Battery Systems For PV Solar Panels

the_analyser

Hi,

Trying to get my folks to install a PV Solar Panel system in their gaff, what with peak oil and systemic collapse and all the rest. Would be very interested in hearing peoples thoughts on:

a) the size of panels needed (they used 3000Kwhs last year)

b) the battery storage systems - price, durability, ease of use etc.

c) how they would intergrate with a solar thermal aswell - would the battery system have enough power to work it if the grid isn't around?

Thanks a million,

T

dardhal

the_analyser wrote: »

Hi,

Trying to get my folks to install a PV Solar Panel system in their gaff, what with peak oil and systemic collapse and all the rest. Would be very interested in hearing peoples thoughts on:

a) the size of panels needed (they used 3000Kwhs last year)

b) the battery storage systems - price, durability, ease of use etc.

c) how they would intergrate with a solar thermal aswell - would the battery system have enough power to work it if the grid isn't around?

Thanks a million,

T

A million is about the money it is going to cost you, sorry, but the intent is to save money (even longer term), you are throwing tons of them down the drain.

In Ireland there is a severe problem with weather regarding PV: winter days are so short and cloudy days are SO many that you can't expect PV plus battery storage to be at all useful for most part of the winter, spring and fall. Only during summer you could be grid free coupling an oversizes PV array with an oversized battery rack.

For the specifics of Irish weather, to be autonomous throughout the year don't expect to spend less than 20.000€ in products, plus cost of manpower. And you will need, no matter what, a backup generator, for example, a diesel generator, for those a week in a row periods with no sunshine at all.

So you are going to spend more than 20.000€ in a very low dependable system, and lots of money, grief and unconvenience in a diesel generator for most of the winter and part of spring and fall. Very very bad business.

the_analyser

the aim is more risk management than cash saving - ie. having some power capabilities in the event of grid failure. not looking for full off-the grid living, just the ability to have some power generating capabilities. not thinking of a diesel generator either - if there are oil shortages, probably wouldn't be of much use.

so, thanks for the advice, but would be still interested in hearing your ideas for the pv and battery systems recommended for a minimal installation

dardhal

the_analyser wrote: »

the aim is more risk management than cash saving - ie. having some power capabilities in the event of grid failure. not looking for full off-the grid living, just the ability to have some power generating capabilities. not thinking of a diesel generator either - if there are oil shortages, probably wouldn't be of much use.

so, thanks for the advice, but would be still interested in hearing your ideas for the pv and battery systems recommended for a minimal installation

To start sizing an off-grid PV system you have to accurately define your daily energy consumption (in watts hour, for example, a 50 W light bulb running for four hours is 200 Wh) and for how long do you expect the batteries to last when no or minimal energy can be generated from the panels. The daily energy usage will determine the minimum PV array you have to install, and the number of days to be autonomous without grid and/or PV energy supply will determine the capacity if the batteries.

A minimal off-grid PV system consists of the same devices a larger one has: some PV panel connected to a charge controller, which charges batteries with the energy coming from the PV field, and tries to keep them in good condition. The batteries are then connected to an inverter, than converts the DC current batteries provide into AC current at a frequency and voltage your home appliances, lights, etc. can use. There are some combined charge controllers - inverters on the market. And adding to all the above, some amount of very big diameter (and so, expensive) copper connection cables, as DC currents are a whole different game than AC, and there is the need for thicker cables and specific circuit breakers and such.

PV can be bought now at about 2 €/Wp (peak watt), so a 500 Wp array would be 1000 €. A charge controller can be 200 € (500 Wp) and a 500 W AC inverter around 400 €. Batteries as quite expensive, and ones that can hold about 12.000 Wh (gross simplification, I know) are around 2000 €. It may seem I have more than over estimated the battery capacity, but take into account that batteries should not be depleted but seldomly more than 30% or so, or else they will degrade fast and loose total capacity.

So, excluding lots of necessary accessories and labour costs, you have to invest starting at around 3000-4000 €, and the system may not fit your needs at all regarding power output or autonomy.

One thing is to prepare for war conditions, mad-max post global crisis or end of civilization as we now it, and one very different thing is just the desire to be on the safe side when (if) power outages happen, for whatever reason: it is orders of magnitude easier and cheaper a diesel generator and some jerrycans full of diesel than a PV, and diesel will last you some weeks, while with PV plus batteries you could be very well in the dark due to weather conditions.

Hope it helps.

eth0

Get one solar panel and controller off ebay. Maybe 100w if you dont find that size panel too cumbersome

Then all you need is a deep cycle lead acid battery or a few used car batteries and an inverter. This will give you a minimalist off the grid setup and also useful if you want to go camping. In the summer you could use the power from this for various things but keep in mind modified sine wave inverters arent great for running things with AC motors in them

Buying a massive PV installation is the Hollywood greenwashing way to living off the grid. Or going off the grid by throwing endless amounts of money at the project so it will support your current modern Westernised consumption habits - completely impractical. If you seriously wanted to live off the grid you need to slowly start replacing inefficient appliances, getting replacements that run off 12v so dont require inverters, cutting electricity use and getting by with very little. Even if you never go off the grid a lot of this will pay off. Spending 20k on solar panels so you can run the electric shower will never pay off

Thunderbird2

Hi. I was looking at solar kits on ebay and was wondering if anyone could advise me on what size panel would be worth getting
It would be used to send 500( more if advised) watts around the house while we still had the main grid coming in.. Its just to knock a few quid off the bill

maddragon

I am a huge fan of PV and have installed several systems here and abroad but if you want to go off grid it is not recommended in a country where there is a reliable grid like in Ireland. The batteries will cost the same again as the panels. I installed a 3.37 kw peak grid tied system in Galway recently for about 13K. This will produce around 3400 kwh per year but as dardhal pointed out, it will produce very little in Winter. At current prices the payback is around 20 years but the panels have a 25 year warranty and should last indefinitely. The inverter (1.7 k) will last around 10 years. Of course Electricity prices will increase cutting down the payback time. Also PV has reduced dramatically in price in recent years but further such dramatic drops are unlikely. Pm me if you want a quote. Get a small geny if you want to prepare for the few power cuts we have here.

To dardhal; if you can get European manufactured PV for 2 eur per watt please tell me where. I buy my stuff from Germany and including VAT etc it is about 2.6eur.

the_analyser

So, the inverter costs €1.7k? If the inverter only lasts 10 years, is this the most likely point of fail in a system? Also, as a total novice speaking here, are there appliances on the market that actually use DC instead of AC?

I have read about different battery packs, some of which last longer than others, but require distilled water for maintenance. Are these recommended, and if so, what kind of damage are we looking at for a distillation unit, and could it run itself off the panels?

My folks currently use only about 3000kwh per year as is, so would probably only be looking for an smaller install than the Galway one. What kind of electric output would the panels produce during the winter, if anything at all?

eth0

the_analyser wrote: »

So, the inverter costs €1.7k? If the inverter only lasts 10 years, is this the most likely point of fail in a system? Also, as a total novice speaking here, are there appliances on the market that actually use DC instead of AC?

I have read about different battery packs, some of which last longer than others, but require distilled water for maintenance. Are these recommended, and if so, what kind of damage are we looking at for a distillation unit, and could it run itself off the panels?

My folks currently use only about 3000kwh per year as is, so would probably only be looking for an smaller install than the Galway one. What kind of electric output would the panels produce during the winter, if anything at all?

3000kwh is a lot for an off grid set up. 12v and 24v DC appliances are plentiful if you look around for them on the interweb. if you don't need to run anything heavy you can get away with several small inverters. a good quality 2kw+ pure sine wave inverter can cost that much but maybe you don't need one at all

the best kind of batteries for off-grid are the 'Nickel Iron' type. they dont degrade over time like other batteries

quentingargan

I'm not sure I would have the same pro-European manufacture bias. There is a prejudice to Chinese PVs out there, but I don't see any basis for it. I visited some PV plants in Changzhou, and the standards were very high. You just can't make PVs in a shed - you need a clean room and FAB plant, the whole thing out there is thoroughly inspected by TUV and others to the same standards. You can buy Chinese PVs with TUV certification, with production warranties for 25 years insured by Chubb for about €1.60 per watt including VAT, and the price is still falling I think (but not by much more).

Our house has been off-grid for the last 8 years running on batteries, and unless you take very good care of your batteries, they won't last their theoretical number of cycles. I would agree that if there is a grid, it is more financial sense to hook into it.

You may have a system that produces 3400 Kw Hrs a year, and if you export that, it will all get used and/or sold. But off-grid, you will have more than you need in the summer, and a lot less than you need in the winter. Batteries cannot be used to store power from summer to winter. Unless you also have a balancing input from wind or hydro which is the other way up seasonally, you are going to run into problems.

If you really want to go off grid for other reasons, PM me and I can give you info on the batteries I have opted for - they're maintenance free and have a claimed life of 3,000 cycles if used sensibly. I've also been designing controllers to try to optimise battery life through careful management and so far the systems are working well - much better than the controller I originally had purchased.

maddragon

the_analyser wrote: »

So, the inverter costs €1.7k? If the inverter only lasts 10 years, is this the most likely point of fail in a system? Also, as a total novice speaking here, are there appliances on the market that actually use DC instead of AC?

I have read about different battery packs, some of which last longer than others, but require distilled water for maintenance. Are these recommended, and if so, what kind of damage are we looking at for a distillation unit, and could it run itself off the panels?

My folks currently use only about 3000kwh per year as is, so would probably only be looking for an smaller install than the Galway one. What kind of electric output would the panels produce during the winter, if anything at all?

There are DC appliances but these are more expensive than AC equivalents but it is the best way to go if you are going for mad max scenario. If you are a novice as you say I would not recommend anything other than maintenance free batteries.

Thanks for the info on the Chinese PV Quentin.

maddragon

OP, log on to homepower.com and buy 3 years subscription for about €25. It'll answer all your questions and show you more ideas than we could possibly cover here.

quentingargan

maddragon wrote: »

There are DC appliances but these are more expensive than AC equivalents but it is the best way to go if you are going for mad max scenario.

Many DC appliances are designed for cars where there is an alternator spinning all the time. For example, when I lived on a boat, everyone used car stereos, but they guzzled electricity, and a conventional ghetto plaster worked much more efficiently.

Apart from fridges and freezers and most lights, most household appliances actaully run on DC power ultimately. You can use very cheap DC DC converters to produce the required voltage. For example, this one, costs about €7 and comes in a range of voltages. There are cheaper ones (e.g. the LM78 series of voltage regulators, but this one is more efficient.

So if you have a 24V battery pack, you can usually find a voltage regulator to step the voltage down to whatever the requirement of an appliance is.

eth0

Chinese outsourcing is bleeding the european economy dry though and nobody dares to speak about it really for fear of offending the chinese. We are already too dependent on them. They're a ruthless bunnch of communists hell bent on taking over the world and the world would be a very nasty place to live in if the chinese controlled it all

Macha

[mod]OK, that's enough racism.Cut it out please.[/mod]

dardhal

maddragon wrote: »

o dardhal; if you can get European manufactured PV for 2 eur per watt please tell me where. I buy my stuff from Germany and including VAT etc it is about 2.6eur.

It was precisely on this forum where I was contacted by a forum member about availability of such low priced, quality modules in Ireland (I'm about to send you his nickname for you to check).

The other source of pricing information is several web sites in Spain, where I come from, and prices for end users are quite affordable, and there are even "group buys" that can drive prices even lower (although I don't know if they include VAT, at 18% in Spain):
Group buys of diverse PV and RE hardware:
http://www.suelosolar.com/presupuestos/informe_ofertas.asp

Capt'n Midnight

Check hours of day light on met.ie for your location
http://www.met.ie/climate/sunshine.asp

December is the dullest month with an average daily sunshine ranging from about 1 hour in the north
...
A more recent summer, 1980, was the dullest. The difference was considerable, with the summer of 1887 being twice as sunny as that of 1980.

So for Donegal you could need 18 times as many solar panels in Winter to match the output of ONE in Summer. And that's on a good day, if it's overcast / raining it could be worse.

This means you'd need batteries for 23 hours a day , and possibly a few days during a storm.


For emergency use buy a generator.

eth0

On the Shetland Islands you need an infinite amount of solar panels in the winter to generate any power at all. but for year round off the grid use you should use both and preferably have some micro hydro set up as well

Rogue_art

I strongly agree! Off grid PV will only make sense if Grid Connected PV is not possible / practical. A retired neighbor of mine installed a 1.9kWp Grid connected PV system on his cottage a couple of years ago. Between the Feed-in tariff it earns and the Electricity allowance he receives as a pensioner, he says his ESB account is generally in Credit and he rarely has to pay for electricity.

To maddragon;, I know of someone who recently got about 1.7kWp of European manufactured PV for well under the prices you are paying, and they are an irish supplier. try them yourself <modsnip></modsnip>