M

Maartin1965

Hi All.

I am new to this forum. I am a sparky whom has been largely out of the trade for 20 years, with the exception of the odd little job for friends, but training wise, doing my 17th edition along with my part P.

I am planning an off grid Solar PV/battery install on a 4 bed house I am currently building in west Africa (Gambia). Solar PV is relativity unused out there, which is nuts given the average of 12 hours of full sun @30-45 degrees for 340+ days per year. Also the standard of their electrical installations is literally shocking! So I will be doing the install myself, using materials sourced in the UK and shipped out. So, any advice you guys can give me on reasonably price good equipment (new or used), would be greatly appreciated!

So my queries are :-
Batteries, should I go down the lead acid, gel or lithium route? Whilst I understand the need of deep cycle, I can not find any real obvious advantage for gel over lead acid, in fact my research with a couple of battery suppliers leans me towards lead acid, with the maintenance/topping up option (correct me if I am wrong)! Or is it worth investing in the lithium route bearing in mind this property will only be occupied for maybe 4 months of the year?

Also, the size (capacity) of the array and battery bank is a theoretical stumbling block. As I have never designed a system before, let alone contemplated fitting one! So I am guessing it starts with demand, then battery capacity to supply the demand and so on, working your way up the list!

I calculate that my maximum short peak demand will be about 10kw (for 5-10 minutes), with a normal maximum interim load of 6kw (for max 1 hour). The normal running load of the installation will be approximately 1.5kw - 2kw (running essentials, fridges, lighting etc) while the property is habited. In the off season the load will be a mere trickle used by the watchman for occasional night lights around the compound and lights within his 1 bed apartment. All loads will be 240v to reduce cable sizes and keep voltage drops to a minimum, so everything will run through the inverter.

I am leaning towards 12 x Polycrystalline panels with an output of 220w each (giving a max of 2640w), Would these be sufficient? Also what size batteries should I be looking at? in terms of amperes per hour rating to cope with my load usage.

There will be a generator back up provided by a 5kw constant output dual fuel electric start unit, this will be wire in as an auto start up unit, linked to battery levels.

Many thanks in advance and my apologies for bombarding you with so many questions.

Martin.
 
Seeing as this is a specialist area within our industry, you would be better off paying a design consultant. They will do the calcs and specifiy what equipment is needed. I think the hot arid environment will throw up some of its own problems. Shouldn't cost a fortune either...
 
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First thing I'd look at is your demand, as those figures are incredibly high for a house, and you'll be spending an absolute fortune on solar PV and batteries / inverters to supply that lot, so reduce your demand to a more sensible level first.
Most low energy UK houses have a base load more like 100-150W, which is much more doable.

As for sizing - size for the worst periods of sunlight in the year.
 
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Maartin1965,
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Gavin A,
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