Looking for some Solar guidance and advice - batteries & system

[Solarminer]

Dear All and greetings from London, UK

I am a newbie and hoping to get some much needed help from the experienced and engineer minded members. ANY help would be greatly appreciated.

I am in the UK, London, so sun is not a generous commodity here and also relative to measurements/currencies it may be different to any advice/specs offered from the US but i'll do my best to understand, please imagine your explaining solar power/energy/ratings/etc to a 10 year old

I have been interested in solar/alternative power for sometime, I am not in the position to have my whole house switched but as a hobbyist I would love to build a successful small off grid system.

I would like to power 2 units, each unit is 360-400w draw and they will run 24hrs, 7 days a week.

I have an unhindered fully South Facing roof and would ultimately put the panels on this part of the roof.

I already have 2 Sharp solar panels, please see the specs of these here: http://www.sharp.eu/cps/rde/xbcr/doc...48_1109_eu.pdf

I have a 30Ah charge controller, a 1000w/2000w peak power pure sine DC12V- AC240V inverter.

What batteries would I need?

Is this too tall an order to generate this type of power from these two panels?

I would love to get this going and generate some power from the light of God rather than stuffing further the pockets of the power companies.

Any help really greatly appreciated and if any further info is needed please just let me know.

Thank You very much in advance for your time.

[Naptown]

Dear All and greetings from London, UK

I am a newbie and hoping to get some much needed help from the experienced and engineer minded members. ANY help would be greatly appreciated.

I am in the UK, London, so sun is not a generous commodity here and also relative to measurements/currencies it may be different to any advice/specs offered from the US but i'll do my best to understand, please imagine your explaining solar power/energy/ratings/etc to a 10 year old

I have been interested in solar/alternative power for sometime, I am not in the position to have my whole house switched but as a hobbyist I would love to build a successful small off grid system.

I would like to power 2 units, each unit is 360-400w draw and they will run 24hrs, 7 days a week.

I have an unhindered fully South Facing roof and would ultimately put the panels on this part of the roof.

I already have 2 Sharp solar panels, please see the specs of these here: http://www.sharp.eu/cps/rde/xbcr/doc...48_1109_eu.pdf

I have a 30Ah charge controller, a 1000w/2000w peak power pure sine DC12V- AC240V inverter.

What batteries would I need?

Is this too tall an order to generate this type of power from these two panels?

I would love to get this going and generate some power from the light of God rather than stuffing further the pockets of the power companies.

Any help really greatly appreciated and if any further info is needed please just let me know.

Thank You very much in advance for your time.

No way that is going to happen You have described a load of over 9KWH a day
That will take a 950AH 48 volt battery a minimum of 5 KW of panels multiple charge controllers
This is not a hobby system and what you have is a very small downpayment on what it will take

Sorry double the above there are two of them.

[Solarminer]

Thank You.

No way that is going to happen You have described a load of over 9KWH a day
That will take a 950AH 48 volt battery a minimum of 5 KW of panels multiple charge controllers
This is not a hobby system and what you have is a very small downpayment on what it will take

Sorry double the above there are two of them.

Hi Naptown.

Many thanks for your quick reply.

As I suspected even with my limited knowledge I am way off the mark. With the two panels that I have and with the right components what could I generate theoretically from these panels. I have looked up many formulas and it is all a bit confusing for me, but I'm learning a long the way.

Thank You.

[Naptown]

well 350 watts of panels x .49 sun hours in december means they would produce about 170 watt hours a day.
but you will at best get only 66% into your batteries to use so figure you could use 112 watt hours a day or a 10 watt light bulb for 11 hours.

[Solarminer]

well 350 watts of panels x .49 sun hours in december means they would produce about 170 watt hours a day.
but you will at best get only 66% into your batteries to use so figure you could use 112 watt hours a day or a 10 watt light bulb for 11 hours.

Wow, I really was way off with my hope to power my units!

So if I was to try and harness the power as per your calculation, what amp charge controller would I need and what Ah battery?

Thanks again Naptown!

[Naptown]

you will need at least a 30 amp MPPT controller.
Since you are hitting the batteries hard for a short period of time I would suggest something in the range of a 100 AH AGM battery.

[Solarminer]

you will need at least a 30 amp MPPT controller.
Since you are hitting the batteries hard for a short period of time I would suggest something in the range of a 100 AH AGM battery.

Ok all understood. I have the 30amp MPPT controller. If one puts 2 x 50ah batteries in parallel is this as effective as 1 x 100ah battery or there is some power lost between the 2?

[Naptown]

It is never a good idea to parallel batteries. best to use one large enough or lower voltage batteries in series to gt the capacity and voltage you need

[Shockah]

I can't contribute more/better info than Naptown has,

but I gotta ask, Solarminer ... What appliance are you running that draws 400watts 24/7/365?!

[Solarminer]

It is never a good idea to parallel batteries. best to use one large enough or lower voltage batteries in series to gt the capacity and voltage you need

Ok all clear, I will aim for 1 x 100ah battery.

Thank you!

[Solarminer]

I can't contribute more/better info than Naptown has,

but I gotta ask, Solarminer ... What appliance are you running that draws 400watts 24/7/365?!

Hi Shockah,

Good question!

I am running 2 x cryptocoin mining machines online, these are electricity guzzlers and I had grandioso ideas of powering them from nature, but as you will have read from Naptown's excellent (and pull me back to reality) advice, I would clearly need a mini power station to keep these things going 24/7

Still I am determined to harness a bit of natures energy and I will continue and charge my ipad with it!

[Sunking]

Still I am determined to harness a bit of natures energy and I will continue and charge my ipad with it!

Kind of pointless. Anything you take off grid is going to cost you some 5 to 10 times more than you can buy power from the electric company.

[Solarminer]

Kind of pointless. Anything you take off grid is going to cost you some 5 to 10 times more than you can buy power from the electric company.

Well indeed, but if we lived by that equation we would probably do very little. I have always been aware that the investment to set up solar can take years to produce a yield in electricity/cost. About 6 years ago our [green obsessed] government offered partial grants for the installation of solar energy systems to reduce 'carbon foot prints', they stopped it 2 years later! in that period I enquired about it for my home but was told that because I have a 4 floor house I could not have it fitted because they will only fit on 2 floor houses , worker insurance related I guess.

.....with the current climate over here and a lot of talk (nay unproductive bickering) about future energy supplies, wind, hydro, fracking, coupled with the extortionate price of energy because we import it all now......from Russia which is even more fragile right now, it doesn't seem such a bad idea regardless of my optimistic intentions to learn a little and build a little and I assume that once an off grid system is set up it can be expanded and power increased.

There is some satisfaction in knowing that despite investment you did it for yourself and are not just plugging into the wall to pay shareholder dividends and bonuses.

What do you pay a power company in the US per Kw?

[inetdog]

Well indeed, but if we lived by that equation we would probably do very little. I have always been aware that the investment to set up solar can take years to produce a yield in electricity/cost. About 6 years ago our [green obsessed] government offered partial grants for the installation of solar energy systems to reduce 'carbon foot prints', they stopped it 2 years later! in that period I enquired about it for my home but was told that because I have a 4 floor house I could not have it fitted because they will only fit on 2 floor houses , worker insurance related I guess.

.....with the current climate over here and a lot of talk (nay unproductive bickering) about future energy supplies, wind, hydro, fracking, coupled with the extortionate price of energy because we import it all now......from Russia which is even more fragile right now, it doesn't seem such a bad idea regardless of my optimistic intentions to learn a little and build a little and I assume that once an off grid system is set up it can be expanded and power increased.

There is some satisfaction in knowing that despite investment you did it for yourself and are not just plugging into the wall to pay shareholder dividends and bonuses.

What do you pay a power company in the US per Kw?

It is a big and diverse country, so rates vary.

The lowest you are likely to see, in a state like Texas or Florida, will be ~$.06/kWh.
In a state like Hawaii where fuel has to be imported by sea, rates could go above $.50/kWh.
In some areas you pay a lower rate the more you use. In others, like California, you pay a higher penalty rate if you go above the "normal" baseline usage. That could take you from a minimum of $.12 to a high (over baseline and during peak hours) of almost $.30.

Even though there are several major national power grids, with interconnections between them, the price of generated or imported power is very much a local thing.

[Sunking]

What do you pay a power company in the US per Kw?

I pay 8-cents for the first 1500 Kwh and drops to about 7-cents after that.