Getting Started in the big Solar
The great thing about starting with this solar challenge is
you do have a number of options, you can have a complete system
with all the bells and whistles or you can simply put a toe
in the water with a very basic system and see how it works
out for you, below we can look at some of the choices available
A complete professional solar system installed *On Grid with
hot water providing electricity and up to 50% of your hot
water energy. **Approximate budget needed £10,000 -
A complete professional solar system installed *Off
Grid with hot water providing electricity and up to 50% of
your hot water energy. **Approximate budget needed £8,000
A complete professional solar system installed *On Grid. **Approximate
budget needed £6,000 - £9,000
A complete professional solar system installed *Off Grid.
**Approximate budget needed £4,000 - £7,000
A complete professional solar hot water system providing up
to 50% of your hot water energy. **Approximate budget needed
£5,000 - £9,000
One or two solar panels for a partial energy saving exercise.
**Approximate budget needed £500 - £3,000
One or two solar panels for an outhouse, extension or conservatory.
**Approximate budget needed £500 - £2,000
One or two solar panels for a workshop, garage, shed or greenhouse.
**Approximate budget needed £300 - £700
For the smaller partial systems in extensions, conservatories,
outhouses, workshops, sheds and greenhouses it is possible
to do the job yourself providing you are suitably qualified
and have good practical skills. Do not however be fooled into
thinking that just because these systems are 12/24volt systems
that they are not dangerous, because they can be far more
dangerous than a conventional electrical installation. If
in any doubt as to your own ability consult a qualified electrician,
this does not mean that you cannot make a saving as you can
still work with your qualified electrician in managing your
installation. There is a lot you can do with the right practical
approach, this website will in any event give you a good idea
as to how your system works and will only add to the job at
hand even if you are having it professionally done.
* On Grid means being
connected to the mains and selling any overflow power to the
electricity companies, whereas Off Grid is not having this
This figure is offered only as a very rough guide as property
sizes and location can make very big differences.
- Do not however be fooled into thinking that just because
these systems are 12/24volt systems that they are not dangerous
because they can be far more dangerous than a conventional
electrical installation. Please read the various pages on
care and maintenance carefully and take note of the precautions
necessary in the solar challenge.
If you are having your system professionally
installed then you will have a consultation and specification
supplied by your chosen supplier. But if you are doing the
job yourself or with a qualified electrician you need to look
at what your needs are and do some very basic calculations.
Example Solar System and
the working out
Lets look at a basic system for a
1 roomed extension with two table lamps a TV and receiver
(all 12 volts appliances). You can of course run your normal
household appliances but you will need an inverter and the
figures below would have to be adjusted for the extra power
The first consideration is the ability
to be able to mount a solar panel facing south with as much
uninterrupted sunshine as possible. Next we must consider
the housing for the storage of leisure batteries, this could
be in a sound waterproof workshop, garage or similar dry storage
the looking after your leisure batteries page.
Having settled on those two points the next thing is to do
some sums to determine the solar panel size and the number
of batteries required.
Lets look at the power requirement in detail (these are all
examples only - check the labels on your own appliances):
We can use some Ohms
Law here to help us work things out!
|Table lamp 12 volts
|Table lamp 12 volts
||37 Ah per day
To be able to service this energy
requirement it would be advisable to have two 85-110 amp hour
leisure batteries. Although the figures indicate that one
battery would have enough standby power, you would be running
a single battery down to a very low point where permanent
damage could be done as batteries do not like being run down
as low as to 50% of charge. So two batteries would be best
so they can both share the load. This way the batteries should
have a very long life. See
looking after your leisure batteries.
Now lets look at the solar panel(s)
size necessary to maintain the correct level of charge per
day i.e. replacing the 37 Ah's we have taken out and having
enough extra power to keep the batteries fully charged even
on the darkest of days. For the sake of this example I am
assuming that during the darkest months of mid winter we only
get 4-5 hours of good collectable light. Therefore to replace
this energy we would need two 125 w solar panels which would
each supply 20.5 Amps per day during the 4-5 mid winter hours
equalling around 41 amps in total for the two panels. This
covers our 37 Ah per day with a bit extra to help keep the
batteries topped right up to the top. The sizes of the solar
panel would be approximately 1500 x 700 x 35 each. This equally
could be achieved by having multiples of smaller panels to
the same value of 250 w output, this option often makes it
possible to fit arrangements of panel sizes into a given space.
It is very important to us all that the panel arrangement
looks neat and well balanced from an aesthetic point of view
as the panels are often viewable by neighbours who may have
it as their only view all day.
Here is the working out in
Energy requirement = 37 Amp hours per day
Battery storage requirement = 2 x
85-110 AH batteries
Solar panel(s) = 2 x 125 watts giving
41 Amps per day (winter hours)
It is worth pointing out at this stage that for a very large
part of the year the above system would be producing far in
excess power than we actually need, so additional appliances
can be added as long as you monitor and manage your batteries
carefully during the mid winter days. See
the batteries page. Managing your energy needs is largely
about storage and storage means batteries. The more batteries
you have the more disposable power you have and the longer
you can continue with your energy requirement level on the
worst light level days. Your system should be specified to
always have some reserve energy, only having enough energy
to just about skim through can cost you dearly later in terms
of replacement batteries.
Buying 12 volt Appliances:
You can purchase a good range of table lights, plugs, sockets
and electrical fittings from sailing chandlers and caravan/motorhome
accessory showrooms, you can also convert your existing lamps
by changing the mains plug to a 12 volt plug and putting a
12 volt bulb and new bulb holder in place. There are types
of bulb we are all familiar with that are 12volts and screw
into the edison type bulb holder.
IMPORTANT - You MUST
of course still change the 13 amp plug for a 12 volt plug.
Always read all of the pages on this website before starting
a solar system installation - especially the solar
Other pages to help you
with the installation are:-
To communicate with us over
technical issues please use the Solar
Chat Forum, also take a look at the Solar
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Warming - it's why we are making changes to our way of life!
David Bellamy has a very interesting article on global warming
where he gives another point of view, Read