Wanakijiji tusaidiane hapa…

Lets say I want to power a 32 inch screen Tv of about 150 watts, 2 bulbs of 75 watts each and a 4000mah(4Ah) phone…this adds up to about 300 watts.

You will need a battery whether MF or Vented (ile ya kuongezea maji) of atleast 100Ah of 12V
Watts =I(current) volts…10012=1200 watts

Consumption of the battery will depend on the gadgets to be used


  1. Solar panel of about 150 watts should do (about 20k).This is good as one can use high capacity battery.

  2. Charger controller (placed between solar panel and battery when setting up)…helps prevent the battery from draining when fully charged. Allows only one way movement of current from solar panel to the battery. This ensures durability of the battery (charge(s) and discharge(s) reduces the lifespan of a battery.

3.090 or 045 battery recommended for light consumption. Heavy consumption including heaters and ironing requires NS90 or N90 battery whether MF or vented. The 150 watts solar panel should be able to charge this comfortably.

  1. Inverter which should be a third of capacity or consumption output (after calculating the watts used by all the gadgets in a household)

  2. Wiring where you improvise a consumer unit or meter. Here wiring is done differently not like KPLC.

Personally I prefer to use MF automotive battery even in solar.
@uncle nyam, @Reri @madova…kujeni hapa



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A 75w bulb??? fluorescent is 15w… do the math…

Yes there are 5 Watt led bulbs very bright and recommended for solar. Also i wont think it’s viable to heat with solar. From experience, it drains the batteries real quick hence a short lifespan. What brand of batteries do you use?

When using solar, you should use LED panels for lighting. Not single LED bulbs, but panels. kes2500 kupanda.
100AH battery for heavy use will need 500 watts solar panel, unless you live in sahara and the panel can tilt itself.
Again 100AH at 12 volts means that the battery can provide 100 amps for 1hour at 12V, or can provide 1 amp for 100 hours at 12V, or can provide 12W for 100 hours, or can provide 1200W for 1 hour. You can calculate the total energy in the new fully charged battery by doing 1200W*3600 = 4320KJ.
You can now make estimates with that figure if you can calculate the total energy required by appliances and account for inevitable losses. I bet you will need two batteries for comfortable use. If you have heaters you will need heavy duty batteries(like ones used in base station back ups). Reliable solar power set up is expensive. If you can get german or japanese panels the better.

LED equivalent ni 12 watts

the automotive battery cannot be drained to more than 20% its value if you do it will not last but a solar battery is designed to be drained to more than 80% its value so called deep cycle


I was away in some village where internet was crap.
First of all is to calculate the power in watts multiplied by number of hours the equipment’s are meant to run.
Divide your total with system voltage i.e 12/24/48 V in this case yours is 12V, and inverter efficiency 0.90(in case you have ac powered stuff)
This will give you the battery size.
You need to factor in the days when weather is bad(Autonomy days),so that you will still have your system working.
Secondly automotive batteries are not good for a solar system since they discharge up to 50% while deep cycle batteries discharge to 80%.
For the batteries you can go for wet ,maintenance free or tubular ones which are 2V with a higher AH then connect them in series.
The size of the solar is determined by sunshine hours,this is the number of hour sun hours in you location.
The average is 6-8 hrs depending on the region
Solar size is given by dividing AVERAGE LOAD divided by battery efficiency 0.8/0.5 divided by sun hours(6-8).


My missus was transferred to a remote location which is not yet on the grid am keenly following since i need to hook her up she just requires a set up to run a 32inch tv dvd and go tv decoder charge phone and laptop occasional ironing and lighting up two rooms

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With a battery of 100AH(mf) , 1 solar panel of 230watts,and an inverter charger of 500w you will be sorted…

I disagree.A 500w inverter consumes around 40AH hour meaning with a 100AH battery you only have 1 hour to run before low battery show on the inverter.
Another thing which kind of inverter square wave,semi square or pure sine wave.
The best inverters are XANTREX,PHONEX/VICTRON.
A 230W delivers a current of 13 AMPS which translates to a bigger battery of 150-180AH.

wow… av learnt something new today … re doing my calculations again.

The thing is that you should avoid using inverters. they consume more than the applicances. modern TVs have a 12V jack and there are 18/19/20V DC adapters. There DC adapters for laptops too. Avoid inverters. If you must have them then be prepared to install huge panels and equally massive batteries.
Most proposals for solar power I am seeing here cost about 100k, but if you want trouble free solar power that outputs 240V~ mains you gotta spend much more.


Another way if someone wants an interrupted power supply in case power chucks(if already connected to the grid) is to have an inverter/charger and a battery back up.
This inverter has a change over that operates on a split of a second in case of power loss.

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That puts the solar panel out of the math and is much easier.

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@kev , I see @madova has ably jumped in with great contributions.
As you saw in my post on other threads, I am currently more interested on solar energy storage technology, used in off the grid “stand alone” power plants for commercial use.
However, I am following keenly the discussion on use of solar in residential homes.

So mnasema it’s cheaper kutumia solar energy than knower. .how about during bad weathers and I still need power

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Kindly explain the commercial bit.
What are the power requirements?

In regards to bad weather a factor is used to calculate the size of the system to cater for this.
Solar systems are expensive to purchase but beneficial in the long run.

Nobody said its cheaper.

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first things first ironing is out in the system that you planing to get. but you can

Example: A house has the following electrical appliance usage:

[li]One 18 Watt fluorescent lamp with electronic ballast used 4 hours per day.[/li][li]One 60 Watt fan used for 2 hours per day.[/li][li]One 75 Watt refrigerator that runs 24 hours per day with compressor run 12 hours and off 12 hours.[/li][/ul]
The system will be powered by 12 Vdc, 110 Wp PV module.

1. Determine power consumption demands

Total appliance use = (18 W x 4 hours) + (60 W x 2 hours) + (75 W x 24 x 0.5 hours)

= 1,092 Wh/day

Total PV panels energy needed = 1,092 x 1.3

= 1,419.6 Wh/day.

2. Size the PV panel

2.1 Total Wp of PV panel capacity
needed = 1,419.6 / 3.4

= 413.9 Wp

2.2 Number of PV panels needed = 413.9 / 110

= 3.76 modules

      Actual requirement = 4 modules

So this system should be powered by at least 4 modules of 110 Wp PV module.

3. Inverter sizing
Total Watt of all appliances = 18 + 60 + 75 = 153 W
For safety, the inverter should be considered 25-30% bigger size.
The inverter size should be about 190 W or greater.

4. Battery sizing
Total appliances use = (18 W x 4 hours) + (60 W x 2 hours) + (75 W x 12 hours)
Nominal battery voltage = 12 V
Days of autonomy = 3 days

Battery capacity = [U][(18 W x 4 hours) + (60 W x 2 hours) + (75 W x 12 hours)][/U] x 3 
                                            (0.85 x 0.6 x 12)
Total Ampere-hours required 535.29 Ah

So the battery should be rated 12 V 600 Ah for 3 day autonomy.

5. Solar charge controller sizing
PV module specification
Pm = 110 Wp
Vm = 16.7 Vdc
Im = 6.6 A
Voc = 20.7 A
Isc = 7.5 A
Solar charge controller rating = (4 strings x 7.5 A) x 1.3 = 39 A
So the solar charge controller should be rated 40 A at 12 V or greater.