- Craig Nicholls
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In short in the solar game, you get what you pay for.
Our systems are designed for cameras that are always on and streaming or recording. Unlike many of the versions out there that CAN NOT record 24/7, they are off and only wake up and record when movement is detected. Also you are typically locked into the suppliers app only and you cannot integrate it with a NVR or other systems, look for ONVIF compliance if in doubt. It’s important to consider all the factors so that you don’t land up with a system that does not meet your requirements.
Here are some important concepts you need to understand first.
Solar Panel Wattage: The rated wattage of the solar panel.
Solar Panel max charge rating: The rated maximum charge (amperage) rating of the solar panel.
Dark runtime: How long the battery will power your equipment with no solar charge.
Recharge time: How long, under ideal solar radiation conditions, it will take to recharge your battery i.e. you have solar radiation in excess of 450w/m² for 6 hours. Typically in ZA this is between 09h00 and 15h00
Equipment max power consumption: The total amperage that your camera and communication equipment draw. Remember that at night its much higher than during day, that’s because at night the cameras infra-red lights come on to provide night vision.
Total battery amp size: The total power rating of your battery system (Ah).
We offer a few variations depending on your budget and requirements.
A 50W panel with either 20Ah or 25Ah.
A 80W panel with either 25Ah or 40Ah.
A 100W panel with 70Ah.
Our entry level solar kits are designed to operate our camera and communication equipment continuously through the night with a margin of error. By that I mean we match or “balance” the desired dark runtime with the a battery pack and the solar panel so that the system can recharge in under 4 to 6 hours of sunlight the next day.
Keep in mind that in South Africa we get max UV charge rate from 9am to 3pm on a clear sunny day, that’s 6 hours out of 24. That means the equipment is using battery power for 18 hours! We must therefore match the max power consumption of the connected equipment to the solar panel’s wattage and max charge rate, to ensure an effective recharge time. So we need to be able to recharge the batteries in 4 to 6 hours to be able to get through the next night again with a margin error.
Our entry system looks like this:
· 50W panel
· 20Ah hour battery packs
· dark runtime of 24 hours.
So from a fully charged system it will start operating on the battery from around 4pm, even though the sun is shining it’s not giving us enough UV charge to power the camera and connected equipment so the battery supplements the missing power requirement, after sunset we are now fully on the battery’s. The next day is a rainy overcast day with no UV radiation to charge our battery, the system will power off some time around 6pm, because we had a dark runtime of 24hours.
Lets assume it was not raining but only overcast, because we recharge on UV radiation, not direct sunlight we may extend that run time because we may be getting enough charge to power the cameras (so not using the battery’s) but no enough to recharge the batteries as well, In this instance the system will probably power off around 12pm, midnight.
Assuming the next is sunny, as soon as the charge rate gets to our required power needs the system will reboot, typically some time between 8.30am and 9am as it first needs to bring your depleted battery’s up to operating level. If you have a clear sunny day then the system will be fully recharged and operate through the night, if not it will turn off some time during the night, depending on how much charge you manged to get. But the system will always reboot and start operating when conditions are good enough.
If you want a system that has a uptime of 95% or more then you need to speck a system that has a dark runtime of 3 days, ie 72 hours and a recharge time of 4 hours. Why do I say that?
It’s not often that we have three solid days of rain and no sun, we will often have two days of no sun. We also often have two days of rain, the next day we get four hours of sun and then another two rainy days which will be fine as remember we only need 4 hours of good charge time to recharge our battery and our system is designed to run for 3 days just off the battery’s.
The biggest mistake people make is to say well I will just put a bigger battery pack on, I will put a 48amp hour battery on the system and that will give me three days. NO, it wont because your solar panel and charge controller will not be able to recharge that battery in 6 hours. Yes it might help but you wont get the 95% uptime you thought you will get.
So the impact on cost to achieve this 95% uptime is significant. Let’s look at our initial entry level system designed to operate overnight. The current system looks like this:
· 50W solar panel
· 20Amp hour battery pack
· dark runtime of 24 hours.
We want a dark runtime of 72 hours. That means we need almost three time the resources, three times the cost.
So our new system looks like this:
· 100W solar panel
· 70Ah hour battery pack
· dark runtime of 72 hours.
Why don’t we just over spec the solar panels to get a better recharge rate? There are a few reasons.
We at Foscam want a pole mount solution, not a ground-based solution as theft and vandalism is a big issue. So, size and weight matter. The bigger the batteries and solar panel the bigger size pole you need. Not so much because of the weight but because of the wind load factor. The solar panel acts like a sail in the wind. We want to minimize the chance of damage from say a storm by using a smaller system than a larger system. The force generated by the wind can rip a system off a pole if care is not taken.
You should also take note of where your located, the requirements for a system in the Nother Cape will be very different from a site in the Natal midlands, purely because the Nother cape will get more UV radiation.
Our entry level system should give you a 90% up time when averaged out over a year, if you need more then look at one of our bigger systems.
You can view our Solar products here
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