[tog] UPS for my House / Off Grid System

Noel Bourke cros13 at cros13.net
Thu Apr 16 11:39:26 CEST 2015


Apologies in advance for the embedded images.

On 16 April 2015 at 09:31, Daniel Cussen <dan at post.com> wrote:

> I have worked with wind, solar and diesel generation systems.
>
> You have not really stated your aims or objectives. Also a budget
> would be helpful.
>

+1


>
> If you aim is to save money insulation and energy reduction is
> probably a much better value proposition.
>

Depends, in the average Irish house.


>
> One key metric is how many years until it breaks even, and what is the
> life of the system. If you cannot calculate that then you are not
> basing your decisions on facts but marketing bull.
>

In Solar PV the inverter is usually the first thing to go. Expect 10-15
life.

>
> In my opinion most home scale wind is not great quality, can be noisy,
> and as said would have safety/insurance problems. Any wind system I
> have seen has broken and been fixed a few times. If it is high up that
> means cranes or a tilt over system.
>

Wind isn't economically viable, cost per KW is insane due to the high price
of turbines and groundworks.

>
> Batteries are very expensive and not a good idea when mains
> electricity is available. The numbers just do not stack up.
>

Sure... for the older systems. Lithium Ion battery cells from the EV
industry are changing that.Tesla's battery is due to be $200/kWh (based on
the pricing during the pilot.
A 50kWh pack will hold enough power to

>
> Solar Electric (PV) panels are very low maintenance but they are very
> expensive initially and don't give out much energy to power anything
> substantial. they would be fine for say LED lighting, TV, but they
> won't ever power water heating, washing machine, kettle. A 50W panel
> would give out something like 10W during daytime on an average Irish
> day. That said is there anyone home during daytime, and what is your
> energy draw during the middle of the day?
>

PV panel prices are astonishingly low compared to even 18 months ago. The
economics of this one have changed rapidly.
On a 255W Samsung panel, south facing roof in the midlands average
production over 365 days puts the number close to 100W.
Ireland south of the M7 gets insolation numbers similar to northern bavaria.

Panasonic's solar calculator is one of the better ones:
http://eu-solar.panasonic.net/en/service/solar-calculator/

Price per watt of PV:


Or compared to other major grid energy sources:

Source: Bernstein Research. Data: EIA, CIA, World Bank, Bernstein analysis



> One system I saw installed, was a small wind turbine that connected
> directly to a the electricity wiring in the home. This used no
> batteries and had it's own inverter. Basically while the wind blew it
> helped reduce you electricity bill. It needed no batteries and was
> fairly self contained. However putting up a pole, turbine and
> connecting it to your fuse board is still a big job.
>

You can do that, A good solar inverter will cost around €600-800 euro.
4.1KW of high quality panels should cost ~€2,200 - €2,500.
2kWh storage systems start at €1,800 including charge controller.

However with the loss of the feed in tariff, unless the electricity use in
the house tracks the production closely, PV in Ireland needs storage to be
economical.
There are 15 255W panel at my parents place in Tipp. Their daytime usage
averages under 200W while production averages 1200W.
Nighttime use for charging EVs can exceed 15KW.

What even 2kWh of storage can provide is a bridge to cover usage until the
night rate electricity kicks in at 23:00 - 00:00.


> The SEAI is the independent government body that gives advice, and
> real world numbers for these systems, but for a start what is the
> energy rating of your home?
>

+1. And definately get an OWL network energy monitor. Measure your use
before considering spending any money.


>
> http://www.seai.ie/Renewables/Renewable_Energy_for_the_Homeowner/
> Grants, subsidy and hype are a big part of the industry.
>

Grants are almost non-existent. Most of the Irish companies just rip people
off.

On 16 April 2015 at 09:31, Daniel Cussen <dan at post.com> wrote:

> I have worked with wind, solar and diesel generation systems.
>
> You have not really stated your aims or objectives. Also a budget
> would be helpful.
>
> If you aim is to save money insulation and energy reduction is
> probably a much better value proposition.
>
> One key metric is how many years until it breaks even, and what is the
> life of the system. If you cannot calculate that then you are not
> basing your decisions on facts but marketing bull.
>
> In my opinion most home scale wind is not great quality, can be noisy,
> and as said would have safety/insurance problems. Any wind system I
> have seen has broken and been fixed a few times. If it is high up that
> means cranes or a tilt over system.
>
> Batteries are very expensive and not a good idea when mains
> electricity is available. The numbers just do not stack up.
>
> Solar Electric (PV) panels are very low maintenance but they are very
> expensive initially and don't give out much energy to power anything
> substantial. they would be fine for say LED lighting, TV, but they
> won't ever power water heating, washing machine, kettle. A 50W panel
> would give out something like 10W during daytime on an average Irish
> day. That said is there anyone home during daytime, and what is your
> energy draw during the middle of the day?
>
> One system I saw installed, was a small wind turbine that connected
> directly to a the electricity wiring in the home. This used no
> batteries and had it's own inverter. Basically while the wind blew it
> helped reduce you electricity bill. It needed no batteries and was
> fairly self contained. However putting up a pole, turbine and
> connecting it to your fuse board is still a big job.
>
> The SEAI is the independent government body that gives advice, and
> real world numbers for these systems, but for a start what is the
> energy rating of your home?
>
> http://www.seai.ie/Renewables/Renewable_Energy_for_the_Homeowner/
> Grants, subsidy and hype are a big part of the industry.
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