What Size Panel & Charge Controller?
Determine your Solar Needs
Once you have determined your battery requirements, you will want to know how much solar power you will need to recharge your batteries, preferably in one day!
As a general rule we would want a battery charging current of at least 10% of the total Amp Hour rating of our battery bank. e.g. A 100 Amp Hour battery will need at least a 10 Amp charge rate, but higher is better.
This is not an exact science due to the many factors involved in our weather patterns, but lets just say that we can expect 4 hours of direct sunlight each day.
Lets take our example 2400Wh batteries scenario from the sizing a battery page and then divide that number by the hours of expected sunlight.
2400 divided by 4 gives us 600. So we will need a solar array that can supply us with 600 watts of power. e.g. 3 x 200 watt panels, 2 x 300W etc
We now know our battery size, our solar panel needs and we now need to figure out what size of solar charge controller we will need to recharge the batteries.
Always aim to buy an MPPT charge controller, these will get more power from your solar panels than cheaper PWM versions.
This is simple!
We take our Solar Panel wattage and divide that by the voltage of our Batteries.
So if we are using 12 volt batteries, the calculation would be 600W divided by 12V = 50A.
This is the amp rating we need for a charge controller, but its usually a good idea to go higher, so i would suggest a 60A solar charge controller.
However, if we decided to connect our 2 x 12V 100Ah batteries or 4 x 12v lead acid in series to give us 24 Volts we could buy a smaller rated charge controller e.g. 600W divided by 24V = 25A
So by making a simple series connection at the batteries to make it 24 volts, we could recharge the batteries using a 30 Amp Controller.
This offers good cost savings when it comes to wire costs too as the higher the voltage the less the cables will cost.
Best Value for money - RENOGY ROVER Series (Click this link to go to eBay listings) or use the links below to shop on Amazon.
Best Quality but Cost More - VICTRON MPPT & BLUETOOTH Amazon & eBay Links
Clicking these links will take you to eBay or Amazon.
Amazon - 100/15 Amp Victron 12/24v or buy from eBay Here
Amazon - 75/15 Amp Victron 12/24v or buy from eBay Here
Amazon - 100/20 Amp Victron 12/24v or buy from eBay Here
Amazon - 100/30 Amp Victron 12/24v or buy from eBay Here
Amazon - 100/50 Amp Victron 12/24v or buy from eBay Here
Amazon - RS450V/100A\48V Smart-Solar (Ideal for server racks batteries)
MPPT 30A Solar Charge Controller
Solar Charge Controllers
Victron Charge Controllers
Victron are the market leaders for solar charge controllers (SCC) The first number is the max solar input, the second is the maximum amps it can charge at.
Inexpensive 30A SCC PWM
This is a very inexpensive PWM solar charge controller, ideally used with lead acid batteries as it has no LifePo4 charge profile.
Renogy Charge Controllers
Renogy Charge Controllers
Best value for money is the Renogy Rover MPPT series.
Solar Charge Controllers
Victron Solar Charge Controllers
Victron make great products but are slightly more expensive than competitors. They come in MPPT and a offer a good range of amp sizing. These are Highly popular, built to great standards & if you have the money go with Victron units. I use the 110/30 Smart Version, it is simple to set up. Its a very good quality item!
EPEVER MPPT 40 Amp
This is another one of my personal favourites. It has has good sized terminals and great heat dissipation. Plug and play if you are using lead acid batteries but you will need the MT50 unit to programme other battery profiles, which isn't straight forward, be sure to read instructions!
Victron Smart MPPT is easier to set up
EPEVER Brand Solar Charge Controllers
EPEVER have been around a while and offer good products and good pricing. They come in 10A versions up to 100A and have a very good reputation.
RENOGY Branded Products
Renogy offer a Good range of solar products, solar charge controllers, solar panels and other accessories. Easy to programme & ideal to use with lithium iron Lifepo4 batteries.
Budget 30A Charge Controller
This is a budget solar charge controller rated for 30Amps. It comes in different amp ratings and has USB charge ports. This is a PWM unit and being a budget item it isn't build to high standards
GCSOAR 60A With Wifi
Excellent 60A controller with WiFi and cloud function. Easy to set up and lots of options