.

Now, I know my roof is suitable, even without them doing a survey (hey, you dont study Environmental Science and Renewable Energy without being able to work these things out). I could buy my own installation, in which case I get all the free power, plus the feed in tarif. But heres the reason this company can do this - I dont have the money for that!

So its something im interested in, and might consider. Of course, by blogging about it, ive effectively given A Shade Greener some free advertising! Perhaps they will read this! If so, then they are welcome to contact me to discuss providing me with a 'showcase' installation, tuned somewhat more towards my requirements. Im sure its unlikely they have an amateur radio station in their installation portfolio, and even more unlikely they have a battery storage and comprehensive LED lighting installation. Maybe they would like to go with my plan as a live demo of what solar can do?

No comments: