diy solar

diy solar

How do i calculate solar

P

Paulus

New Member
Joined
Jan 26, 2020
Messages
6
Hi guys

My name is Paulus i'm from South-America Paramaribo-Suriname
i have a few question how do you calculate 1. solar panels 2.solar charger mppt or pwm 3. Batteries 4.inverter for a avarage house of 800w a day peak sun hour 4/5hours
or is there a formula online where i can find it and calculate it my self.


Thank you
 
Welcome to the forums.

You need to understand your load for the house in terms of watt hours. For example if you use 100 watts for lighting, 5 hours per day, that is 500 watt hours. You also need to know your peak watts. While you have the 100 watts of lighting on, if you run a 1000 watt microwave for 3 minutes, that is 1100 watts peak, if nothing else is ever on at the same time. So you need to know both peak and daily demand.

Then consider what type of battery you use. Lead acid is less cost on the initial cost but don't deliver full rating in amp hours and wear out sooner (fewer cycles) than lithium. If you know your load numbers and battery type that you plan to use, then you can start looking at size options. Also, how many days must you operate with very little sun? Do you see solid clouds for several days in a row? If yes and if you having power is critical, then your battery will need to be larger, to carry you past those cloudy days.
 
DThames said:
Welcome to the forums.

You need to understand your load for the house in terms of watt hours. For example if you use 100 watts for lighting, 5 hours per day, that is 500 watt hours. You also need to know your peak watts. While you have the 100 watts of lighting on, if you run a 1000 watt microwave for 3 minutes, that is 1100 watts peak, if nothing else is ever on at the same time. So you need to know both peak and daily demand.

Then consider what type of battery you use. Lead acid is less cost on the initial cost but don't deliver full rating in amp hours and wear out sooner (fewer cycles) than lithium. If you know your load numbers and battery type that you plan to use, then you can start looking at size options. Also, how many days must you operate with very little sun? Do you see solid clouds for several days in a row? If yes and if you having power is critical, then your battery will need to be larger, to carry you past those cloudy days.
Click to expand...


hi i can only find maintenance free sealed rechargeable battery 12v200ah cuz lithium batteries need to be shipped if i need themand cost $$$$
total watt-hour is 2600WH with 3 days backup = 7800WH.
i read somewhere online that the maintenance free sealed rechargeable battery DOD 50% i do not know if it is true.
so from here on out i need to calculate the solar panel highest i have seen is 250Watt panel , solar charger i only see PWM MPPT also difficult to find Batteries and inverter.

Thank you for your fast reply
 
Santa said:
And the first one: https://diysolarforum.com/threads/beginner-video-playlist.232/ Have not had coffee yet!
Click to expand...
lol i will check them soon but at the mean time can you help me out with this
i can only find maintenance free sealed rechargeable battery 12v200ah cuz lithium batteries need to be shipped if i need themand cost $$$$
total watt-hour is 2600WH with 3 days backup = 7800WH.
i read somewhere online that the maintenance free sealed rechargeable battery DOD 50% i do not know if it is true.
so from here on out i need to calculate the solar panel highest i have seen is 250Watt panel , solar charger i only see PWM MPPT also difficult to find Batteries and inverter.
 
Paulus said:
lol i will check them soon but at the mean time can you help me out with this
i can only find maintenance free sealed rechargeable battery 12v200ah cuz lithium batteries need to be shipped if i need themand cost $$$$
total watt-hour is 2600WH with 3 days backup = 7800WH.
i read somewhere online that the maintenance free sealed rechargeable battery DOD 50% i do not know if it is true.
so from here on out i need to calculate the solar panel highest i have seen is 250Watt panel , solar charger i only see PWM MPPT also difficult to find Batteries and inverter.
Click to expand...
Do you mean sealed lead acid battery? If so, yes, the depth of discharge is 50%. They're cheaper in the beginning, but you can discharge the lithium iron phosphate (LiFePo) batteries almost down to 0% and you get A LOT more service time on the lithium batteries (meaning more years.) Also, the weight of lead acid is a lot more if that concerns you. You might consider that, but you buy what you can afford, etc.

Have you looked at Will Prowse's blueprints? here: https://www.mobile-solarpower.com/ It sounds like you need a lot of power. Cheers!
 
The spread sheet is designed to start with an energy audit and then size the system. There is nothing magic in any of the calculations and it allows you to play with assumptions to see what changing things up does to/for you.

To get the best sizing, used measured values of wattage for the load calculations. If you use the values shown on the back of the device, it will almost always be higher than actual. The higher-than-actual number then gets fed into the system sizing and the difference can get amplified.

The energy audit table also helps you understand what your energy hogs are. This helps you know where to work on usage reduction.
 
One more thing. For things like refrigerators that cycle on and off, it is sometimes hard to come up with an hours-of-use for them. If you can stick a Kill-a-Watt on it, you can get a good measure of the Watt-hr usage.
 
Santa said:
Do you mean sealed lead acid battery? If so, yes, the depth of discharge is 50%. They're cheaper in the beginning, but you can discharge the lithium iron phosphate (LiFePo) batteries almost down to 0% and you get A LOT more service time on the lithium batteries (meaning more years.) Also, the weight of lead acid is a lot more if that concerns you. You might consider that, but you buy what you can afford, etc.

Have you looked at Will Prowse's blueprints? here: https://www.mobile-solarpower.com/ It sounds like you need a lot of power. Cheers!
Click to expand...

Santa said:
Do you mean sealed lead acid battery? If so, yes, the depth of discharge is 50%. They're cheaper in the beginning, but you can discharge the lithium iron phosphate (LiFePo) batteries almost down to 0% and you get A LOT more service time on the lithium batteries (meaning more years.) Also, the weight of lead acid is a lot more if that concerns you. You might consider that, but you buy what you can afford, etc.

Have you looked at Will Prowse's blueprints? here: https://www.mobile-solarpower.com/ It sounds like you need a lot of power. Cheers!
Click to expand...
yes sealed lead acid battery
 
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